ࡱ> #` Pbjbj\.\. 4T>D>D\%D^D^D^8|^|`4M28b l"$l$l s,̕9s$]srrrδδtXrrrMttttdQ@Z@Z Chapter 16 Cleaning and Shaping William T. Johnson D.D.S., M.S. W. Craig Noblett D.D.S., M.S. Learning Objectives After reading this chapter, the student should be able to: 1 State reasons and describe situations for enlarging the cervical portion of the canal before performing straight-line access. 2 Define how to determine the appropriate size of the master apical file. 3 Describe objectives for both cleaning and shaping; explain how to determine when these have been achieved. 4 Diagram perfect shapes of flared (step-back) and standardized preparations; draw these both in longitudinal and cross-sectional diagrams. 5 Diagram probable actual shapes of flared (step-back) and standardized preparations in curved canals. 6 Describe techniques for shaping canals that are irregular, such as round, oval, hourglass, bowling-pin, kidney-bean, or ribbon-shaped. 7 Describe techniques, step-by-step, for standardized and flaring (step-back and/or crown-down) preparations. 8 Distinguish between apical stop, apical seat, and open apex and discuss how to manage obturation in each. 9 Describe the technique of pulp extirpation. 10 Characterize the difficulties of preparation in the presence of anatomic aberrations that make complete dbridement difficult. 11 List properties of the ideal irrigant and identify which irrigant meets most of these criteria. 12 Describe the needles and techniques that provide the maximal irrigant effect. 13 Discuss the properties and role of chelating and decalcifying agents. 14 Explain how to minimize preparation errors in small curved canals. 15 Describe techniques for negotiating severely curved, blocked, or constricted canals. 16 Describe, in general, the principles of application of ultrasonic devices for cleaning and shaping. 17 Evaluate, in general, alternative means of cleaning and shaping and list their advantages and disadvantages. 18 Discuss nickel-titanium hand and rotary instruments and how the physical properties of this metal affect cleaning and shaping. 19 Discuss the properties and role of intracanal, interappointment medicaments. 20. List the principal temporary filling materials; describe techniques for their placement and removal. 21. Describe temporization of extensively damaged teeth. 22. Outline techniques and materials used for longterm temporization. OUTLINE INTRODUCTION Principles of Cleaning Principles of Shaping CURRENT CONTROVERSIES IN CLEANING AND SHAPING Termination of Cleaning and Shaping Degree of Apical Enlargement Elimination of Etiology Apical Patency PRETREATMENT EVALAUTION PRINCIPLES OF CLEANING AND SHAPING IRRIGANTS AND LUBRICANTS Sodium Hypochlorite Chlorhexidine SMEAR LAYER DECALCIFYING AGENTS EDTA/Citric Acid MTAD TECHNIQUES OF PREPARATION Watch Winding Reaming Filing Circumferential filing Standardized preparation Step-back Technique Canal Bed Enlargement Reverse Flaring Technique Anti-Curvature Filing Balanced Force Technique Nickel Titanium Rotary Preparation Apical Clearing Recapitulation Combination Technique General Considerations A Review CRITERIA FOR EVALUATING CLEANING AND SHAPING LUBRICANTS INTRACANAL MEDICAMENTS Phenols and aldehydes Calcium hydroxide Corticosteroids Chlorhexidine Temporary restorations Objective of temporization Routine access cavities Extensive coronal breakdown INTRODUCTION Successful root canal treatment is based on: establishing an accurate diagnosis and developing an appropriate treatment plan; applying knowledge of tooth anatomy and morphology (shape); and performing the debridement, disinfection, and obturation of the entire root canal system. Initially emphasis was on obturation and sealing the radicular space. However no technique or material provides a seal that is impervious to moisture either from the apical or coronal areas. Early prognosis studies indicated failures were attributed to incomplete obturation. ADDIN EN.CITE Ingle20029774977428Ingle, J. I.Endodontics7485th Edition ed 2002Hamilton, LondonBC Decker, Inc 1 This proved fallacious as obturation only reflects the adequacy of the cleaning and shaping. Canals that are poorly obturated are often incompletely cleaned and shaped. Adequate cleaning and shaping and establishing a coronal seal are the essential elements for successful treatment with obturation being less important for short term success. ADDIN EN.CITE Sabeti20069773977317Sabeti, M. A.Nekofar, M.Motahhary, P.Ghandi, M.Simon, J. H.Department of Endodontics, University of Southern California, Los Angeles, California.Healing of apical periodontitis after endodontic treatment with and without obturation in dogsJ EndodJ Endod628-333272006Jul0099-2399 (Print)167934682 Elimination (or significant reduction) of the inflamed or necrotic pulp tissue and microorganisms are the most critical factors. The role of obturation in long term success has not been established but may be significant in preventing recontamination either from the coronal or apical areas. Sealing the canal space following cleaning and shaping will entomb any remaining organisms ADDIN EN.CITE Delivanis19839776977617Delivanis, P. D.Mattison, G. D.Mendel, R. W.The survivability of F43 strain of Streptococcus sanguis in root canals filled with gutta-percha and Procosol cementJ EndodJ Endod407-10910AnimalsBismuth/ administration & dosage/pharmacologyCatsDental Pulp Cavity/ microbiologyGutta-Percha/ administration & dosage/pharmacologyResins, Synthetic/ administration & dosage/pharmacologyRoot Canal Filling Materials/ administration & dosage/pharmacologyRoot Canal TherapyStreptococcus sanguis/drug effects/ physiologyZinc/ administration & dosageZinc Oxide/ administration & dosage/pharmacology1983Oct0099-2399 (Print)65791643and, with the coronal seal, prevent re-contamination of the canal and periradicular tissues. Principles of Cleaning Nonsurgical root canal treatment is a predictable method of retaining a tooth that otherwise would require extraction. Success of root canal treatment in a tooth with a vital pulp is higher than that of a tooth that is necrotic with periradicular pathosis. The difference is the persistent irritation of necrotic tissue remnants, and the inability to remove the microorganisms and their by-products. The most significant factors affecting this process are tooth anatomy and morphology, and the instruments and irrigants available for treatment. Instruments must contact and plane the canal walls to debride the canal (Figure 16-1, 16-2, 16-3). Morphologic factors such as lateral (Figures 16-2) and accessory canals, canal curvatures, canal wall irregularities, fins, cul-de-sacs (Figures 16-1), and ishmuses make total debridement virtually impossible. Therefore the goal of cleaning not total elimination of the irritants but it is to reduce the irritants. Currently there are no reliable methods to assess cleaning. The presence of clean dentinal shavings, the color of the irrigant, and canal enlargement three file sizes beyond the first instrument to bind have been used to assess the adequacy; however, these do not correlate well with debridement. Obtaining glassy smooth walls is a preferred indicator. ADDIN EN.CITE Walton19923502350217Walton, R. E.Department of Endodontics, University of Iowa College of Dentistry, Iowa City.Current concepts of canal preparationDental Clinics of North AmericaDental Clinics of North America309-263621992Apr15725014 The properly prepared canals should feel smooth in all dimensions when the tip of a small file is pushed against the canal walls. This indicates that files have had contact and planed all accessible canal walls thereby maximizing debridement (recognizing that total debridement usually does not occur). Principles of Shaping The purpose of shaping is to 1) facilitate cleaning and 2) provide space for placing the obturating materials. The main objective of shaping is to maintain or develop a continuously tapering funnel from the canal orifice to the apex. This decreases procedural errors when cleaning and enlarging apically. The degree of enlargement is often dictated by the method of obturation. For lateral compaction of gutta percha the canal should be enlarged sufficiently to permit placement of the spreader to within 1-2 millimeters of the corrected working length. There is a correlation between the depth of spreader penetration and the apical seal. ADDIN EN.CITE Allison1979101061010617Allison, D. A.Weber, C. R.Walton, R. E.The influence of the method of canal preparation on the quality of apical and coronal obturationJ EndodJ Endod298-304510AutoradiographyCalcium RadioisotopesComparative StudyEvaluation StudiesHumansIn VitroRoot Canal Obturation/methodsRoot Canal Therapy/ methods1979Oct0099-2399 (Print)2977505 For warm vertical compaction techniques the coronal enlargement must permit the placement of the pluggers to within 3 to 5 mm of the corrected working length. ADDIN EN.CITE Schilder19748147814717Schilder, H.Cleaning and shaping the root canalDental Clinics of North AmericaDental Clinics of North America269-961821974Apr45225706 As dentin is removed from the canal walls the root is weakened. ADDIN EN.CITE Wilcox1997101071010717Wilcox, L. R.Roskelley, C.Sutton, T.Department of Endodontics, University of Iowa, Iowa City 52242, USA.The relationship of root canal enlargement to finger-spreader induced vertical root fractureJ EndodJ Endod533-4238HumansIn VitroMaxillaRoot Canal Obturation/ adverse effects/ instrumentationRoot Canal Preparation/ adverse effects/ instrumentationTooth Fractures/diagnosis/ etiologyTooth Root/ injuriesTransillumination1997Aug0099-2399 (Print)95873267 The degree of shaping is determined by the preoperative root dimension, the obturation technique, and the restorative treatment plan. Narrow thin roots such as the mandibular incisors cannot be enlarged to the same degree as more bulky roots such as the maxillary central incisors. Post placement is also a determining factor in the amount of coronal dentin removal. APICAL CANAL PREPARATION Termination of Cleaning and Shaping While the concept of cleaning and shaping the root canal space is a simple concept, there are areas where consensus does not exist. The first is the extent of the apical preparation. Early studies identified the dentinocemental junction as the area where the pulp ends and the periodontal ligament begins. Unfortunately, this is a histologic landmark and the position (which is irregular within the canal) cannot be determined clinically. Traditionally the apical point of termination has been one millimeter from the radiographic apex. In a classic study it was noted the apical portion of the canal consisted of the major diameter of the foramen and the minor diameter of the constriction (Figure 16-4). ADDIN EN.CITE Kuttler1955100271002717Kuttler, Y.Microscopic investigation of root apexesJ Am Dent AssocJ Am Dent Assoc544-52505ToothTeeth1955May0002-8177 (Print)143669348 The apical constriction is defined as the narrowest portion of the canal and the average distance from the foramen to the constriction was found to be 0.5 millimeters. One study found the classic apical constriction to be present in only 46% of the teeth and when present varied in relation to the apical foramen. ADDIN EN.CITE Dummer1984100261002617Dummer, P. M.McGinn, J. H.Rees, D. G.The position and topography of the apical canal constriction and apical foramenInt Endod JInt Endod J192-8174Comparative StudyDental Pulp Cavity/ anatomy & histologyHumansOdontometryTooth Root/ anatomy & histology1984Oct0143-2885 (Print)65933039 Variations from the classic appearance consist of the tapering constriction, the multiple constriction and the parallel constriction. ADDIN EN.CITE Dummer19849722972217Dummer, P. M.McGinn, J. H.Rees, D. G.The position and topography of the apical canal constriction and apical foramenInt Endod JInt Endod J192-8174Comparative StudyDental Pulp Cavity/ anatomy & histologyHumansOdontometryTooth Root/ anatomy & histology1984Oct0143-2885 (Print)65933039 Based on the variations in apical morphology, the term apical constriction is misnomer. To complicate the issue the foramen is seldom at the apex. Apical anatomy has also been shown to be quite variable (Figure 16-4). A recent study found no typical pattern for foraminal openings and that no foramen coincided with the apex of the root.  ADDIN EN.CITE Gutierrez1995100351003517Gutierrez, J. H.Aguayo, P.Faculty of Dentistry, University de Concepcion, Chile.Apical foraminal openings in human teeth. Number and locationOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod769-77796AdultAgedDental Pulp Cavity/ anatomy & histology/ultrastructureHumansMicroscopy, Electron, ScanningMiddle AgedResearch Support, Non-U.S. Gov'tTooth Root/ anatomy & histology/ultrastructure1995Jun1079-2104 (Print)762103810 The foramen to apex distance can range from .20 to 3.8 mm. ADDIN EN.CITE Gutierrez1995100351003517Gutierrez, J. H.Aguayo, P.Faculty of Dentistry, University de Concepcion, Chile.Apical foraminal openings in human teeth. Number and locationOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod769-77796AdultAgedDental Pulp Cavity/ anatomy & histology/ultrastructureHumansMicroscopy, Electron, ScanningMiddle AgedResearch Support, Non-U.S. Gov'tTooth Root/ anatomy & histology/ultrastructure1995Jun1079-2104 (Print)762103810 It has also been noted that the foramen to constriction distance increases with age ADDIN EN.CITE Kuttler1955100271002717Kuttler, Y.Microscopic investigation of root apexesJ Am Dent AssocJ Am Dent Assoc544-52505ToothTeeth1955May0002-8177 (Print)143669348 and root resorption may destroy the classic anatomical constriction. Resorption is common with pulp necrosis and apical bone resorption and this can result in loss of the constriction ADDIN EN.CITE Malueg1996100311003117Malueg, L. A.Wilcox, L. R.Johnson, W.Department of Endodontics, University of Iowa College of Dentistry, Iowa City, USA.Examination of external apical root resorption with scanning electron microscopyOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod89-93821Chi-Square DistributionComparative StudyDental Pulp Necrosis/complicationsHumansMicroscopy, Electron, ScanningOdontometry/methodsPeriapical Abscess/complicationsPeriapical Periodontitis/complicationsPulpitis/complicationsRoot Resorption/etiology/ pathologyStatistics, NonparametricTooth Apex/ ultrastructure1996Jul1079-2104 (Print)884346011 therefore root resorption is an additional factor to consider in length determination. In a recent prospective study evaluating prognosis, significant factors influencing success and failure were perforation, preoperative periradicular disease, and adequate length of the root canal filling. ADDIN EN.CITE Farzaneh2004100391003917Farzaneh, M.Abitbol, S.Friedman, S.Discipline of Endodtics, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6, Canada.Treatment outcome in endodontics: the Toronto study. Phases I and II: Orthograde retreatmentJ EndodJ Endod627-33309AdultCanadaEpidemiologic MethodsFemaleHumansMaleMiddle AgedPeriapical Periodontitis/ therapyProspective StudiesResearch Support, Non-U.S. Gov'tRetreatment/statistics & numerical dataRoot Canal Therapy/ statistics & numerical dataTreatment Outcome2004Sep0099-2399 (Print)1532956512 The authors speculated that canals filled more than 2.0 mm short harbored necrotic tissue, bacteria and irritants that when retreated could be cleaned and sealed.  ADDIN EN.CITE Farzaneh2004100391003917Farzaneh, M.Abitbol, S.Friedman, S.Discipline of Endodtics, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6, Canada.Treatment outcome in endodontics: the Toronto study. Phases I and II: Orthograde retreatmentJ EndodJ Endod627-33309AdultCanadaEpidemiologic MethodsFemaleHumansMaleMiddle AgedPeriapical Periodontitis/ therapyProspective StudiesResearch Support, Non-U.S. Gov'tRetreatment/statistics & numerical dataRoot Canal Therapy/ statistics & numerical dataTreatment Outcome2004Sep0099-2399 (Print)1532956512 A meta-analysis evaluation of success/failure indicated a better success rate when the obturation was confined to the canal space. ADDIN EN.CITE Schaeffer2005100411004117Schaeffer, M. A.White, R. R.Walton, R. E.Division of Endodontics, Harvard School of Dental Medicine, Boston, MA, USA. Parodocs@concentric.netDetermining the optimal obturation length: a meta-analysis of literatureJ EndodJ Endod271-4314Dental Pulp CavityDental Research/standardsDental Restoration FailureExtravasation of Diagnostic and Therapeutic MaterialsHumansOdontometryRegression AnalysisRoot Canal Obturation/ standardsTooth Apex2005Apr0099-2399 (Print)1579338213 A review of a number of prognosis studies confirms that extrusion of materials decreases success. ADDIN EN.CITE Wu2000100421004217Wu, M. K.Wesselink, P. R.Walton, R. E.Department of Cariology, Endodontology, Pedodontology, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands. M.Wu@acta.nlApical terminus location of root canal treatment proceduresOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod99-103891Comparative StudyDental Pulp Cavity/anatomy & histologyDental Pulp Necrosis/pathologyHumansPrognosisRetreatment/methodsRoot Canal Therapy/instrumentation/methodsTooth Apex/ anatomy & histology2000Jan1079-2104 (Print)1063095014 With pulp necrosis, better success was achieved when the procedures terminated at or within 2 mm of the radiographic apex. Obturation shorter than 2 mm from the apex or past the apex resulted in a decreased success rate. In teeth with vital inflamed pulp tissue, termination between 2-3 mm was acceptable. While the guideline of 1.0-2.0 mm from the radiographic apex remains rational, the point of apical termination of the preparation and obturation remains empirical. The need to compact the gutta-percha and sealer against the apical dentin matrix (constriction of the canal) is essential for success. The decision of where the minor diameter of the canal lies is based on knowledge of apical anatomy, tactile sensation, radiographic interpretation, apex locators, apical bleeding, and the patients response. To prevent extrusion, the cleaning and shaping procedures must be confined to the radicular space. Canals filled to the radiographic apex are actually overextended. ADDIN EN.CITE Gutierrez1995100351003517Gutierrez, J. H.Aguayo, P.Faculty of Dentistry, University de Concepcion, Chile.Apical foraminal openings in human teeth. Number and locationOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod769-77796AdultAgedDental Pulp Cavity/ anatomy & histology/ultrastructureHumansMicroscopy, Electron, ScanningMiddle AgedResearch Support, Non-U.S. Gov'tTooth Root/ anatomy & histology/ultrastructure1995Jun1079-2104 (Print)762103810 Degree of Apical Enlargement While generalizations can be made regarding tooth anatomy and morphology, each tooth is unique. Length of canal preparation is often emphasized with little consideration given to important factors such as canal diameter and shape. Since morphology is variable, there is no standardized apical canal size. Traditionally preparation techniques were determined by the desire to limit procedural errors and by the method of obturation. Small apical preparation limits canal transportation and apical zipping, but decreases the efficacy of the cleaning procedure. It appears that, with traditional hand files, apical transportation occurs in most curved canals enlarged beyond a size #25 stainless steel file. ADDIN EN.CITE Eldeeb19855518551817Eldeeb, M. E.Boraas, J. C.The effect of different files on the preparation shape of severely curved canalsInternational Endodontic JournalInternational Endodontic Journal1-71811985Jan385823415 The criteria for cleaning and shaping should be based on the ability to adequately remove the tissue, necrotic debris, and bacteria and not a specific obturation technique. Irrigants are unable to reach the apical portion of the root if the canal is not enlarged to a size #35 or #40 file. ADDIN EN.CITE Salzgeber19777548754817Salzgeber, R. M.Brilliant, J. D.An in vivo evaluation of the penetration of an irrigating solution in root canalsJournal of EndodonticsJournal of Endodontics394-83101977Oct270543Ram19777580758017Ram, Z.Effectiveness of root canal irrigationOral Surgery, Oral Medicine, Oral PathologyOral Surgery, Oral Medicine, Oral Pathology306-124421977Aug268582Chow19835848584817Chow, T. W.Mechanical effectiveness of root canal irrigationJournal of EndodonticsJournal of Endodontics475-99111983Nov658697516-18 The larger preparation sizes have been shown to provide adequate irrigation and debris removal as well as significantly decreasing the number of microorganisms. ADDIN EN.CITE Orstavik19913665366517Orstavik, D.Kerekes, K.Molven, O.Scandinavian Institute of Dental Materials, Haslum, Norway.Effects of extensive apical reaming and calcium hydroxide dressing on bacterial infection during treatment of apical periodontitis: a pilot studyInternational Endodontic JournalInternational Endodontic Journal1-72411991Jan1917083Dalton19982150215017Dalton, B. C.Orstavik, D.Phillips, C.Pettiette, M.Trope, M.Department of Orthodontics, University of North Carolina School of Dentistry, Chapel Hill 27599, USA.Bacterial reduction with nickel-titanium rotary instrumentationJournal of EndodonticsJournal of Endodontics763-724111998Nov9855830Sjogren19913610361017Sjogren, U.Figdor, D.Spangberg, L.Sundqvist, G.Department of Endodontics, University of Umea, Sweden.The antimicrobial effect of calcium hydroxide as a short-term intracanal dressingInternational Endodontic JournalInternational Endodontic Journal119-252431991May1778624Wu19923433343317Wu, Y. N.Shi, J. N.Huang, L. Z.Xu, Y. Y.Fourth Military Medical University, Xian, China.Variables affecting electronic root canal measurementInternational Endodontic JournalInternational Endodontic Journal88-922521992Mar139905719-22 Thus there appears to be a relationship between increasing the size of the apical preparation and canal cleanliness ADDIN EN.CITE Usman200455055017Usman, N.Baumgartner, J. C.Marshall, J. G.Department of Endodontology, Oregon Health and Sciences University School of Dentistry, Portland 97201, USA.Influence of instrument size on root canal debridementJournal of EndodonticsJournal of Endodontics110-23022004Feb1497730923 and bacterial reduction. ADDIN EN.CITE Card20021176117617Card, S. J.Sigurdsson, A.Orstavik, D.Trope, M.Department of Endodontics, The University of North Carolina, Chapel Hill 27599, USA.The effectiveness of increased apical enlargement in reducing intracanal bacteriaJournal of EndodonticsJournal of Endodontics779-8328112002Nov12470024Rollison20029756975617Rollison, S.Barnett, F.Stevens, R. H.Department of Endodontics, Temple University School of Dentistry, Philadelphia, PA 19140, USA.Efficacy of bacterial removal from instrumented root canals in vitro related to instrumentation technique and sizeOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod366-71943Colony Count, MicrobialComparative StudyDental AlloysDental InstrumentsDental Pulp Cavity/ microbiologyDentin/ microbiologyEnterococcus faecalis/isolation & purificationEquipment DesignHumansMolarNickelRoot Canal Preparation/ instrumentationSmear LayerStatistics, NonparametricTitaniumTritium/metabolism2002Sep1079-2104 (Print)1232479524, 25 Instrumentation techniques that advocate minimal apical preparation may be ineffective at achieving the goal of cleaning and disinfecting the root canal space. ADDIN EN.CITE Card2002100601006017Card, S. J.Sigurdsson, A.Orstavik, D.Trope, M.Department of Endodontics, The University of North Carolina, Chapel Hill 27599, USA.The effectiveness of increased apical enlargement in reducing intracanal bacteriaJ EndodJ Endod779-832811Bacteria/ growth & developmentBicuspidCuspidDental AlloysDental Pulp Cavity/anatomy & histology/ microbiologyDisinfectants/therapeutic useDisinfection/ methodsEquipment DesignHumansMolarNickelPeriapical Periodontitis/microbiology/therapyResearch Support, Non-U.S. Gov'tRoot Canal Irrigants/therapeutic useRoot Canal Preparation/instrumentation/ methodsSodium Hypochlorite/therapeutic useStatisticsStatistics, NonparametricTitaniumTooth Apex/anatomy & histology/ microbiology2002Nov0099-2399 (Print)12470024Usman200455055017Usman, N.Baumgartner, J. C.Marshall, J. G.Department of Endodontology, Oregon Health and Sciences University School of Dentistry, Portland 97201, USA.Influence of instrument size on root canal debridementJournal of EndodonticsJournal of Endodontics110-23022004Feb1497730926, 23 Bacteria can penetrate the tubules of dentin. These intratubular organisms are protected from endodontic instruments, the action of irrigants, and intracanal medicaments. Dentin removal appears to be the primary method for decreasing their numbers. In addition it may not be possible to remove bacteria that are deep in the tubules regardless of the technique. There is a correlation between the number of organisms present and the depth of tubular penetration; ADDIN EN.CITE Akpata19767721772117Akpata, E. S.Effect of endodontic procedures on the population of viable microorganisms in the infected root canalJournal of EndodonticsJournal of Endodontics369-732121976Dec106982827 in teeth with apical periodontitis, bacteria penetrate the tubules to the periphery of the root. ADDIN EN.CITE Peters20019771977117Peters, L. B.Wesselink, P. R.Buijs, J. F.van Winkelhoff, A. J.Department of Cariology, Endodontology, and Pedodontology, Academic Center for Dentistry Amsterdam, The Netherlands.Viable bacteria in root dentinal tubules of teeth with apical periodontitisJ EndodJ Endod76-81272Actinomyces/growth & developmentBacteria/ classification/growth & developmentBacteria, Anaerobic/growth & developmentBacteriological TechniquesBacteroides/growth & developmentColony Count, MicrobialCulture MediaDental Cementum/microbiologyDental Pulp/microbiologyDentin/ microbiology/ultrastructureFusobacterium/growth & developmentGram-Negative Bacteria/growth & developmentGram-Positive Cocci/growth & developmentGram-Positive Rods/growth & developmentHumansNetherlandsPeptostreptococcus/growth & developmentPeriapical Periodontitis/ microbiologyPorphyromonas/growth & developmentPrevotella/growth & developmentScotlandStatistics, NonparametricTooth Root/ microbiology/ultrastructure2001Feb0099-2399 (Print)11491642Matsuo20039772977217Matsuo, T.Shirakami, T.Ozaki, K.Nakanishi, T.Yumoto, H.Ebisu, S.Department of Conservative Dentistry, University of Tokushima School of Dentistry, Kuramoto, Japan.An immunohistological study of the localization of bacteria invading root pulpal walls of teeth with periapical lesionsJ EndodJ Endod194-200293AdultAgedBacteria/classification/ ultrastructureColoring Agents/diagnostic useDental Pulp/ microbiology/ultrastructureDentin/ microbiology/ultrastructureEubacterium/ultrastructureFusobacterium nucleatum/ultrastructureHumansImmune SeraImmunoenzyme TechniquesImmunohistochemistryLactobacillus casei/ultrastructureMiddle AgedPeptostreptococcus/ultrastructurePeriapical Diseases/ microbiology/pathologyPorphyromonas/ultrastructurePrevotella/ultrastructureResearch Support, Non-U.S. Gov'tRoot Canal PreparationStatistics, NonparametricTooth Root/ microbiology/ultrastructure2003Mar0099-2399 (Print)1266988028, 29 Elimination of Etiology The development of nickel titanium instruments has dramatically changed the techniques of cleaning and shaping. The primary advantage to using these flexible instruments is related to shaping. Neither hand instruments nor rotary files have been shown to completely debride the canal. ADDIN EN.CITE Dalton1998100681006817Dalton, B. C.Orstavik, D.Phillips, C.Pettiette, M.Trope, M.Department of Orthodontics, University of North Carolina School of Dentistry, Chapel Hill 27599, USA.Bacterial reduction with nickel-titanium rotary instrumentationJ EndodJ Endod763-72411Analysis of VarianceBacteria/isolation & purificationColony Count, MicrobialComparative StudyDental High-Speed TechniqueDental InstrumentsDental Pulp Cavity/ microbiologyEquipment DesignHumansNickelPeriapical Periodontitis/microbiologyResearch Support, Non-U.S. Gov'tRoot Canal Preparation/ instrumentation/methodsStainless SteelTitanium1998Nov0099-2399 (Print)9855830Waltimo2005100511005117Waltimo, T.Trope, M.Haapasalo, M.Orstavik, D.Institute of Dentistry, University of Turku, Turku, Finland, and Institute of Preventive Dentistry and Oral Microbiology, University of Basel, Basel, Switzerland.Clinical efficacy of treatment procedures in endodontic infection control and one year follow-up of periapical healingJ EndodJ Endod863-63112Calcium Hydroxide/therapeutic useChronic DiseaseDental Pulp Cavity/drug effects/microbiologyDisinfectants/therapeutic useFollow-Up StudiesGram-Negative Bacteria/growth & developmentGram-Positive Bacteria/growth & developmentHumansPeriapical Periodontitis/microbiology/ therapyRoot Canal Filling Materials/ therapeutic useRoot Canal Irrigants/ therapeutic useRoot Canal Preparation/ methodsSodium Hypochlorite/therapeutic useTreatment OutcomeWound Healing2005Dec0099-2399 (Print)16306819Shuping2000100621006217Shuping, G. B.Orstavik, D.Sigurdsson, A.Trope, M.Department of Endodontics, School of Dentistry, University of North Carolina, Chapel Hill 27599, USA.Reduction of intracanal bacteria using nickel-titanium rotary instrumentation and various medicationsJ EndodJ Endod751-52612AnaerobiosisAnalysis of VarianceBacteria/drug effects/ growth & developmentCalcium Hydroxide/therapeutic useChronic DiseaseColony Count, MicrobialComparative StudyDental AlloysDental Pulp Cavity/ microbiologyDisinfectants/ therapeutic useEquipment DesignFollow-Up StudiesHumansLinear ModelsNickelPeriapical Periodontitis/microbiology/therapyRoot Canal Filling Materials/therapeutic useRoot Canal Irrigants/ therapeutic useRoot Canal Preparation/ instrumentationSodium ChlorideSodium Hypochlorite/therapeutic useStatisticsTime FactorsTitanium2000Dec0099-2399 (Print)1147164830-32 Mechanical enlargement of the canal space dramatically decreases the presence of microorganisms present in the canal ADDIN EN.CITE Siqueira19992082208217Siqueira, J. F., Jr.Lima, K. C.Magalhaes, F. A.Lopes, H. P.de Uzeda, M.Estacio de Sa University, Rio de Janeiro, Brazil.Mechanical reduction of the bacterial population in the root canal by three instrumentation techniquesJournal of EndodonticsJournal of Endodontics332-52551999May1053025633 but cannot render the canal sterile. ADDIN EN.CITE Dalton19982150215017Dalton, B. C.Orstavik, D.Phillips, C.Pettiette, M.Trope, M.Department of Orthodontics, University of North Carolina School of Dentistry, Chapel Hill 27599, USA.Bacterial reduction with nickel-titanium rotary instrumentationJournal of EndodonticsJournal of Endodontics763-724111998Nov985583019 To improve the mechanical preparation techniques antimicrobial irrigants have been recommended. ADDIN EN.CITE Siqueira20021356135617Siqueira, J. F., Jr.Rjcas, I. N.Santos, S. R.Lima, K. C.Magalhaes, F. A.de Uzeda, M.Oral Microbiology Laboratory, Institute of Microbiology, Federal University of Rio de Janeiro, RJ, Brazil.Efficacy of instrumentation techniques and irrigation regimens in reducing the bacterial population within root canalsJournal of EndodonticsJournal of Endodontics181-42832002Mar1201717634 There is no consensus on the most appropriate irrigant or concentration of solution, although sodium hypochlorite is the most widely used irrigant. Common irrigants include sodium hypochlorite and chlorhexidine. ADDIN EN.CITE Orstavik19909762976217Orstavik, D.Haapasalo, M.Scandinavian Institute of Dental Materials, Oslo.Disinfection by endodontic irrigants and dressings of experimentally infected dentinal tubulesEndod Dent TraumatolEndod Dent Traumatol142-964AnimalsBacteria/growth & developmentBacterial Infections/ drug therapyCattleDental Pulp Diseases/ drug therapyDentin/ ultrastructureMicroscopy, Electron, ScanningRoot Canal Irrigants/ therapeutic useSmear Layer1990Aug0109-2502 (Print)2133305Siqueira20022088208817Siqueira, J. F., Jr.Rocas, I. N.Santos, S. R.Lima, K. C.Magalhaes, F. A.de Uzeda, M.Oral Microbiology Laboratory, Institute of Microbiology, Federal University of Rio de Janeiro, RJ, Brazil.Efficacy of instrumentation techniques and irrigation regimens in reducing the bacterial population within root canalsJournal of EndodonticsJournal of Endodontics181-42832002Mar12017176Heling19989782978217Heling, I.Chandler, N. P.Department of Endodontics, Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel.Antimicrobial effect of irrigant combinations within dentinal tubulesInt Endod JInt Endod J8-14311AnimalsCattleChlorhexidine/pharmacologyComparative StudyDentin/ microbiologyDrug CombinationsEdetic Acid/pharmacologyEnterococcus faecalis/drug effectsEvaluation StudiesHydrogen Peroxide/pharmacologyRoot Canal Irrigants/ pharmacologySodium Hypochlorite/pharmacology1998Jan0143-2885 (Print)9823123Tanomaru Filho20021338133817Tanomaru Filho, M.Leonardo, M. R.da Silva, L. A.Department of Endodontics, School of Dentistry of Araraquara, University of the State of Sao Paulo, UNESP, Brazil.Effect of irrigating solution and calcium hydroxide root canal dressing on the repair of apical and periapical tissues of teeth with periapical lesionJournal of EndodonticsJournal of Endodontics295-92842002Apr12043867Haenni20039838983817Haenni, S.Schmidlin, P. R.Mueller, B.Sener, B.Zehnder, M.Division of Endodontology, Department of Preventive Dentistry, Cariology, and Periodontology, Center for Dental Medicine, University of Zurich, Switzerland.Chemical and antimicrobial properties of calcium hydroxide mixed with irrigating solutionsInt Endod JInt Endod J100-5362Analysis of VarianceAnti-Infective Agents, Local/ pharmacologyBicuspidCalcium Hydroxide/ pharmacologyCandida albicans/drug effectsChlorhexidine/ analogs & derivatives/pharmacologyCuspidDental Pulp Cavity/drug effectsDrug CombinationsEnterococcus faecalis/drug effectsHumansHydrogen-Ion Concentration/drug effectsImmunodiffusionIodine Compounds/pharmacologyRoot Canal Filling Materials/ pharmacologyRoot Canal Irrigants/ pharmacologyStatistics, Nonparametric2003Feb0143-2885 (Print)1265715335-39 Unfortunately solutions designed to kill bacteria are often toxic for the host cells, ADDIN EN.CITE Pashley1985100701007017Pashley, E. L.Birdsong, N. L.Bowman, K.Pashley, D. H.Cytotoxic effects of NaOCl on vital tissueJ EndodJ Endod525-81112AnimalsEdema/chemically inducedErythrocytes/drug effectsEye/drug effectsFemaleHemolysisHemorrhage/chemically inducedHumansMaleRabbitsRatsResearch Support, U.S. Gov't, P.H.S.Skin/drug effectsSkin Diseases/chemically inducedSodium Hypochlorite/ pharmacology1985Dec0099-2399 (Print)3867719Witton2005100851008517Witton, R.Brennan, P. A.Oral and Maxillofacial Surgery, Queen Alexandra Hospital, Portsmouth. rvwitton@hotmail.co.ukSevere tissue damage and neurological deficit following extravasation of sodium hypochlorite solution during routine endodontic treatmentBr Dent JBr Dent J749-5019812AdultAnti-Inflammatory Agents/administration & dosageBurns, Chemical/drug therapy/ etiologyDexamethasone/administration & dosageExtravasation of Diagnostic and Therapeutic Materials/ complicationsFacial Injuries/drug therapy/etiologyFacial Nerve Injuries/ etiologyFemaleHumansInjections, IntravenousMouth Mucosa/injuries/pathologyNecrosisRoot Canal Irrigants/ adverse effectsSodium Hypochlorite/ adverse effects2005Jun 250007-0610 (Print)15980834Gernhardt2004100831008317Gernhardt, C. R.Eppendorf, K.Kozlowski, A.Brandt, M.Department of Operative Dentistry and Periodontology, University School of Dental Medicine, Martin-Luther-University, Halle, Germany. christian.gernhardt@medizin.uni-halle.deToxicity of concentrated sodium hypochlorite used as an endodontic irrigantInt Endod JInt Endod J272-80374Dental Pulp Cavity/anatomy & histologyExtravasation of Diagnostic and TherapeuticMaterials/complications/etiologyFemaleHematoma/chemically inducedHumansLip/ drug effects/injuries/pathologyMiddle AgedMouth Mucosa/ drug effects/injuries/pathologyNecrosisOdontometryRoot Canal Irrigants/administration & dosage/ adverse effectsRoot Resorption/complicationsSodium Hypochlorite/administration & dosage/ adverse effects2004Apr0143-2885 (Print)15056354Reeh1989100741007417Reeh, E. S.Messer, H. H.Long-term paresthesia following inadvertent forcing of sodium hypochlorite through perforation in maxillary incisorEndod Dent TraumatolEndod Dent Traumatol200-354AdultFemaleHumansIncisorParesthesia/ chemically inducedRoot Canal Irrigants/ adverse effectsSodium Hypochlorite/ adverse effects1989Aug0109-2502 (Print)263786140-43 so extrusion beyond the canal space therefore is to be avoided. ADDIN EN.CITE Hulsmann20009781978117Hulsmann, M.Hahn, W.Department of Operative Dentistry, University of Gottingen, Robert-Koch-Str. 40, D-37075 Gottingen.Complications during root canal irrigation--literature review and case reportsInt Endod JInt Endod J186-93333AnimalsBurns, Chemical/etiologyExtravasation of Diagnostic and Therapeutic Materials/etiologyEye Burns/etiologyFemaleHumansHydrogen Peroxide/adverse effectsHypersensitivity/etiologyMaleMiddle AgedOral Hemorrhage/etiologyRoot Canal Irrigants/ adverse effectsSodium Hypochlorite/ adverse effectsSubcutaneous Emphysema/etiology2000May0143-2885 (Print)11307434Brown19952903290317Brown, D. C.Moore, B. K.Brown, C. E., Jr.Newton, C. W.Department of Endodontics, Indiana University School of Dentistry, Indianapolis, Indiana 46202, USA.An in vitro study of apical extrusion of sodium hypochlorite during endodontic canal preparationJournal of EndodonticsJournal of Endodontics587-9121121995Dec859607744, 45 A major factor related to effectiveness is the volume. Increasing the volume produces cleaner preparations. ADDIN EN.CITE Yamada19836066606617Yamada, R. S.Armas, A.Goldman, M.Lin, P. S.A scanning electron microscopic comparison of a high volume final flush with several irrigating solutions: Part 3Journal of EndodonticsJournal of Endodontics137-42941983Apr640663546 Apical Patency Apical patency has been advocated during cleaning and shaping procedures to ensure working length is not lost and that the apical portion of the root is not packed with tissue, dentin debris and bacteria (Figure 16-5). Concerns regarding extrusion of dentinal debris, bacteria and irrigants have been raised. ADDIN EN.CITE Lambrianidis20011476147617Lambrianidis, T.Tosounidou, E.Tzoanopoulou, M.Department of Endodontology, School of Dentistry, Aristotle University, Thessaloniki, Greece.The effect of maintaining apical patency on periapical extrusionJournal of EndodonticsJournal of Endodontics696-827112001Nov1171608447 Seeding the periradicular tissues with microorganisms may occur. ADDIN EN.CITE Debelian1995101021010217Debelian, G. J.Olsen, I.Tronstad, L.Division of Endodontics, Department of Oral Biology, Faculty of Dentistry, University of Oslo, Norway.Bacteremia in conjunction with endodontic therapyEndod Dent TraumatolEndod Dent Traumatol142-9113Actinomyces/isolation & purificationBacteremia/ etiology/microbiologyChi-Square DistributionDental Pulp Cavity/ microbiologyEubacterium/isolation & purificationFusobacterium nucleatum/isolation & purificationGram-Negative Anaerobic Bacteria/isolation & purificationGram-Negative Facultatively Anaerobic Rods/isolation & purificationHumansPeptostreptococcus/isolation & purificationPeriapical Periodontitis/complications/ microbiology/therapyPrevotella/isolation & purificationPropionibacterium/isolation & purificationRoot Canal Therapy/ adverse effectsSaccharomyces cerevisiae/isolation & purificationStreptococcus/isolation & purification1995Jun0109-2502 (Print)764163148 Studies evaluating treatment failure have noted bacteria outside the radicular space, ADDIN EN.CITE Nair2005100961009617Nair, P. N.Henry, S.Cano, V.Vera, J.Institute of Oral Biology, Center of Dental & Oral Medicine, University of Zurich, Zurich, Switzerland. nair@zzmk.unizh.chMicrobial status of apical root canal system of human mandibular first molars with primary apical periodontitis after "one-visit" endodontic treatmentOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod231-52992AdolescentAdultAgedApicoectomyBiofilmsDental Pulp Cavity/ microbiologyEdetic Acid/therapeutic useFemaleGutta-Percha/therapeutic useHumansMaleMicroscopy, Electron, TransmissionMiddle AgedMolar/ microbiologyPeriapical Periodontitis/ microbiologyRoot Canal Filling Materials/therapeutic useRoot Canal Irrigants/therapeutic useRoot Canal Preparation/instrumentationRoot Canal TherapySodium Hypochlorite/therapeutic useTooth Apex/ microbiologyZinc Oxide-Eugenol Cement/therapeutic use2005Feb1079-2104 (Print)15660098Nair2006100951009517Nair, P. N.Institute of Oral Biology, Section of Oral Structures and Development, Centre of Dental and Oral Medicine, University of Zurich, Zurich, Switzerland. nair@zzmk.unizh.chOn the causes of persistent apical periodontitis: a reviewInt Endod JInt Endod J249-81394Actinomycosis/complicationsBacterial Infections/complicationsCholesterolChronic DiseaseCicatrix/complicationsCrystallizationDental Restoration FailureExtravasation of Diagnostic and Therapeutic Materials/complicationsForeign Bodies/complicationsHumansPeriapical Periodontitis/ etiologyRadicular Cyst/complicationsRoot Canal Therapy/adverse effects2006Apr0143-2885 (Print)1658448949, 50 and bacteria have been shown to exist as plaques or biofilms on the root external root structure. ADDIN EN.CITE Tronstad1990101041010417Tronstad, L.Barnett, F.Cervone, F.Department of Endodontics, University of Pennsylvania School of Dental Medicine, Philadelphia.Periapical bacterial plaque in teeth refractory to endodontic treatmentEndod Dent TraumatolEndod Dent Traumatol73-762Bacteria/isolation & purificationBacteroides/isolation & purificationDental Plaque/ microbiologyHumansMicroscopy, Electron, ScanningPeriapical Abscess/microbiologyPeriapical Diseases/ microbiologyTooth Root/ microbiology1990Apr0109-2502 (Print)213221351 The apical patency concept also has been advocated to facilitate apical preparation. Extending the file beyond the apex increases the diameter of the canal at working length consistent with the instrument taper. The value of maintaining patency to prevent transportation is questionable ADDIN EN.CITE Goldberg20021279127917Goldberg, F.Massone, E. J.Department of Endodontics, School of Dentistry, USAL-AOA, Buenos Aires, Argentina.Patency file and apical transportation: an in vitro studyJournal of EndodonticsJournal of Endodontics510-12872002Jul1212637752 and it does not result in bacterial reduction when compared to not maintaining patency. ADDIN EN.CITE Coldero2002100911009117Coldero, L. G.McHugh, S.MacKenzie, D.Saunders, W. P.Dental School, University of Glasgow, UK.Reduction in intracanal bacteria during root canal preparation with and without apical enlargementInt Endod JInt Endod J437-46355Analysis of VarianceChelating Agents/therapeutic useColony Count, MicrobialComparative StudyConfidence IntervalsDental AlloysDental Pulp Cavity/ microbiology/ultrastructureDentin/ultrastructureDisinfectants/therapeutic useEdetic Acid/therapeutic useEnterococcus faecalis/drug effects/growth & development/ isolation &purificationEquipment DesignHumansLinear ModelsLogistic ModelsMicroscopy, Electron, ScanningMolarNickelPilot ProjectsRoot Canal Irrigants/therapeutic useRoot Canal Preparation/instrumentation/ methodsSodium Hypochlorite/therapeutic useStatisticsThiosulfates/therapeutic useTitaniumTooth Apex/ ultrastructure2002May0143-2885 (Print)1205991553 Small files are not effective in debridement (Figure 16-3). PRETREATMENT EVALAUTION Prior to treatment, each case should be evaluated for degree of difficulty. Normal anatomy as well as anatomic variations are determined as well as variations in canal morphology (shape). A parallel preoperative radiograph or image is assessed. The longer a root, the more difficult it is to treat. Apically, a narrow curved root is susceptible to perforation; in multi-rooted teeth a narrow area mid root could lead to a lateral stripping perforation. The degree and location of curvature is determined. Canals are seldom straight and curvatures in a facial-lingual direction will not be visible on the radiograph. Sharp curvatures or dilacerations are more difficult to manage than a continuous gentle curve. Roots with an S-shape or bayonet configuration are difficult to treat. Calcifications will also complicate treatment. Calcification generally occurs in a coronal to apical direction (See Chapter 15, Figure 15-14). A large tapering canal may become more cylindrical with irritation or age. This presents problems when the tapered instruments are used in the coronal third. Resorption also will complicate treatment. With internal resorption it is difficult to pass instruments through the coronal portion of the canal, through the defect and into the apical portion. Also files will not remove tissue, necrotic debris and bacteria from this inaccessible area. External resorptions may perforate the canal space and present problems with hemostasis and isolation. Restorations may obstruct access and visibility as well as change the orientation of the crown in relation to the root. PRINCIPLES OF CLEANING AND SHAPING Cleaning and shaping are separate and distinct concepts but are performed concurrently. The criteria of canal preparation include: developing a continuously tapered funnel, maintaining the original shape of the canal, maintaining the apical foramen in its original position, keeping the apical opening as small as possible, and developing glassy smooth walls ADDIN EN.CITE Schilder19748147814717Schilder, H.Cleaning and shaping the root canalDental Clinics of North AmericaDental Clinics of North America269-961821974Apr45225706. The cleaning and shaping procedures are designed maintain an apical matrix for compacting the obturating material regardless of the obturation technique. ADDIN EN.CITE Schilder19748147814717Schilder, H.Cleaning and shaping the root canalDental Clinics of North AmericaDental Clinics of North America269-961821974Apr45225706 Knowledge of variety of techniques and instruments for treatment of the myriad variations in canal anatomy is required. There is no consensus on which technique or instrument is superior. ADDIN EN.CITE Dalton1998100681006817Dalton, B. C.Orstavik, D.Phillips, C.Pettiette, M.Trope, M.Department of Orthodontics, University of North Carolina School of Dentistry, Chapel Hill 27599, USA.Bacterial reduction with nickel-titanium rotary instrumentationJ EndodJ Endod763-72411Analysis of VarianceBacteria/isolation & purificationColony Count, MicrobialComparative StudyDental High-Speed TechniqueDental InstrumentsDental Pulp Cavity/ microbiologyEquipment DesignHumansNickelPeriapical Periodontitis/microbiologyResearch Support, Non-U.S. Gov'tRoot Canal Preparation/ instrumentation/methodsStainless SteelTitanium1998Nov0099-2399 (Print)985583030 Nickel-titanium files have been incorporated into endodontics due to their flexibility and resistance to and cyclic fatigue. ADDIN EN.CITE Walia19884480448017Walia, H. M.Brantley, W. A.Gerstein, H.An initial investigation of the bending and torsional properties of Nitinol root canal filesJournal of EndodonticsJournal of Endodontics346-511471988Jul325199654 The resistance to cyclic fatigue permits the instruments to be used in a rotary handpiece, an advantage over stainless steel. The instruments are manufactured in both hand and rotary versions. Both have been demonstrated to produce superior shaping when compared to stainless steel hand instruments. ADDIN EN.CITE Gambill19962725272517Gambill, J. M.Alder, M.del Rio, C. E.Department of Endodontics, Wilford Hall U.S. Air Force Medical Center, Lackland Air Force Base, TX, USA.Comparison of nickel-titanium and stainless steel hand-file instrumentation using computed tomographyJournal of EndodonticsJournal of Endodontics369-752271996Jul8935064Pettiette2001102621026217Pettiette, M. T.Delano, E. O.Trope, M.Department of Endodontics, University of North Carolina Schol of Dentistry, Chapel Hill 27599-7450, USA.Evaluation of success rate of endodontic treatment performed by students with stainless-steel K-files and nickel-titanium hand filesJ EndodJ Endod124-7272Comparative StudyDensitometry, X-RayDental AlloysDental Pulp Cavity/pathology/radiographyEndodontics/educationEquipment DesignFollow-Up StudiesHumansImage Processing, Computer-AssistedMolarNickelPeriapical Tissue/pathology/radiographyPrognosisRadiographic Image EnhancementReproducibility of ResultsRoot Canal Preparation/ instrumentationRoot Canal TherapyStainless SteelStatisticsStudents, DentalTitaniumTreatment FailureTreatment OutcomeWound Healing2001Feb0099-2399 (Print)1149163655, 56 The instruments are designed with increased taper when compared to .02 mm standardized stainless steel files. Common tapers are .04, .06, .08, .10, and .12 and the tip diameters may or may not conform to the traditional manufacturing specifications. The file systems can vary the taper while maintaining the same tip diameter or they can employ varied tapers with ISO standardized tip diameters. They may incorporate cutting or non-cutting tips. In general the nickel titanium rotary instruments are not indicated in S-shaped canals, canals that join within a single root (Type II configuration), in canals with severe dilacerations, canals in which ledge formation is present, and very large canals where they fail to contact the canal walls. Straight line access to the canal is essential and the instruments should be used passively. Instrument fracture can occur due to torsional forces or cyclic fatigue. Torsional forces develop due to frictional resistance, therefore as the surface area increases along the flutes the greater friction and more potential for fracture. Torsional forces may produce an unraveling of the flutes prior to fracture and inspection of the instruments after each use is critical. Torsional stress can be reduced by limiting file contact, by using a crown down preparation technique, and by lubrication. Cyclic fatigue occurs as the file rotates in a curved canal. ADDIN EN.CITE Pruett19972562256217Pruett, J. P.Clement, D. J.Carnes, D. L., Jr.Department of Endodontics/Dental School, University of Texas Health Science Center, San Antonio 78284-7898, USA.Cyclic fatigue testing of nickel-titanium endodontic instrumentsJournal of EndodonticsJournal of Endodontics77-852321997Feb922073557 At the point of curvature the molecules on the outer surface of the file are under tension while the molecules on the inner surface of the instrument are compressed. As the instrument rotates the areas of tension and compression alternate and eventual fracture occurs. There is no visible evidence that fracture is imminent. Therefore it is advised that the use of nickel titanium instruments be monitored ADDIN EN.CITE Zuolo1997102661026617Zuolo, M. L.Walton, R. E.Ensino Odontologico Institute, Sao Paulo, Brazil.Instrument deterioration with usage: nickel-titanium versus stainless steelQuintessence IntQuintessence Int397-402286Comparative StudyDental AlloysDental InstrumentsEquipment FailureEquipment Failure AnalysisMicroscopy, Electron, ScanningNickelStainless SteelSurface PropertiesTitanium1997Jun0033-6572 (Print)947790458 and limited to one to five cases. For difficult cases or calcified canals it is recommended the instruments be used only once. Ultrasonics Ultrasonics are used for cleaning and shaping, removal of materials from the canal, removal of posts and silver cones, thermoplastic obturation, and root end preparation during surgery. The main advantage to cleaning and shaping with ultrasonics is acoustic micro streaming. ADDIN EN.CITE Ahmad19874725472517Ahmad, M.Pitt Ford, T. J.Crum, L. A.Ultrasonic debridement of root canals: acoustic streaming and its possible roleJournal of EndodonticsJournal of Endodontics490-913101987Oct348222659 This is described as a complex steady-state streaming patterns in a vortex like motion or eddy flows formed close to the instrument. Agitation of the irrigant with an ultrasonically activated file after completion of cleaning and shaping has the benefit of increasing the effectiveness of the solution. ADDIN EN.CITE Archer19923374337417Archer, R.Reader, A.Nist, R.Beck, M.Meyers, W. J.Naval Hospital, Portsmouth.An in vivo evaluation of the efficacy of ultrasound after step-back preparation in mandibular molarsJournal of EndodonticsJournal of Endodontics549-5218111992Nov1298792Cameron19835959595917Cameron, J. A.The use of ultrasonics in the removal of the smear layer: a scanning electron microscope studyJournal of EndodonticsJournal of Endodontics289-92971983Jul6579185Weller19806882688217Weller, R. N.Brady, J. M.Bernier, W. E.Efficacy of ultrasonic cleaningJournal of EndodonticsJournal of Endodontics740-3691980Sep6935384Krell19884608460817Krell, K. V.Johnson, R. J.Madison, S.Irrigation patterns during ultrasonic canal instrumentation. Part I. K-type filesJournal of EndodonticsJournal of Endodontics65-81421988Feb316294160-63 Initially it was proposed that ultrasonics could clean the canal without procedural errors such as apical transportation and remove the smear layer. ADDIN EN.CITE Cunningham1982100161001617Cunningham, W. T.Martin, H.A scanning electron microscope evaluation of root canal debridement with the endosonic ultrasonic synergistic systemOral Surg Oral Med Oral PatholOral Surg Oral Med Oral Pathol527-31535Comparative StudyDebridement/methodsDental Pulp Cavity/ ultrastructureEvaluation StudiesHumansIrrigation/methodsMicroscopy, Electron, ScanningResearch Support, U.S. Gov't, Non-P.H.S.Root Canal Therapy/instrumentation/ methodsUltrasonics1982May0030-4220 (Print)6954428Cunningham19826535653517Cunningham, W. T.Martin, H.Forrest, W. R.Evaluation of root canal debridement by the endosonic ultrasonic synergistic systemOral Surgery, Oral Medicine, Oral PathologyOral Surgery, Oral Medicine, Oral Pathology401-45341982Apr695215264, 65 However later studies failed to confirm these results. ADDIN EN.CITE Chenail19884486448617Chenail, B. L.Teplitsky, P. E.Endosonics in curved root canals. Part IIJournal of EndodonticsJournal of Endodontics214-71451988May3251975Schulz-Bongert2861286117Schulz-Bongert, U.Weine, F. S.Schulz-Bongert, J.Endodontics Loyola University School of Dentistry, USA.Preparation of curved canals using a combined hand-filing, ultrasonic techniqueCompendium of Continuing Education in DentistryCompendium of Continuing Education in Dentistry270163274 passim; quiz 286, 1995 Mar8934999Cymerman1983100231002317Cymerman, J. J.Jerome, L. A.Moodnik, R. M.A scanning electron microscope study comparing the efficacy of hand instrumentation with ultrasonic instrumentation of the root canalJ EndodJ Endod327-3198Comparative StudyDental Pulp Cavity/ ultrastructureHumansMicroscopy, Electron, ScanningRoot Canal Therapy/ instrumentation/methodsUltrasonics/ instrumentation1983Aug0099-2399 (Print)657919066-68 IRRIGANTS AND LUBRICANTS The ideal properties for an endodontic irrigant are listed in Box-2. ADDIN EN.CITE Torabinejad20021179117917Torabinejad, M.Handysides, R.Khademi, A. A.Bakland, L. K.Department of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.Clinical implications of the smear layer in endodontics: a reviewOral Surgery Oral Medicine Oral Pathology Oral Radiology & EndodonticsOral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics658-669462002Dec1246488769 Currently no solution meets all the requirements outlined. Irrigation does not completely debride the canal. Sodium hypochlorite will not remove tissue from areas that are not touched by files (Figures 16-1 and 16-2). ADDIN EN.CITE Walton19767738773817Walton, R. E.Histologic evaluation of different methods of enlarging the pulp canal spaceJournal of EndodonticsJournal of Endodontics304-112101976Oct106820770 In fact no techniques appear able to completely clean the root canal space. ADDIN EN.CITE Wu19923433343317Wu, Y. N.Shi, J. N.Huang, L. Z.Xu, Y. Y.Fourth Military Medical University, Xian, China.Variables affecting electronic root canal measurementInternational Endodontic JournalInternational Endodontic Journal88-922521992Mar1399057Wu19959737973717Wu, M. K.Wesselink, P. R.Department of Cariology and Endodontology, Academic Centre For Dentistry, Amsterdam, The Netherlands.Efficacy of three techniques in cleaning the apical portion of curved root canalsOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod492-6794Comparative StudyDental Pulp Cavity/anatomy & histologyHumansMolarPressureRoot Canal IrrigantsRoot Canal Therapy/ instrumentation/ methodsRotationTooth Root/anatomy & histology1995Apr1079-2104 (Print)7614212Siqueira19979754975417Siqueira, J. F., Jr.Araujo, M. C.Garcia, P. F.Fraga, R. C.Dantas, C. J.Gama Filho School of Dentistry, Rio de Janeiro, Brazil.Histological evaluation of the effectiveness of five instrumentation techniques for cleaning the apical third of root canalsJ EndodJ Endod499-502238Comparative StudyDental AlloysDental Pulp Cavity/ pathologyEvaluation StudiesHumansIn VitroMandibleMolar/pathologyNickelRoot Canal Preparation/ instrumentation/methods/statistics & numericaldataStainless SteelStatistics, NonparametricTitaniumTooth Apex/ pathologyUltrasonic Therapy/instrumentation/methods/statistics & numerical data1997Aug0099-2399 (Print)9587319Tan20021231123117Tan, B. T.Messer, H. H.School of Dental Science, The University of Melbourne, Victoria, Australia.The quality of apical canal preparation using hand and rotary instruments with specific criteria for enlargement based on initial apical file sizeJournal of EndodonticsJournal of Endodontics658-642892002Sep1223631171-73, 22 Frequent irrigation is necessary to flush and remove the debris generated by the mechanical action of the instruments. Box-2 Properties of an ideal irrigant Organic tissue solvent Inorganic tissue solvent Antimicrobial action Non-toxic Low Surface Tension Lubricant Antimicrobial action Sodium Hypochlorite The most common irrigant is sodium hypochlorite (household bleach). Advantages to sodium hypochlorite include the mechanical flushing of debris from the canal, the ability of the solution to dissolve vital ADDIN EN.CITE Rosenfeld19787372737217Rosenfeld, E. F.James, G. A.Burch, B. S.Vital pulp tissue response to sodium hypochloriteJournal of EndodonticsJournal of Endodontics140-6451978May28318074 and necrotic tissue, ADDIN EN.CITE Svec19777622762217Svec, T. A.Harrison, J. W.Chemomechanical removal of pulpal and dentinal debris with sodium hypochlorite and hydrogen peroxide vs normal saline solutionJournal of EndodonticsJournal of Endodontics49-53321977Feb26493375 the antimicrobial action of the solution, ADDIN EN.CITE Waltimo20059758975817Waltimo, T.Trope, M.Haapasalo, M.Orstavik, D.Institute of Dentistry, University of Turku, Turku, Finland, and Institute of Preventive Dentistry and Oral Microbiology, University of Basel, Basel, Switzerland.Clinical efficacy of treatment procedures in endodontic infection control and one year follow-up of periapical healingJ EndodJ Endod863-63112Calcium Hydroxide/therapeutic useChronic DiseaseDental Pulp Cavity/drug effects/microbiologyDisinfectants/therapeutic useFollow-Up StudiesGram-Negative Bacteria/growth & developmentGram-Positive Bacteria/growth & developmentHumansPeriapical Periodontitis/microbiology/ therapyRoot Canal Filling Materials/ therapeutic useRoot Canal Irrigants/ therapeutic useRoot Canal Preparation/ methodsSodium Hypochlorite/therapeutic useTreatment OutcomeWound Healing2005Dec0099-2399 (Print)1630681932 and the lubricating action. ADDIN EN.CITE Peters20059812981217Peters, O. A.Boessler, C.Zehnder, M.Division of Endodontology, Department of Preventive Dentistry, Periodontology, and Cariology, University of Zurich Center for Dental Medicine, Zurich, Switzerland.Effect of liquid and paste-type lubricants on torque values during simulated rotary root canal instrumentationInt Endod JInt Endod J223-9384Analysis of VarianceComparative StudyDental InstrumentsDental Stress AnalysisEdetic AcidHumansLubricationMaterials TestingMolarRoot Canal IrrigantsRoot Canal Preparation/ instrumentationTorque2005Apr0143-2885 (Print)1581097276 In addition it is inexpensive and readily available. Free chlorine in sodium hypochlorite dissolves necrotic tissue by breaking down proteins into amino acids. There is no proven appropriate concentration of sodium hypochlorite, but concentrations ranging form 0.5% to 5.25% have been recommended. A common concentration is 2.5%; which decreases the potential for toxicity while still maintaining some tissue dissolving and antimicrobial activity. ADDIN EN.CITE Zehnder20029839983917Zehnder, M.Kosicki, D.Luder, H.Sener, B.Waltimo, T.Department of Preventive Dentistry, Cariology, and Periodontology, Center for Dental Medicine, University of Zurich, Switzerland. zehnder@zzmk.unizh.chTissue-dissolving capacity and antibacterial effect of buffered and unbuffered hypochlorite solutionsOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod756-62946Analysis of VarianceAnimalsAnti-Infective Agents, Local/pharmacologyBuffersComparative StudyDrug CombinationsEnterococcus faecalis/drug effectsMouth Mucosa/drug effectsRoot Canal Irrigants/chemistry/ pharmacologySodium Bicarbonate/pharmacologySodium Hypochlorite/chemistry/ pharmacologySwine2002Dec1079-2104 (Print)12464903Zehnder20069829982917Zehnder, M.Department of Preventive Dentistry, Periodontology, and Cariology, Division of Endodontology, University of Zurich Center for Dental Medicine, Switzerland. matthias.zehnder@zzmk.unizh.chRoot canal irrigantsJ EndodJ Endod389-98325Anti-Infective Agents, Local/pharmacologyBacteria, Anaerobic/drug effectsChelating Agents/pharmacologyChlorhexidine/pharmacologyDental Pulp Cavity/microbiologyEdetic Acid/pharmacologyHumansRoot Canal Irrigants/chemistry/pharmacologyRoot Canal Preparation/methodsSmear LayerSodium Hypochlorite/pharmacology2006May0099-2399 (Print)1663183477, 78 Since the action of the irrigant is related to the amount of free chlorine, decreasing the concentration can be compensated by increasing the volume. Warming the solution can also increase effectiveness of the solution. ADDIN EN.CITE Berutti1996100241002417Berutti, E.Marini, R.Department of Endodontics, School of Dentistry, Turin University, Torino, Italy.A scanning electron microscopic evaluation of the debridement capability of sodium hypochlorite at different temperaturesJ EndodJ Endod467-70229Comparative StudyDental Pulp Cavity/drug effects/ultrastructureHeatHumansIncisorMaxillaMicroscopy, Electron, ScanningRoot Canal Irrigants/ administration & dosageRoot Canal Preparation/instrumentation/methodsSmear LayerSodium Hypochlorite/ administration & dosage1996Sep0099-2399 (Print)9198427Gambarini1998100251002517Gambarini, G.De Luca, M.Gerosa, R.Department of Dental Materials, University of Siena, Dental School, Italy.Chemical stability of heated sodium hypochlorite endodontic irrigantsJ EndodJ Endod432-4246Analysis of VarianceChlorine/analysisDrug StabilityDrug StorageHeatHydrogen-Ion ConcentrationRoot Canal Irrigants/ chemistrySodium Hypochlorite/ chemistryTime Factors1998Jun0099-2399 (Print)969358979, 80 Because of toxicity, extrusion is to be avoided. ADDIN EN.CITE Hulsmann20009781978117Hulsmann, M.Hahn, W.Department of Operative Dentistry, University of Gottingen, Robert-Koch-Str. 40, D-37075 Gottingen.Complications during root canal irrigation--literature review and case reportsInt Endod JInt Endod J186-93333AnimalsBurns, Chemical/etiologyExtravasation of Diagnostic and Therapeutic Materials/etiologyEye Burns/etiologyFemaleHumansHydrogen Peroxide/adverse effectsHypersensitivity/etiologyMaleMiddle AgedOral Hemorrhage/etiologyRoot Canal Irrigants/ adverse effectsSodium Hypochlorite/ adverse effectsSubcutaneous Emphysema/etiology2000May0143-2885 (Print)11307434Pashley19859840984017Pashley, E. L.Birdsong, N. L.Bowman, K.Pashley, D. H.Cytotoxic effects of NaOCl on vital tissueJ EndodJ Endod525-81112AnimalsEdema/chemically inducedErythrocytes/drug effectsEye/drug effectsFemaleHemolysisHemorrhage/chemically inducedHumansMaleRabbitsRatsResearch Support, U.S. Gov't, P.H.S.Skin/drug effectsSkin Diseases/chemically inducedSodium Hypochlorite/ pharmacology1985Dec0099-2399 (Print)3867719Oncag20031044104417Oncag, O.Hosgor, M.Hilmioglu, S.Zekioglu, O.Eronat, C.Burhanoglu, D.Department of Pedodontics, Dental Faculty, Ege University, Bornova, Izmir, Turkey. oncag@egenet.com.trComparison of antibacterial and toxic effects of various root canal irrigantsInternational Endodontic JournalInternational Endodontic Journal423-323662003Jun1280129045, 81, 41 The irrigating needle must be placed loosely in the canal (Figure 16-6). Insertion to binding and slight withdrawal minimizes the potential for possible extrusion and a sodium hypochlorite accident (Figure 16-7). Special care should be exercised when irrigating a canal with an open apex. To control the depth of insertion the needle is bent slightly at the appropriate length or a rubber stopper placed on the needle. The irrigant does not move apically more than one millimeter beyond the irrigation tip so deep placement with small gauge needles enhances irrigation (Figure 16-6). ADDIN EN.CITE Abou-Rass1982101571015717Abou-Rass, M.Piccinino, M. V.The effectiveness of four clinical irrigation methods on the removal of root canal debrisOral Surg Oral Med Oral PatholOral Surg Oral Med Oral Pathol323-8543Comparative StudyDental Pulp Cavity/anatomy & histologyEvaluation StudiesHumansHydrogen Peroxide/administration & dosageIrrigation/ methodsRoot Canal Therapy/instrumentation/ methodsSodium Hypochlorite/administration & dosageSolutions1982Sep0030-4220 (Print)695782882 Unfortunately the small bore can easily clog, so aspiration after each use is recommended. During rinsing, the needle is moved up and down constantly to produce agitation and prevent binding or wedging of the needle. Chlorhexidine Chlorhexidine possesses a broad spectrum of antimicrobial activity, provides a sustained action ADDIN EN.CITE Rosenthal2004101671016717Rosenthal, S.Spangberg, L.Safavi, K.Department of Endodontology, University of Connecticut School of Dental Medicine, Farmington, USA.Chlorhexidine substantivity in root canal dentinOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod488-92984AnimalsAnti-Infective Agents, Local/analysis/ pharmacologyCattleChlorhexidine/analysis/ pharmacologyDental Pulp Cavity/drug effectsDentin/ chemistryEnterococcus faecalis/drug effectsMicrobial Sensitivity TestsSpectrophotometryTime Factors2004Oct1079-2104 (Print)15472666Oncag20031044104417Oncag, O.Hosgor, M.Hilmioglu, S.Zekioglu, O.Eronat, C.Burhanoglu, D.Department of Pedodontics, Dental Faculty, Ege University, Bornova, Izmir, Turkey. oncag@egenet.com.trComparison of antibacterial and toxic effects of various root canal irrigantsInternational Endodontic JournalInternational Endodontic Journal423-323662003Jun1280129081, 83, and has little toxicity. ADDIN EN.CITE Jeansonne19949856985617Jeansonne, M. J.White, R. R.Dental Branch, University of Texas Health Science Center, Houston.A comparison of 2.0% chlorhexidine gluconate and 5.25% sodium hypochlorite as antimicrobial endodontic irrigantsJ EndodJ Endod276-8206Analysis of VarianceBacteria, Anaerobic/drug effects/growth & developmentChi-Square DistributionChlorhexidine/ analogs & derivatives/pharmacologyColony Count, MicrobialComparative StudyHumansRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacologyStatistics, Nonparametric1994Jun0099-2399 (Print)7931023Vahdaty19939859985917Vahdaty, A.Pitt Ford, T. R.Wilson, R. F.Department of Conservative Dental Surgery, Guy's Hospital, London, England.Efficacy of chlorhexidine in disinfecting dentinal tubules in vitroEndod Dent TraumatolEndod Dent Traumatol243-896Analysis of VarianceAnimalsCattleChlorhexidine/ pharmacologyComparative StudyDental Pulp Cavity/microbiologyDentin/ microbiologyDisinfection/methodsEnterococcus faecalis/ drug effectsGram-Positive Bacterial Infections/drug therapyMicrobial Sensitivity TestsRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacology1993Dec0109-2502 (Print)8143575Kuruvilla19989860986017Kuruvilla, J. R.Kamath, M. P.Department of Conservative Dentistry and Endodontics, College of Dental Surgery, Mangalore, India.Antimicrobial activity of 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate separately and combined, as endodontic irrigantsJ EndodJ Endod472-6247Anti-Infective Agents, Local/ pharmacologyBacteria/ drug effects/isolation & purificationChlorhexidine/ analogs & derivativesColony Count, MicrobialDental Pulp Cavity/ microbiologyDrug CombinationsDrug SynergismRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacologyStatistics, NonparametricTooth, Nonvital1998Jul0099-2399 (Print)9693573White1997100111001117White, R. R.Hays, G. L.Janer, L. R.Department of Basic Sciences, University of Texas, Houston Health Science Center 77225, USA.Residual antimicrobial activity after canal irrigation with chlorhexidineJ EndodJ Endod229-31234Analysis of VarianceAnti-Infective Agents, Local/ pharmacologyChlorhexidine/ pharmacologyDental Pulp Cavity/ microbiologyHumansMicrobial Sensitivity TestsResearch Support, Non-U.S. Gov'tRoot Canal Irrigants/ pharmacologyStreptococcus mutans/drug effects/growth & development1997Apr0099-2399 (Print)959477184-87 Two percent chlorhexadine has similar antimicrobial action as 5.25% sodium hypochlorite ADDIN EN.CITE Jeansonne19949856985617Jeansonne, M. J.White, R. R.Dental Branch, University of Texas Health Science Center, Houston.A comparison of 2.0% chlorhexidine gluconate and 5.25% sodium hypochlorite as antimicrobial endodontic irrigantsJ EndodJ Endod276-8206Analysis of VarianceBacteria, Anaerobic/drug effects/growth & developmentChi-Square DistributionChlorhexidine/ analogs & derivatives/pharmacologyColony Count, MicrobialComparative StudyHumansRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacologyStatistics, Nonparametric1994Jun0099-2399 (Print)793102384 and is more effective against enterococcus faecalis. ADDIN EN.CITE Oncag20031044104417Oncag, O.Hosgor, M.Hilmioglu, S.Zekioglu, O.Eronat, C.Burhanoglu, D.Department of Pedodontics, Dental Faculty, Ege University, Bornova, Izmir, Turkey. oncag@egenet.com.trComparison of antibacterial and toxic effects of various root canal irrigantsInternational Endodontic JournalInternational Endodontic Journal423-323662003Jun1280129081 Sodium hypochlorite and chlorhexadine are synergistic in their ability to eliminate microorganisms.  ADDIN EN.CITE Kuruvilla19989860986017Kuruvilla, J. R.Kamath, M. P.Department of Conservative Dentistry and Endodontics, College of Dental Surgery, Mangalore, India.Antimicrobial activity of 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate separately and combined, as endodontic irrigantsJ EndodJ Endod472-6247Anti-Infective Agents, Local/ pharmacologyBacteria/ drug effects/isolation & purificationChlorhexidine/ analogs & derivativesColony Count, MicrobialDental Pulp Cavity/ microbiologyDrug CombinationsDrug SynergismRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacologyStatistics, NonparametricTooth, Nonvital1998Jul0099-2399 (Print)969357385 A disadvantage of chlorhexadine is its inability to dissolve necrotic tissue and remove the smear layer. LUBRICANTS Lubricants facilitate file manipulation during cleaning and shaping. They are an aid in initial canal negotiation especially in small constricted canals without taper. They reduce torsional forces on the instruments and decrease the potential for fracture. Glycerin is a mild alcohol that is inexpensive, nontoxic, aseptic, and somewhat soluble. A small amount can be placed along the shaft of the file or deposited in the canal orifice. Counterclockwise rotation of the file carries the material apically. The file can then be worked to place using a watch winding or twiddling motion. Paste lubricants can incorporate chelators. One advantage to paste lubricants is that they can suspend dentinal debris and prevent apical compaction. One proprietary product consists of glycol, urea peroxide and ethylenediaminetetraacetic acid (EDTA) in a special water soluble base. It has been demonstrated to exhibit an antimicrobial action ADDIN EN.CITE Steinberg1999101601016017Steinberg, D.Abid-el-Raziq, D.Heling, I.Department of Oral Biology, Faculty of Dental Medicine, Hebrew University-Hadassah, Jerusalem, Israel.In vitro antibacterial effect of RC-Prep components on Streptococcus sobrinusEndod Dent TraumatolEndod Dent Traumatol171-4154Anti-Infective Agents, Local/ pharmacologyColony Count, MicrobialComparative StudyDrug CombinationsDrug InteractionsEdetic Acid/chemistry/ pharmacologyGlycols/pharmacologyMicrobial Sensitivity TestsPeroxides/chemistry/ pharmacologyRoot Canal Irrigants/chemistry/ pharmacologyStreptococcus sobrinus/ drug effectsUrea/analogs & derivatives/chemistry/ pharmacologyWaxes/chemistry/ pharmacology1999Aug0109-2502 (Print)1081556688. Another type is composed of 19% EDTA in a water soluble viscous solution. A disadvantage to these EDTA compounds appears to be the deactivation of sodium hypochlorite by reducing the available chlorine ADDIN EN.CITE Zehnder20059831983117Zehnder, M.Schmidlin, P.Sener, B.Waltimo, T.Department of Preventive Dentistry, Cariology, and Periodontology, Division of Endodontics, University of Zurich Center for Dental Medicine, Zurich, Switzerland. matthias.zehnder@zzmk.unizh.chChelation in root canal therapy reconsideredJ EndodJ Endod817-203111Anti-Infective Agents, Local/chemistry/therapeutic useCalcium/chemistryChelating Agents/ therapeutic useChlorine/chemistryCitric Acid/chemistry/therapeutic useDental Pulp Cavity/drug effects/ultrastructureEdetic Acid/chemistry/therapeutic useEnterococcus faecalis/drug effectsEtidronic Acid/chemistry/therapeutic useHumansMicroscopy, Electron, ScanningOrganophosphorus Compounds/chemistry/therapeutic usePolyphosphates/chemistry/therapeutic useRoot Canal Irrigants/ therapeutic useRoot Canal TherapySmear LayerSodium Hypochlorite/chemistry/therapeutic useSpectrophotometry, Atomic2005Nov0099-2399 (Print)1624972689 and potential toxicity ADDIN EN.CITE Cehreli2002101611016117Cehreli, Z. C.Onur, M. A.Tasman, F.Gumrukcuoglu, A.Artuner, H.Department of Pedodontics, Faculty of Dentistry, Hacettepe University, Ankara, Turkey.Effects of current and potential dental etchants on nerve compound action potentialsJ EndodJ Endod149-51283Acid Etching, Dental/ adverse effectsAction Potentials/ drug effectsAnimalsChelating Agents/toxicityComparative StudyEdetic Acid/toxicityFemaleMaleates/ toxicityNeural ConductionOrganic ChemicalsPeroxides/toxicityPhosphonic Acids/ toxicityRatsSciatic Nerve/ drug effectsStatistics, NonparametricUrea/toxicityWaxes/toxicity2002Mar0099-2399 (Print)1201716890. The addition of EDTA to the lubricants has not proven to be effective ADDIN EN.CITE Goldberg19777617761717Goldberg, F.Abramovich, A.Analysis of the effect of EDTAC on the dentinal walls of the root canalJournal of EndodonticsJournal of Endodontics101-5331977Mar40438091. In general files remove dentin faster than the chelators can soften the canal walls. Aqueous solutions such as sodium hypochlorite should be used instead of paste lubricants when using nickel-titanium rotary techniques to reduce torque ADDIN EN.CITE Peters20059794979417Peters, O. A.Boessler, C.Zehnder, M.Division of Endodontology, Department of Preventive Dentistry, Periodontology, and Cariology, University of Zurich Center for Dental Medicine, Zurich, Switzerland.Effect of liquid and paste-type lubricants on torque values during simulated rotary root canal instrumentationInt Endod JInt Endod J223-9384Analysis of VarianceComparative StudyDental InstrumentsDental Stress AnalysisEdetic AcidHumansLubricationMaterials TestingMolarRoot Canal IrrigantsRoot Canal Preparation/ instrumentationTorque2005Apr0143-2885 (Print)1581097276. SMEAR LAYER During the cleaning and shaping, organic pulpal materials and inorganic dentinal debris accummulates on the radicular canal wall producing a an amorphous irregular smear layer (Figure 16-8). ADDIN EN.CITE Torabinejad20021179117917Torabinejad, M.Handysides, R.Khademi, A. A.Bakland, L. K.Department of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.Clinical implications of the smear layer in endodontics: a reviewOral Surgery Oral Medicine Oral Pathology Oral Radiology & EndodonticsOral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics658-669462002Dec1246488769 With pulp necrosis, the smear layer may be contaminated with bacteria and their metabolic by-products. The smear layer is superficial with a thickness of 1-5 microns and debris can be packed into the dentinal tubules varying distances. ADDIN EN.CITE McComb19757888788817McComb, D.Smith, D. C.A preliminary scanning electron microscopic study of root canals after endodontic proceduresJournal of EndodonticsJournal of Endodontics238-42171975Jul1061799McComb19757888788817McComb, D.Smith, D. C.A preliminary scanning electron microscopic study of root canals after endodontic proceduresJournal of EndodonticsJournal of Endodontics238-42171975Jul106179992 There does not appear to be a consensus on removing the smear layer prior to obturation.  ADDIN EN.CITE Chailertvanitkul1996101231012317Chailertvanitkul, P.Saunders, W. P.MacKenzie, D.University of Glasgow Dental School, UK.The effect of smear layer on microbial coronal leakage of gutta-percha root fillingsInt Endod JInt Endod J242-8294Calcium HydroxideChi-Square DistributionComparative StudyDental LeakageDental Pulp Cavity/microbiologyEvaluation StudiesGutta-PerchaHumansRoot Canal Filling MaterialsRoot Canal Obturation/methodsRoot Canal PreparationSmear LayerStatistics, NonparametricStreptococcus sanguis/isolation & purificationTooth Crown/microbiology1996Jul0143-2885 (Print)9206440Sen19952873287317Sen, B. H.Wesselink, P. R.Turkun, M.Department of Endodontics, Ege University, Izmir, Turkey.The smear layer: a phenomenon in root canal therapyInternational Endodontic JournalInternational Endodontic Journal141-82831995May8626198Torabinejad20021179117917Torabinejad, M.Handysides, R.Khademi, A. A.Bakland, L. K.Department of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.Clinical implications of the smear layer in endodontics: a reviewOral Surgery Oral Medicine Oral Pathology Oral Radiology & EndodonticsOral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics658-669462002Dec1246488793, 94, 69 The advantages and disadvantages of the smear layer removal remain controversial; however, evidence supports removing the smear layer prior to obturation. ADDIN EN.CITE Clark-Holke20031076107617Clark-Holke, D.Drake, D.Walton, R.Rivera, E.Guthmiller, J. M.College of Dentistry, Dows Institute of Dental Research, University of Iowa, 801 Newton Road, Iowa City, IA 52242, USA.Bacterial penetration through canals of endodontically treated teeth in the presence or absence of the smear layerJournal of DentistryJournal of Dentistry275-813142003May12735922Torabinejad20021179117917Torabinejad, M.Handysides, R.Khademi, A. A.Bakland, L. K.Department of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.Clinical implications of the smear layer in endodontics: a reviewOral Surgery Oral Medicine Oral Pathology Oral Radiology & EndodonticsOral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics658-669462002Dec1246488795, 69 The organic debris present in the smear layer might constitute substrate for bacterial growth and it has been suggested that the smear layer prohibits sealer contact with the canal wall and permits leakage. In addition, viable microorganisms in the dentinal tubules may use the smear layer as a substrate for sustained growth. When the smear layer is not removed, it may slowly disintegrate with leaking obturation materials, or it may be removed by acids and enzymes that are produced by viable bacteria left in the tubules or enter via coronal leakage.  ADDIN EN.CITE Delivanis19835969596917Delivanis, P. D.Mattison, G. D.Mendel, R. W.The survivability of F43 strain of Streptococcus sanguis in root canals filled with gutta-percha and Procosol cementJournal of EndodonticsJournal of Endodontics407-109101983Oct657916496 The presence of a smear layer may also interfere with the action and effectiveness of root canal irrigants and inter-appointment disinfectants. ADDIN EN.CITE Orstavik19909762976217Orstavik, D.Haapasalo, M.Scandinavian Institute of Dental Materials, Oslo.Disinfection by endodontic irrigants and dressings of experimentally infected dentinal tubulesEndod Dent TraumatolEndod Dent Traumatol142-964AnimalsBacteria/growth & developmentBacterial Infections/ drug therapyCattleDental Pulp Diseases/ drug therapyDentin/ ultrastructureMicroscopy, Electron, ScanningRoot Canal Irrigants/ therapeutic useSmear Layer1990Aug0109-2502 (Print)213330537 With smear layer removal filling materials adapt better to the canal wall. ADDIN EN.CITE Oksan1993101331013317Oksan, T.Aktener, B. O.Sen, B. H.Tezel, H.Department of Endodontics, Ege University Dental Faculty, Bornova, Izmir, Turkey.The penetration of root canal sealers into dentinal tubules. A scanning electron microscopic studyInt Endod JInt Endod J301-5265Analysis of VarianceBismuth/pharmacokineticsComparative StudyDentin/ ultrastructureDentin PermeabilityDrug CombinationsEugenol/pharmacokineticsFormaldehyde/pharmacokineticsHumansMicroscopy, Electron, ScanningPolymers/pharmacokineticsPolyvinyls/pharmacokineticsResorcinols/pharmacokineticsRoot Canal Filling Materials/ pharmacokineticsSmear LayerZinc Oxide/pharmacokinetics1993Sep0143-2885 (Print)8300262Wennberg1990101321013217Wennberg, A.Orstavik, D.Scandinavian Institute of Dental Materials, Haslum, Norway.Adhesion of root canal sealers to bovine dentine and gutta-perchaInt Endod JInt Endod J13-9231AdhesivenessAnimalsCattleComparative StudyDental BondingDentin/drug effects/ ultrastructureEdetic Acid/pharmacologyGutta-PerchaMaterials TestingRoot Canal Filling MaterialsSurface PropertiesTensile Strength1990Jan0143-2885 (Print)211812497, 98 Removal of the smear layer also enhances the adhesion of sealers to dentin and tubular penetration ADDIN EN.CITE Wennberg1990101321013217Wennberg, A.Orstavik, D.Scandinavian Institute of Dental Materials, Haslum, Norway.Adhesion of root canal sealers to bovine dentine and gutta-perchaInt Endod JInt Endod J13-9231AdhesivenessAnimalsCattleComparative StudyDental BondingDentin/drug effects/ ultrastructureEdetic Acid/pharmacologyGutta-PerchaMaterials TestingRoot Canal Filling MaterialsSurface PropertiesTensile Strength1990Jan0143-2885 (Print)2118124Oksan1993101331013317Oksan, T.Aktener, B. O.Sen, B. H.Tezel, H.Department of Endodontics, Ege University Dental Faculty, Bornova, Izmir, Turkey.The penetration of root canal sealers into dentinal tubules. A scanning electron microscopic studyInt Endod JInt Endod J301-5265Analysis of VarianceBismuth/pharmacokineticsComparative StudyDentin/ ultrastructureDentin PermeabilityDrug CombinationsEugenol/pharmacokineticsFormaldehyde/pharmacokineticsHumansMicroscopy, Electron, ScanningPolymers/pharmacokineticsPolyvinyls/pharmacokineticsResorcinols/pharmacokineticsRoot Canal Filling Materials/ pharmacokineticsSmear LayerZinc Oxide/pharmacokinetics1993Sep0143-2885 (Print)8300262Leonard1996101311013117Leonard, J. E.Gutmann, J. L.Guo, I. Y.Department of Restorative Sciences, Baylor College of Dentistry, Dallas, Texas 75246, USA.Apical and coronal seal of roots obturated with a dentine bonding agent and resinInt Endod JInt Endod J76-83292Boron CompoundsComparative StudyDental LeakageDentin/ultrastructureDentin-Bonding AgentsGlass Ionomer CementsGutta-PerchaHumansMethacrylatesMethylmethacrylatesMicroscopy, Electron, ScanningResin CementsRoot Canal Filling MaterialsRoot Canal Obturation/ methodsStatistics, Nonparametric1996Mar0143-2885 (Print)9206428Sen1996101341013417Sen, B. H.Piskin, B.Baran, N.Department of Endodontics, School of Dentistry, Ege University, Izmir, Turkey.The effect of tubular penetration of root canal sealers on dye microleakageInt Endod JInt Endod J23-8291Administration, TopicalAnalysis of VarianceAnti-Inflammatory AgentsBismuthCalcium HydroxideComparative StudyDental LeakageDentin/ultrastructureDentin PermeabilityDexamethasoneDrug CombinationsFormaldehydeGlass Ionomer CementsHumansHydrocortisoneMicroscopy, Electron, ScanningPolyvinylsRoot Canal Filling MaterialsStatistics, NonparametricThymol/analogs & derivativesZinc Oxide1996Jan0143-2885 (Print)920640899, 97, 100, 98 and permits the penetration of all sealers to varying depths. ADDIN EN.CITE Kokkas2004101361013617Kokkas, A. B.Boutsioukis, AChVassiliadis, L. P.Stavrianos, C. K.Department of Endodontology, School of Dentistry, Aristotle University, Thessaloniki, Greece.The influence of the smear layer on dentinal tubule penetration depth by three different root canal sealers: an in vitro studyJ EndodJ Endod100-2302Analysis of VarianceCalcium Hydroxide/chemistryChelating Agents/therapeutic useDentin/drug effects/ ultrastructureEdetic Acid/therapeutic useEpoxy Resins/chemistryGutta-Percha/chemistryHumansMaterials TestingMicroscopy, Electron, ScanningRoot Canal Filling Materials/ chemistryRoot Canal Irrigants/therapeutic useRoot Canal Preparation/methodsSmear LayerSodium Hypochlorite/therapeutic useSurface PropertiesZinc Oxide-Eugenol Cement/chemistry2004Feb0099-2399 (Print)14977306101 Removal of the smear layer reduces both coronal and apical leakage. ADDIN EN.CITE Cobankara2004101381013817Cobankara, F. K.Adanr, N.Belli, S.Department of Endodontics, Faculty of Dentistry, Selcuk University, Campus 42075, Konya, Turkey. kfunda@selcuk.edu.trEvaluation of the influence of smear layer on the apical and coronal sealing ability of two sealersJ EndodJ Endod406-9306Bismuth/chemistryDental BondingDental Cements/chemistryDental Leakage/ classificationDental Pulp Cavity/ultrastructureDiffusion Chambers, CultureDrug CombinationsEpoxy Resins/chemistryGutta-Percha/chemistryHumansMaterials TestingRoot Canal Filling Materials/ chemistryRoot Canal ObturationRoot Canal PreparationSilver/chemistrySmear LayerTitanium/chemistryTooth ApexTooth Crown2004Jun0099-2399 (Print)15167467102  ADDIN EN.CITE Clark-Holke2003101391013917Clark-Holke, D.Drake, D.Walton, R.Rivera, E.Guthmiller, J. M.College of Dentistry, Dows Institute of Dental Research, University of Iowa, 801 Newton Road, Iowa City, IA 52242, USA.Bacterial penetration through canals of endodontically treated teeth in the presence or absence of the smear layerJ DentJ Dent275-81314Bismuth/therapeutic useCampylobacter/physiologyChelating Agents/therapeutic useColony Count, MicrobialDental Leakage/ microbiology/prevention & controlDental Pulp Cavity/ microbiologyDrug CombinationsEdetic Acid/therapeutic useEpoxy Resins/therapeutic useFusobacterium nucleatum/physiologyGutta-Percha/therapeutic useHumansPeptostreptococcus/physiologyRoot Canal Filling Materials/therapeutic useRoot Canal Irrigants/therapeutic useRoot Canal PreparationRoot Canal TherapySilver/therapeutic useSmear LayerTime FactorsTitanium/therapeutic useTooth Apex/microbiologyTooth, Nonvital/ microbiology2003May0300-5712 (Print)12735922103 EDTA Removal of the smear layer is accomplished with acids or other chelating agents such as ethylenediamine tetracetic acid (EDTA)  ADDIN EN.CITE Hulsmann2003101271012717Hulsmann, M.Heckendorff, M.Lennon, A.Department of Operative Dentistry, Preventive Dentistry and Periodontology, University of Gottingen, Gottingen, Germany. huelsmann@med.uni-goettingen.deChelating agents in root canal treatment: mode of action and indications for their useInt Endod JInt Endod J810-303612Anti-Infective Agents/pharmacologyChelating Agents/chemistry/pharmacologyDentin/drug effectsDentin PermeabilityDentin SolubilityEdetic Acid/chemistry/pharmacologyHumansRoot Canal Irrigants/chemistry/pharmacologyRoot Canal Preparation/methodsSmear Layer2003Dec0143-2885 (Print)14641420104 following cleaning and shaping. Irrigation with 17% EDTA for one minute followed by a final rinse with sodium hypochlorite ADDIN EN.CITE Baumgartner19874881488117Baumgartner, J. C.Mader, C. L.A scanning electron microscopic evaluation of four root canal irrigation regimensJournal of EndodonticsJournal of Endodontics147-571341987Apr3106553105 is a recommended method. Chelators remove the inorganic components leaving the organic tissue elements intact. Sodium hypochlorite is then necessary for removal of the remaining organic components. Citric acid has also been shown to be an effective method for removing the smear layer ADDIN EN.CITE Haznedaroglu2003101421014217Haznedaroglu, F.Istanbul University, Istanbul, Turkey.Efficacy of various concentrations of citric acid at different pH values for smear layer removalOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod340-4963BuffersCitric Acid/ administration & dosage/therapeutic useComparative StudyDental Pulp Cavity/ drug effects/ultrastructureDentin/ drug effects/ultrastructureDisinfectants/therapeutic useHumansHydrogen-Ion ConcentrationMatched-Pair AnalysisMicroscopy, Electron, ScanningRoot Canal Irrigants/ therapeutic useSmear LayerSodium Hypochlorite/therapeutic useStatistics, Nonparametric2003Sep1079-2104 (Print)12973291Baumgartner1984101401014017Baumgartner, J. C.Brown, C. M.Mader, C. L.Peters, D. D.Shulman, J. D.A scanning electron microscopic evaluation of root canal debridement using saline, sodium hypochlorite, and citric acidJ EndodJ Endod525-311011CitratesCitric AcidDental Pulp Cavity/drug effects/ ultrastructureEvaluation StudiesHumansMicroscopy, Electron, ScanningRoot Canal Irrigants/administration & dosage/ pharmacologyRoot Canal Therapy/methodsSodium ChlorideSodium Hypochlorite1984Nov0099-2399 (Print)6594419106, 107 as has tetracycline.  ADDIN EN.CITE Barkhordar19972529252917Barkhordar, R. A.Watanabe, L. G.Marshall, G. W.Hussain, M. Z.Department of Restorative Dentistry, School of Dentistry, University of California, San Francisco, USA.Removal of intracanal smear by doxycycline in vitroOral Surgery Oral Medicine Oral Pathology Oral Radiology & EndodonticsOral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics420-38441997Oct9347508Haznedaroglu2001101431014317Haznedaroglu, F.Ersev, H.Department of Endodontics, Faculty of Dentistry, Istanbul University, Turkey.Tetracycline HCl solution as a root canal irrigantJ EndodJ Endod738-402712Anti-Bacterial Agents/ pharmacologyCitric Acid/pharmacologyComparative StudyCuspidDentin Permeability/ drug effectsHumansMicroscopy, Electron, ScanningRoot Canal Irrigants/ pharmacologySmear LayerSodium Hypochlorite/pharmacologyStatistics, NonparametricSurface Properties/drug effectsTetracycline/ pharmacology2001Dec0099-2399 (Print)11771579108, 109 Demineralization results in removal of the smear layer and plugs, and enlargement of the tubules. ADDIN EN.CITE Guignes19962730273017Guignes, P.Faure, J.Maurette, A.Department of Restorative Dentistry and Endodontics, Faculty of Dental Surgery, Toulouse, France.Relationship between endodontic preparations and human dentin permeability measured in situJournal of EndodonticsJournal of Endodontics60-72221996Feb8935019110  ADDIN EN.CITE Hottel1999101541015417Hottel, T. L.el-Refai, N. Y.Jones, J. J.Department of Restorative Dentistry, Nova Southeastern University, College of Dental Medicine, Ft. Lauderdale, FL 33328, USA.A comparison of the effects of three chelating agents on the root canals of extracted human teethJ EndodJ Endod716-72511Chelating Agents/ pharmacologyComparative StudyDental Pulp Cavity/ drug effectsDentin/drug effectsDentin Permeability/drug effectsEdetic Acid/pharmacologyHumansResearch Support, Non-U.S. Gov'tSmear LayerSuccimer/pharmacologyTriethylenetetramine/pharmacology1999Nov0099-2399 (Print)10726535111 The action is most effective in the coronal and middle thirds of the canal and reduced apically. ADDIN EN.CITE Hulsmann2003101271012717Hulsmann, M.Heckendorff, M.Lennon, A.Department of Operative Dentistry, Preventive Dentistry and Periodontology, University of Gottingen, Gottingen, Germany. huelsmann@med.uni-goettingen.deChelating agents in root canal treatment: mode of action and indications for their useInt Endod JInt Endod J810-303612Anti-Infective Agents/pharmacologyChelating Agents/chemistry/pharmacologyDentin/drug effectsDentin PermeabilityDentin SolubilityEdetic Acid/chemistry/pharmacologyHumansRoot Canal Irrigants/chemistry/pharmacologyRoot Canal Preparation/methodsSmear Layer2003Dec0143-2885 (Print)14641420Lim20031069106917Lim, T. S.Wee, T. Y.Choi, M. Y.Koh, W. C.Sae-Lim, V.Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.Light and scanning electron microscopic evaluation of Glyde File Prep in smear layer removalInternational Endodontic JournalInternational Endodontic Journal336-433652003May12752647104, 112 Reduced activity may be a reflection of canal size ADDIN EN.CITE Krell19884608460817Krell, K. V.Johnson, R. J.Madison, S.Irrigation patterns during ultrasonic canal instrumentation. Part I. K-type filesJournal of EndodonticsJournal of Endodontics65-81421988Feb316294162 or anatomical variations such as irregular or sclerotic tubules. ADDIN EN.CITE Mjor2001101551015517Mjor, I. A.Smith, M. R.Ferrari, M.Mannocci, F.College of Dentistry, University of Florida, Gainesville 32610, USA. imjor@dental.ufl.eduThe structure of dentine in the apical region of human teethInt Endod JInt Endod J346-53345AdultAgedDentin/ anatomy & histology/ultrastructureDentin PermeabilityDentin, Secondary/anatomy & histologyHumansMicroscopy, ConfocalMiddle AgedTooth Apex/ anatomy & histology2001Jul0143-2885 (Print)11482717113 The variable structure of the apical region presents a challenge during endodontic obturation with adhesive materials. The recommended time for removal of the smear layer with EDTA is 1 minute. ADDIN EN.CITE alt20003315ChapterNine-Converted.enlEndNote331517<style face='normal' font='default' size='100%'>Smear layer removal by EGTA</style>Hulsmann2003101271012717Hulsmann, M.Heckendorff, M.Lennon, A.Department of Operative Dentistry, Preventive Dentistry and Periodontology, University of Gottingen, Gottingen, Germany. huelsmann@med.uni-goettingen.deChelating agents in root canal treatment: mode of action and indications for their useInt Endod JInt Endod J810-303612Anti-Infective Agents/pharmacologyChelating Agents/chemistry/pharmacologyDentin/drug effectsDentin PermeabilityDentin SolubilityEdetic Acid/chemistry/pharmacologyHumansRoot Canal Irrigants/chemistry/pharmacologyRoot Canal Preparation/methodsSmear Layer2003Dec0143-2885 (Print)14641420Scelza20031130113017Scelza, M. F.Teixeira, A. M.Scelza, P.Department of Endodontics, Federal University Fluminense, RJ, Brazil.Decalcifying effect of EDTA-T, 10% citric acid, and 17% EDTA on root canal dentinOral Surgery Oral Medicine Oral Pathology Oral Radiology & EndodonticsOral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics234-69522003Feb12582366114, 104, 115 The small particles of the smear layer are primarily inorganic with a high surface to mass ratio which facilitates removal by acids and chelators. EDTA exposure over 10 minutes causes excessive removal of both peritubular and intratubular dentin. ADDIN EN.CITE Calt20001778177817Calt, S.Serper, A.Department of Endodontics, Hacettepe University, Faculty of Dentistry, Sihhiye (06100) Ankara, Turkey.Smear layer removal by EGTAJournal of EndodonticsJournal of Endodontics459-612682000Aug11199779116 MTAD An alternative method for removing the smear layer employs the use of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) as a final rise to remove the smear layer. ADDIN EN.CITE Torabinejad2003101461014617Torabinejad, M.Khademi, A. A.Babagoli, J.Cho, Y.Johnson, W. B.Bozhilov, K.Kim, J.Shabahang, S.Department of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.A new solution for the removal of the smear layerJ EndodJ Endod170-5293Chelating Agents/chemistry/therapeutic useCitric Acid/chemistry/therapeutic useComparative StudyDental AlloysDental Pulp Cavity/ drug effects/ultrastructureDentin/ drug effects/ultrastructureDetergents/chemistry/therapeutic useDoxycycline/chemistry/therapeutic useEdetic Acid/therapeutic useHumansMicroscopy, Electron, ScanningNickelPolysorbates/chemistry/therapeutic useRoot Canal Irrigants/chemistry/ therapeutic useRoot Canal Preparation/instrumentation/methodsSmear LayerSodium Hypochlorite/therapeutic useStatisticsTitaniumWater2003Mar0099-2399 (Print)12669874117 The effectiveness of MTAD to completely remove the smear layer is enhanced when low concentrations of NaOCl are used as an intracanal irrigant before the use of MTAD ADDIN EN.CITE Torabinejad2003101531015317Torabinejad, M.Cho, Y.Khademi, A. A.Bakland, L. K.Shabahang, S.Endodontic Residency Program, School of Dentistry, Loma Linda University, CA 92350, USA.The effect of various concentrations of sodium hypochlorite on the ability of MTAD to remove the smear layerJ EndodJ Endod233-9294Anti-Bacterial AgentsChelating AgentsChi-Square DistributionCitric AcidDentin/ultrastructureDetergentsDoxycyclineDrug CombinationsEdetic AcidHumansMicroscopy, Electron, ScanningOdds RatioPolysorbatesRoot Canal IrrigantsSmear LayerSodium Hypochlorite/administration & dosage2003Apr0099-2399 (Print)12701769118. A 1.3% concentration is recommended. MTAD may be superior to sodium hypochlorite in antimicrobial action. ADDIN EN.CITE Shabahang2003101521015217Shabahang, S.Pouresmail, M.Torabinejad, M.Loma Linda University, CA, USA.In vitro antimicrobial efficacy of MTAD and sodium hypochloriteJ EndodJ Endod450-2297Bacteria/drug effectsCitric Acid/ pharmacologyComparative StudyDetergents/pharmacologyDoxycycline/ pharmacologyHumansNephelometry and TurbidimetryPolysorbates/ pharmacologyRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacology2003Jul0099-2399 (Print)12877261Shabahang2003101511015117Shabahang, S.Torabinejad, M.Dept. of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.Effect of MTAD on Enterococcus faecalis-contaminated root canals of extracted human teethJ EndodJ Endod576-9299Anti-Bacterial Agents/therapeutic useChelating Agents/therapeutic useChi-Square DistributionCitric Acid/ therapeutic useComparative StudyDental Pulp Cavity/ microbiologyDentin/microbiologyDisinfectants/therapeutic useDoxycycline/ therapeutic useEdetic Acid/therapeutic useEnterococcus faecalis/ drug effectsGram-Positive Bacterial Infections/microbiology/ therapyHumansPolysorbates/ therapeutic useRoot Canal Irrigants/ therapeutic useRoot Canal PreparationSingle-Blind MethodSodium Hypochlorite/therapeutic useSurface-Active Agents/therapeutic use2003Sep0099-2399 (Print)14503830119, 120 MTAD has been shown to be effective in killing E. faecalis, an organism commonly found in failing cases, and may prove beneficial during retreatment. It is biocompatible ADDIN EN.CITE Zhang2003103391033917Zhang, W.Torabinejad, M.Li, Y.Center for Dental Research, Loma Linda University, CA 92350, USA.Evaluation of cytotoxicity of MTAD using the MTT-tetrazolium methodJ EndodJ Endod654-72910AnimalsCalcium Hydroxide/toxicityCell Division/drug effectsCetrimonium Compounds/toxicityChlorhexidine/ analogs & derivatives/toxicityCitric Acid/ toxicityColoring AgentsComparative StudyDoxycycline/ toxicityEdetic Acid/toxicityL Cells (Cell Line)/drug effectsMicePolysorbates/ toxicityRoot Canal Irrigants/ toxicitySmear LayerSodium Hypochlorite/toxicityTetrazolium SaltsThiazoles2003Oct0099-2399 (Print)14606789121, does not alter the physical properties of the dentin ADDIN EN.CITE Zhang2003103391033917Zhang, W.Torabinejad, M.Li, Y.Center for Dental Research, Loma Linda University, CA 92350, USA.Evaluation of cytotoxicity of MTAD using the MTT-tetrazolium methodJ EndodJ Endod654-72910AnimalsCalcium Hydroxide/toxicityCell Division/drug effectsCetrimonium Compounds/toxicityChlorhexidine/ analogs & derivatives/toxicityCitric Acid/ toxicityColoring AgentsComparative StudyDoxycycline/ toxicityEdetic Acid/toxicityL Cells (Cell Line)/drug effectsMicePolysorbates/ toxicityRoot Canal Irrigants/ toxicitySmear LayerSodium Hypochlorite/toxicityTetrazolium SaltsThiazoles2003Oct0099-2399 (Print)14606789121 and it enhances bond strength. ADDIN EN.CITE Machnick2003101491014917Machnick, T. K.Torabinejad, M.Munoz, C. A.Shabahang, S.Department of Endodontics, School of Dentistry, Loma Linda University, CA 92350, USA.Effect of MTAD on the bond strength to enamel and dentinJ EndodJ Endod818-212912Analysis of VarianceCitric AcidComparative StudyDental EnamelDental Etching/ methodsDental Stress AnalysisDentinDentin-Bonding AgentsDoxycyclineHumansMaterials TestingPhosphoric AcidsPolysorbatesResin CementsRoot Canal IrrigantsShear StrengthStatistics, Nonparametric2003Dec0099-2399 (Print)14686813122 TECHNIQUES OF PREPARATION Regardless of the technique used in cleaning and shaping, procedural errors can occur. These included loss of working length, apical transportation, apical perforation, lateral stripping and instrument fracture. Loss of working length has several causes. These include failure to have an adequate reference point from which the corrected working length is determined, packing tissue and debris in the apical portion of the canal, ledge formation, and inaccurate measurements. Apical transportation and zipping occurs when the restoring force of the file exceeds the threshold for cutting dentin in cylindrical non-tapering curved canal (Figures 16-9 and 16-10). ADDIN EN.CITE Powell1988102571025717Powell, S. E.Wong, P. D.Simon, J. H.A comparison of the effect of modified and nonmodified instrument tips on apical canal configuration. Part IIJ EndodJ Endod224-8145Comparative StudyDental Pulp Cavity/anatomy & histologyEquipment DesignRoot Canal Therapy/ instrumentation1988May0099-2399 (Print)3251976123 When this apical transportation continues with larger and larger files, a teardrop shape develops and perforation can occur apically on the lateral root surface (Figure16-9). Transportation in curved canals begins with a size #25 file ADDIN EN.CITE Eldeeb19855518551817Eldeeb, M. E.Boraas, J. C.The effect of different files on the preparation shape of severely curved canalsInternational Endodontic JournalInternational Endodontic Journal1-71811985Jan385823415. Enlargement of curved canals at the corrected working length beyond a size #25 file should be done only when an adequate coronal flare is developed. Instrument fracture occurs with torsional and cyclic fatigue. Locking the flutes of a file in the canal wall while continuing to rotate the coronal portion of the instrument is an example torsional fatigue (Figure 16-11). Cyclic fatigue results when strain develops in the metal. Stripping perforations occur in the furcal region of curved roots, frequently the mesial roots of maxillary and mandibular molars perforation (Figures 16-12 and 16-13). The canal in this area is not always centered in the root and prior to preparation the average distance to the furcal wall (danger zone) is less than the distance to the bulky outer wall (safety zone). An additional factor is the concavity of the root. Watch Winding Watch winding is reciprocating back and forth (clockwise/counterclockwise) rotation of the instrument in an arch. It is used to negotiate canals and to work files to place. Light apical pressure is applied to move the file deeper into the canal. Reaming Reaming is defined as the clockwise, cutting rotation of the file. Generally the instruments are placed into the canal until binding is encountered. The instrument is then rotated clockwise 180-360 to plane the walls and enlarge the canal space. Filing Filing is defined as placing the file into the canal and pressing it laterally while withdrawing it along the path of insertion to scrape the wall. There is very little rotation on the outward cutting stroke. The scraping or rasping action removes the tissue and cuts superficial dentin from the canal wall. A modification is the turn-pull technique. This involves placing the file to the point of binding, rotating the instrument 90 and pulling the instrument along the canal wall. Circumferential filing Circumferential filing is used for canals that are larger and or not round. The file is placed into the canal and withdrawn in a directional manner sequentially against the mesial, distal, buccal, and lingual walls. Standardized preparation After 1961, instruments were manufactured with a standard formula. Clinicians utilized a preparation technique of sequentially enlarging the canal space with smaller to larger instruments at the corrected working length. ADDIN EN.CITE Ingle1961103191031917Ingle, J. I.A standardized endodontic technique utilizing newly designed instruments and filling materialsOral Surg Oral Med Oral PatholOral Surg Oral Med Oral Pathol83-9114Root Canal Therapy/ supply & distributionROOT CANAL THERAPY/equipment and supplies1961Jan0030-4220 (Print)13717698124 In theory this created a standardized preparation of uniform taper. Unfortunately this does not occur. This technique was adequate for preparing the apical portion of canals that were relatively straight and tapered; however in cylindrical and small curved canals procedural errors were identified with the technique. ADDIN EN.CITE Weine19757980798017Weine, F. S.Kelly, R. F.Lio, P. J.Loyola University School of Dentistry, Maywood, Ill. 60153, USA.The effect of preparation procedures on original canal shape and on apical foramen shapeJournal of EndodonticsJournal of Endodontics255-62181975Aug10697472125 Step-back Technique The step-back technique ADDIN EN.CITE Weine19757980798017Weine, F. S.Kelly, R. F.Lio, P. J.Loyola University School of Dentistry, Maywood, Ill. 60153, USA.The effect of preparation procedures on original canal shape and on apical foramen shapeJournal of EndodonticsJournal of Endodontics255-62181975Aug10697472Walton19767738773817Walton, R. E.Histologic evaluation of different methods of enlarging the pulp canal spaceJournal of EndodonticsJournal of Endodontics304-112101976Oct106820770, 125 reduces procedural errors and improves debridement. After coronal flaring and determining the master apical file (initial file that binds slightly at the corrected working length), the succeeding larger files are shortened by 0.5 or 1.0 m increments from the previous file length (Figure 16-14 and 16-15). This step-back process creates a flared, tapering preparation while reducing procedural errors. The step-back preparation is superior to standardized serial filing and reaming techniques in debridement and maintaining the canal shape. ADDIN EN.CITE Walton19767738773817Walton, R. E.Histologic evaluation of different methods of enlarging the pulp canal spaceJournal of EndodonticsJournal of Endodontics304-112101976Oct106820770 The step-back filing technique results in more pulpal walls being planed when compared to reaming or filing. Step-Down Technique The step down technique is advocated for cleaning and shaping procedures as it removes coronal interferences and provides coronal taper. Originally advocated for hand file preparation ADDIN EN.CITE Morgan1984102651026517Morgan, L. F.Montgomery, S.An evaluation of the crown-down pressureless techniqueJ EndodJ Endod491-81010HumansPressureRoot Canal Therapy/instrumentation/ methods1984Oct0099-2399 (Print)6593413126 it has been incorporated into techniques employing nickel-titanium files. With the pulp chamber filled with irrigant or lubricant the canal is explored with a small instrument to assess patency and morphology (curvature). The working length can be established at this time. The coronal one third of the canal is then flared with Gates Glidden drills or rotary files of greater taper (.06, .08, .10,). A large file (such size #70) is then placed in the canal using a watch winding motion until resistance is encountered. ADDIN EN.CITE Morgan1984102651026517Morgan, L. F.Montgomery, S.An evaluation of the crown-down pressureless techniqueJ EndodJ Endod491-81010HumansPressureRoot Canal Therapy/instrumentation/ methods1984Oct0099-2399 (Print)6593413126 The process is repeated with sequentially smaller files until the apical portion of the canal is reached. The working length can be determined if this was not accomplished initially. The apical portion of the canal can now be prepared by enlarging the canal at the corrected working length. Apical taper is accomplished using a step-back technique. Passive Step-back The passive step-back technique is a modification of the incremental step-back technique. ADDIN EN.CITE Schilder19748147814717Schilder, H.Cleaning and shaping the root canalDental Clinics of North AmericaDental Clinics of North America269-961821974Apr4522570Torabinejad199415815817Torabinejad, M.Department of Endodontics, Loma Linda University, School of Dentistry, Calif.Passive step-back techniqueOral Surgery, Oral Medicine, Oral PathologyOral Surgery, Oral Medicine, Oral Pathology398-4017741994Apr80158056, 127 After the apical diameter of the canal has been determined, the next higher instrument is inserted until it first makes contact (binding point). It is then rotated one half turn and removed (Figure 16-16). The process is repeated with larger and larger instruments being placed to their binding point. This entire instrument sequence is then repeated. With each sequence the instruments drop deeper into the canal creating a tapered preparation. This technique permits the canal morphology to dictate the preparation shape. The technique does not require arbitrary rigid incremental reductions and forcing files into canals that cannot accommodate the files. Advantages to the technique include: knowledge of canal morphology, removal of debris and minor canal obstructions, and a gradual passive enlargement of the canal in an apical to coronal direction. Box-3 The diameter of rotary flaring instruments. Size Gates-Glidden Peeso-Reamers #1 .5 mm .7 mm #2 .7 mm .9 mm #3 .9 mm 1.1 mm #4 1.1 mm 1.3 mm #5 1.3 mm 1.5 mm #6 1.5 mm 1.7 mm Anti-Curvature Filing Anti-curvature filing is advocated during coronal flaring procedures to preserve the furcal wall in treatment of molars (Figure 16-17). Canals are often not centered in mesial roots of maxillary and mandibular molars, being located closer to the furcation. Stripping perforations can occur in these teeth during overly aggressive enlargement of the canal space. Stripping perforations occur primarily during use of the Gates Glidden drills (Box-3) (Figure 16-18). To prevent this procedural error, the Gates Glidden drills should be confined to the canal space coronal to the root curvature and used in a step-back manner (Figure 16-18 and 16-19). The Gates Glidden drills can also be used directionally in an anti-curvature fashion to selectively remove dentin from the bulky wall (safety zone) toward the line angle, protecting the inner or furcal wall (danger zone) coronal to the curve (Figure 16-17). While this can be accomplished with the use of hand files, it appears that directional forces with Gates Glidden drills is not beneficial. ADDIN EN.CITE Wu20059845984517Wu, M. K.van der Sluis, L. W.Wesselink, P. R.Department of Cariology, Endodontology, and Pedodontology, Academic Centre For Dentistry Amsterdam, Amsterdam, the Netherlands. m.wu@acta.nlThe risk of furcal perforation in mandibular molars using Gates-Glidden drills with anticurvature pressureOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod378-82993Dental Instruments/ adverse effectsDental Pulp Cavity/anatomy & histologyHumansImage Processing, Computer-AssistedMandibleMolarOdontometryPhotography, DentalPressureRoot Canal Preparation/adverse effects/ instrumentationTooth Injuries/etiology/prevention & controlTooth Root/ anatomy & histology/injuries2005Mar1079-2104 (Print)15716849128 Balanced Force Technique The balanced force technique recognizes the fact that instruments are guided by the canal walls when rotated. ADDIN EN.CITE Roane19855502550217Roane, J. B.Sabala, C. L.Duncanson, M. G., Jr.The "balanced force" concept for instrumentation of curved canalsJournal of EndodonticsJournal of Endodontics203-111151985May3858415129 Since the files will cut in both a clockwise and counterclockwise rotation, the balanced force concept of instrumentation consists of placing the file to length and then a clockwise rotation (less than 180 degrees) engages dentin. This is followed by a counterclockwise rotation (at least 120 degrees) with apical pressure to cut and enlarge the canal. The degree of apical pressure varies from light pressure with small instruments to heavy pressure with large instruments. The clockwise rotation pulls the instrument into the canal in an apical direction. The counterclockwise cutting rotation forces the file in a coronal direction while cutting circumferentially. Following the cutting rotation the file is repositioned and the process is repeated until the corrected working length is reached. At this point a final clockwise rotation is employed to evacuate the debris. Nickel Titanium Rotary Preparation Nickel titanium rotary preparation utilizes a crown-down approach. The specific technique is based on the instrument system selected. One instrument sequence uses nickel titanium files with a constant taper and variable ISO tip sizes (Figure 16-20). With this technique, a .06 taper is selected. Initially a size .06/45 file is used until resistance, followed by the .06/45, .06/40, .06/35, .06/30, .06/25, and .06/20. In a second technique, nickel titanium files with a constant tip diameter are used. The initial file is a .10/20 instrument, the second a .08/20, the third a .06/20, and the fourth a .04/20 (Figure 16-21). For larger canals a sequence of files using ISO standardized tip sizes of 30 or 40 might be selected. Using the crown down approach creates coronal flare and reduces the contact area of the file so torsional forces are reduced. Final Apical Enlargement and Apical Clearing Apical clearing enhances the preparation of the apical canal, improves debridement, and produce a more definite apical stop in preparation for obturation. ADDIN EN.CITE Parris19943141314117Parris, J.Wilcox, L.Walton, R.Department of Endodontics, University of Iowa, College of Dentistry.Effectiveness of apical clearing: histological and radiographical evaluationJournal of EndodonticsJournal of Endodontics219-242051994May7931011130 Apical clearing is generally performed when there is an apical stop and the master apical file is less that a size #40 file. If the apical configuration is open or a seat, apical clearing might make the opening larger and potentiate the possibility of extrusion of the obturation materials. Apical clearing consists of two distinct steps: final apical enlargement and dry reaming. Final apical enlargement is performed after the canal has been cleaned and shaped. It involves enlargement of the apical preparation three to five sizes beyond the master apical file (Figure 16-22). The degree of enlargement depends on the canal size and root curvature. In a small curved canal enlargement may only be three sizes to decrease the potential for transportation. In a straight canal it can be larger without producing a procedural error. Since the prepared canal exhibits taper, the small files at the corrected working length can be used to enlarge the canal without transportation. Final apical enlargement is performed with the irrigant and employs a reaming action at the corrected working length. The last file used becomes the final apical file. Since the file is only contacting the apical 1-2 mm the walls of the canal, the technique will result in a less irregular apical preparation. The canal is then irrigated. The smear layer is removed with a decalcifying agent and the canal dried with paper points. After drying the canals, the dry reaming is performed. Dry reaming removes dentin chips or debris packed apically during drying. The final apical file (or the master apical file in cases where apical enlargement was not performed) is placed to the corrected working length and rotated clockwise in a reaming action. Recapitulation Recapitulation is important regardless of the technique selected (Figure16-23). This is accomplished by taking a small file to the corrected working length to loosen accumulated debris and then flushing it with 1-2 ml of irrigant. Recapitulation is performed between each successive enlarging instrument regardless of the cleaning and shaping technique. Combination Technique This technique combines coronal flaring, nickel titanium rotary preparation, and the passive step-back technique (BOX-4). Following access, the canal is explored with a #10 or #15 file. If the canal is patent to the estimated working length a working length radiograph can be obtained and the corrected working length established (Chapter 15, Figure 15-40). In order to insure an accurate length determination a size #20 file or larger should be used (Chapter 15, Figures 15-40, 15-41). If a #20 file will not go to the estimated working length passive step-back instrumentation can be performed by inserting successively larger files to the point of binding and reaming. This removes coronal interferences and creates greater coronal taper permitting larger files access to the apical portion of the root. After establishing the working length, Gates Glidden drills are used for straight line access (Figure 16-18). A #2 Gates is used first followed by the #3 and #4. In very narrow canals a #1 Gates may be needed. It is important to remember the size of the Gates Glidden drills. If the canal orifice cannot accommodate a size #70 file, passive step back should be performed to provide adequate initial coronal space. To prevent stripping perforations, the Gates should not be placed apical to canal curvatures. Generally the #2-#4 provides adequate coronal enlargement and preserves root structure. The use of nickel titanium rotary instruments with greater tapers can also be used for this step (.06, .08, and .10 tapers are common). The Gates Glidden drills can be used in either a crown-down or step-back sequence. Following use, the Gates Glidden drill should be removed from the handpiece to prevent injury to the clinician, assistant or patient (Figure 16-24). Master Apical File Emphasis has traditionally been placed on determining the canal length with little consideration of the canal diameter in the apical portion of the root. Since every canal is unique in its morphology the apical canal diameter must be assessed. The size of the apical portion of the canal is determined by placing successively larger instruments to the corrected working length until slight binding is encountered (Figure 16-25). Often the next larger instrument will not go to the corrected working length. If it does go to length a subjective estimation of the apical diameter must be made depending on the degree of binding. This file will be the master apical file (initial file to bind). It is defined as the largest file to bind at the corrected working length following straight line access. This provides an estimate of the canal diameter before cleaning and shaping and it is the point where the step-back preparation begins. Nickel-Titanium Rotary Once the master apical file is identified, the middle to apical portion of the canal is prepared using nickel titanium rotary instruments (Figure 16-20 and Figure 16-21)). Rotary files are used with a crown-down approach to within 3 mm of the corrected working length. Adequate coronal taper is established when the .06/45 goes to within 3.0 mm of the corrected working length. Using the crown down approach creates coronal taper and reduces the contact area of the file so torsional forces are reduced. Recapitulation Recapitulation is accomplished after each instrument used in the canal by taking a small file to the corrected working length and then flushing the canal with 1-2 ml of irrigant (Figure 16-23). Step-Back Apical Preparation When the body of the canal has been shaped, the apical portion is prepared using standardized stainless steel or nickel titanium hand files in a step-back process (Figure 16-15). The first instrument selected for this portion of the shaping process is one size larger that the master apical file (initial file to bind slightly). Larger files are successively shortened by standardized increments of 0.05 mm or 1.0 mm. Generally sequentially stepping back to a file size of #60 or #70 will produce adequate flare and blend the apical and middle thirds of the canal. Apical Clearing With a flared preparation from the orifice to the corrected working length, the apical portion of the canal is enlarged. With a tapered preparation the canal can be enlarged with a reaming action as the canal walls will keep the instrument centered (Figure 16-25). Box-4 The Combination Technique Steps Canal negotiation Working length determination Straight line access Master apical file determination Rotary preparation of the middle one third of the root Apical step-back preparation Apical clearing General Considerations A Review The following principles and concepts should be applied regardless of the instruments or technique selected. 1. Initial canal exploration is always performed with smaller files to gauge canal size, shape, and configuration. 2. Files are always manipulated in a canal filled with an irrigant or lubricant present. 3. Copious irrigation is used between each instrument in the canal. 4. Coronal preflaring (passive step-back technique) with hand instruments will facilitate placing larger working length files (either hand or rotary) and will reduce procedural errors such as loss of working length and canal transportation. 5. Apical canal enlargement is gradual, using sequentially larger files from apical to coronal, regardless of flaring technique. 6. Debris is loosened and dentin is removed from all walls on the outstroke (circumferential filing) or with a rotating (reaming) action at or close to working length. 7. Instrument binding or dentin removal on insertion should be avoided. Files are teased to length using a watch winding or twiddling action. This is a back-and-forth rotating motion of the files (approximately a quarter turn) between the thumb and forefinger, continually working the file apically. Careful file insertion (twiddling) followed by planing on the outstroke will help to avoid apical packing of debris and minimize extrusion of debris into the periradicular tissues. 8. Reaming is defined as the clockwise rotation of the file. Generally the instruments are placed into the canal until binding is encountered. The instrument is then rotated clockwise 180-360 to cut and plane the walls. When withdrawn the instrument tip is pushed alternately against all walls. The pushing motion is analogous to the action of a paintbrush. Overall, this is a turn and pull. 9. Filing is defined as placing the file into the canal and withdrawing it along the path of insertion to scrap the wall. There is very little rotation on the outward cutting stroke. The scraping or rasping action removes the tissue and cuts superficial dentin from the canal wall. 10. Turn pull filing involves placing the file into the canal until binding. The instrument is then rotated to engage the dentin and withdrawn with lateral pressure against the canal walls. 11. Circumferential filing is used for canals that exhibit cross sectional shapes that are not round. The file is placed into the canal and withdrawn in a directional manner against the mesial, distal, buccal, and lingual walls. 12. Regardless of the technique, after each insertion the file is removed and the flutes are cleaned of debris; the file can then be reinserted into the canal to plane the next wall. Debris is removed from the file by wiping it with an alcohol-soaked gauze or cotton roll ADDIN EN.CITE Ferreira Murgel1990102101021017Ferreira Murgel, C. A.Walton, R. E.Rittman, B.Pecora, J. D.Department of Endodontics, University of Iowa, Iowa City.A comparison of techniques for cleaning endodontic files after usage: a quantitative scanning electron microscopic studyJ EndodJ Endod214-7165Comparative StudyDecontamination/ methodsEquipment ContaminationEthanolMicroscopy, Electron, ScanningRoot Canal Therapy/ instrumentationUltrasonics1990May0099-2399 (Print)2074413131. 13. The canal is effectively cleaned only where the files actually contact and plane the walls. Inaccessible regions are poorly cleaned or dbrided. 14. Recapitulation is done to loosen debris by rotating the master apical file or a smaller size at the corrected working length followed by irrigation to mechanically remove the material. During recapitulation the canal walls are not planed and the canal should not be enlarged. 15. Small, long, curved, round canals are the most difficult and tedious to enlarge. They require extra caution during preparation, being the most prone to loss of length and transportation. 16. Over enlargement of curved canals by files attempting to straighten themselves will to lead to procedural errors (Figure 16-11). 17. Overpreparation of canal walls toward the furcation may result in a stripping perforation in the danger zone where root dentin is thinner. 18. It is neither desirable nor necessary to try to remove created steps or other slight irregularities created during canal preparation. 19. Instruments, irrigants, debris, and obturating materials should be contained within the canal. These are all known physical or chemical irritants that will induce periradicular inflammation and may delay or compromise healing. 20. Creation of an apical stop may be impossible if the apical foramen is already very large. An apical taper (seat) is attempted, but with care. Overusing large files aggravates the problem by creating an even larger apical opening. 20. Forcing or locking (binding) files into dentin produces unwanted torsional force. This tends to untwist, wrap-up, either will weaken, and break the instrument. CRITERIA FOR EVALUATING CLEANING AND SHAPING Following the cleaning and shaping procedures the canal should exhibit glassy smooth walls and there should be no evidence of unclean dentin filings, debris, or irrigant in the canal. This is determined by pressing the MAF against each wall in an outward stroke. Shaping is evaluated by assessing the canal taper and identifying the apical configuration. For obturation with lateral compaction, the finger spreader should go loosely to within 1.0 mm of the corrected working length. For warm vertical compaction the plugger should reach to within 5 mm of the corrected working length (Figure 16-26). The apical configuration is identified as an apical stop, apical seat, or open. This is accomplished by placing the master apical file to the corrected working. If the master apical file goes past the corrected working length the apical configuration is open. If master apical file stops at the corrected working length a file one or two sizes smaller is placed to the corrected working length. If this file stops the apical configuration is a stop. When the smaller file goes past the corrected working length the apical configuration is a seat. INTRACANAL MEDICAMENTS Intracanal medicaments have a long history of use as interim appointment dressings. They are employed for three purposes: 1) to reduce inter-appointment pain, 2) to decrease the bacterial count and prevent regrowth, and 3) to render the canal contents inert. Some common agents are listed in Box 16-5 . Box 16-5 Groupings of Commonly Used Intracanal Medicaments PhenolicsEugenolCamphorated monoparachlorophenol (CMCP)Parachlorophenol (PCP)Camphorated parachlorophenol (CPC)Metacresylacetate (Cresatin)CresolCreosote (beechwood)ThymolAldehydesFormocresolGlutaraldehydeHalidesSodium hypochloriteIodine-potassium iodideSteroidsCalcium hydroxideAntibioticsCombinationsFrom Walton R: Intracanal medicaments, Dent Clin North Am 28:783, 1984. Phenols and aldehydes The majority of the medicaments exhibit non-specific action and can destroy host tissues as well as microbes ADDIN EN.CITE Chang1999101871018717Chang, Y. C.Tai, K. W.Chou, L. S.Chou, M. Y.Department of Periodontics, Chung Shan Medical and Dental College Hospital, Taichung, Taiwan, Republic of China.Effects of camphorated parachlorophenol on human periodontal ligament cells in vitroJ EndodJ Endod779-812512Anti-Infective Agents, Local/ toxicityCamphor/ toxicityCell Division/drug effectsCells, CulturedChlorophenols/ toxicityColorimetryDental Disinfectants/toxicityDose-Response Relationship, DrugDrug CombinationsHumansPeriodontal Ligament/cytology/ drug effectsRoot Canal Irrigants/ toxicity1999Dec0099-2399 (Print)10726519Spangberg1973102001020017Spangberg, L.Cellular reaction to intracanal medicamentsTrans Int Conf EndodTrans Int Conf Endod108-2350Anti-Bacterial Agents/therapeutic useAntisepsisBacteria/drug effectsCamphor/therapeutic useDental Pulp/drug effectsDental Pulp Cavity/microbiologyPhenols/therapeutic usePotassium Iodide/therapeutic useSodium Hypochlorite19730074-3054 (Print)4526993Spangberg1979101981019817Spangberg, L.Rutberg, M.Rydinge, E.Biologic effects of endodontic antimicrobial agentsJ EndodJ Endod166-7556AnimalsAnti-Infective Agents, Local/ adverse effectsCamphor/ adverse effectsCresols/ adverse effectsIntradermal TestsPhenols/ adverse effectsPotassium Iodide/ adverse effectsRatsRoot Canal Therapy1979Jun0099-2399 (Print)296259132-134. Historically it has been thought that these agents are effective; their use was based on opinion and empiricism. The phenols and aldehydes are toxic and the aldehydes are fixative agents ADDIN EN.CITE Harrison1979102081020817Harrison, J. W.Bellizzi, R.Osetek, E. M.The clinical toxicity of endodontic medicamentsJ EndodJ Endod42-752Chlorophenols/ toxicityComparative StudyFormocresols/ toxicityHumansRoot Canal Therapy/ adverse effectsToothache/classificationWater Intoxication1979Feb0099-2399 (Print)296243Thoden van Velzen1977101801018017Thoden van Velzen, S. K.Feltkamp-Vroom, T. M.Immunologic consequences of formaldehyde fixation of autologous tissue implantsJ EndodJ Endod179-8535AnimalsCollagen Diseases/transmissionFormaldehyde/ immunologyRabbitsTransplantation, Autologous/ adverse effects1977May0099-2399 (Print)266027135, 136. When placed in the radicular space they have access to the periradicular tissues and the systemic circulation ADDIN EN.CITE Myers1978102011020117Myers, D. R.Shoaf, H. K.Dirksen, T. R.Pashley, D. H.Whitford, G. M.Reynolds, K. E.Distribution of 14C-formaldehyde after pulpotomy with formocresolJ Am Dent AssocJ Am Dent Assoc805-13965AbsorptionAnimalsAutoradiographyCarbon Radioisotopes/metabolismFemaleFormaldehyde/blood/ metabolism/urineFormocresols/metabolism/ therapeutic useHaplorhiniIodine Radioisotopes/blood/metabolismMacaca mulattaMalePulpotomyResearch Support, U.S. Gov't, P.H.S.Time Factors1978May0002-8177 (Print)418090Walton1978102021020217Walton, R. E.Langeland, K.Migration of materials in the dental pulp of monkeysJ EndodJ Endod167-7746AnimalsDental Pulp/ physiologyHaplorhiniLymph Nodes/physiologyPeriodontium/physiologyPulpotomyRoot Canal Filling Materials/ pharmacologySilver/pharmacologyZinc Oxide-Eugenol Cement/pharmacology1978Jun0099-2399 (Print)106088137, 138 Research has demonstrated that their clinical use is not justified ADDIN EN.CITE Harrison1983102041020417Harrison, J. W.Gaumgartner, J. C.Svec, T. A.Incidence of pain associated with clinical factors during and after root canal therapy. Part 1. Interappointment painJ EndodJ Endod384-799AdolescentAdultAgedFemaleHumansMaleMiddle AgedPain/epidemiology/etiologyPain, Postoperative/epidemiology/etiologyPeriapical Diseases/ epidemiology/etiologyRoot Canal Therapy/adverse effectsToothache/ epidemiology/etiology1983Sep0099-2399 (Print)6579198Harrison1981102061020617Harrison, J. W.Baumgartner, C. J.Zielke, D. R.Analysis of interappointment pain associated with the combined use of endodontic irrigants and medicamentsJ EndodJ Endod272-676Camphor/adverse effectsChlorophenols/adverse effectsDrug Combinations/adverse effectsFormocresols/adverse effectsHumansHydrogen Peroxide/adverse effectsIrrigation/ adverse effectsRoot Canal Therapy/ adverse effectsSodium Hypochlorite/adverse effectsToothache/ etiologyWater/adverse effects1981Jun0099-2399 (Print)6942083Walton1984101631016317Walton, R. E.Intracanal medicamentsDent Clin North AmDent Clin North Am783-96284Anesthesia, Dental/methodsDental Pulp Cavity/drug effects/microbiologyDrug EvaluationDrug Evaluation, PreclinicalHumansRoot Canal Irrigants/adverse effects/ therapeutic useToothache/drug therapy1984Oct0011-8532 (Print)6594278Doran1998101621016217Doran, M. G.Radtke, P. K.U.S. Army Dental Clinic Command, Fort Meade, MD 20755, USA. mike_jeanb@hotmail.comA review of endodontic medicamentsGen DentGen Dent484-8; quiz 489-90465HumansRoot Canal Irrigants1998Sep-Oct0363-6771 (Print)10202494Bystrom1985101711017117Bystrom, A.Claesson, R.Sundqvist, G.The antibacterial effect of camphorated paramonochlorophenol, camphorated phenol and calcium hydroxide in the treatment of infected root canalsEndod Dent TraumatolEndod Dent Traumatol170-515Bacteria/drug effectsCalcium Hydroxide/ pharmacologyCamphor/ pharmacologyChlorophenols/ pharmacologyDental Pulp Diseases/microbiology/therapyDisinfectants/ pharmacologyDrug Combinations/pharmacologyHumansPhenols/ pharmacologyRoot Canal Irrigants/ pharmacologyRoot Canal Therapy1985Oct0109-2502 (Print)3865763139-143. Clinical studies assessing the ability of these agents to prevent or control interappointment pain indicate that they are not effective. ADDIN EN.CITE Maddox1977101721017217Maddox, D. Walton, RE. Davis, C.Incidence of post-treatment endodontic pain related to medicaments and other factorsJournal of EndodonticsJournal of Endodontics44731977Kleier1980101731017317Kleier, D. J.Mullaney, T. P.Effects of formocresol on posttreatment pain of endodontic origin in vital molarsJ EndodJ Endod566-965Clinical TrialsDouble-Blind MethodFormocresols/ therapeutic useHumansMolarPain, Postoperative/ prevention & controlRoot Canal Therapy/ adverse effectsToothache/ prevention & control1980May0099-2399 (Print)7005374Trope1990101751017517Trope, M.Department of Endodontology, Temple University School of Dentistry, Philadelphia.Relationship of intracanal medicaments to endodontic flare-upsEndod Dent TraumatolEndod Dent Traumatol226-965Acute DiseaseCalcium Hydroxide/adverse effectsChi-Square DistributionComparative StudyDemeclocycline/adverse effectsDrug CombinationsFormocresols/adverse effectsHumansPeriapical Periodontitis/ complicationsRecurrenceReoperationRoot Canal Irrigants/ adverse effectsRoot Canal Therapy/ adverse effectsToothache/etiologyTriamcinolone Acetonide/adverse effects1990Oct0109-2502 (Print)2133314Torabinejad1988101761017617Torabinejad, M.Kettering, J. D.McGraw, J. C.Cummings, R. R.Dwyer, T. G.Tobias, T. S.Factors associated with endodontic interappointment emergencies of teeth with necrotic pulpsJ EndodJ Endod261-6145AdultAge FactorsAgedAged, 80 and overEmergenciesFemaleHumansMaleMiddle AgedRetrospective StudiesRoot Canal Therapy/ adverse effectsSex Factors1988May0099-2399 (Print)3251982144-147 Calcium hydroxide One intracanal agent that is effective in inhibiting microbial growth in canals is calcium hydroxide ADDIN EN.CITE Law2004102671026717Law, A.Messer, H.Postgraduate Endodontics, School of Dental Science, University of Melbourne, Melbourne, Australia. amanda.law@bigpond.comAn evidence-based analysis of the antibacterial effectiveness of intracanal medicamentsJ EndodJ Endod689-943010Anti-Infective Agents, Local/ pharmacology/ therapeutic useBacteria/drug effectsCalcium Hydroxide/pharmacology/therapeutic useChlorhexidine/pharmacology/therapeutic useEvidence-Based MedicineFormocresols/pharmacology/therapeutic useHumansIodine Compounds/pharmacology/therapeutic usePeriapical Periodontitis/ drug therapy/microbiologyPhenols/pharmacology/therapeutic useRoot Canal Irrigants/ pharmacology/ therapeutic use2004Oct0099-2399 (Print)15448460148. It has antimicrobial action due to the alkaline pH and it may aid in dissolving necrotic tissue remnants and bacteria and their byproducts ADDIN EN.CITE Yang1995101701017017Yang, S. F.Rivera, E. M.Baumgardner, K. R.Walton, R. E.Stanford, C.Department of Restorative Dentistry, Veterans General Hospital, Taipei, Taiwan, ROC.Anaerobic tissue-dissolving abilities of calcium hydroxide and sodium hypochloriteJ EndodJ Endod613-62112AnaerobiosisAnimalsCalcium Hydroxide/ pharmacologyCattleComparative StudyDental Pulp/ drug effectsOxygenRandom AllocationRoot Canal Irrigants/ pharmacologySodium Hypochlorite/ pharmacologySolvents/ pharmacologyStatistics, Nonparametric1995Dec0099-2399 (Print)8596083Safavi1994101681016817Safavi, K. E.Nichols, F. C.Department of Restorative Dentistry and Endodontology, School of Dental Medicine, University of Connecticut Health Center, Farmington 06030.Alteration of biological properties of bacterial lipopolysaccharide by calcium hydroxide treatmentJ EndodJ Endod127-9203Calcium Hydroxide/chemistry/ pharmacologyFatty Acids/analysisHumansHydroxylationLipopolysaccharides/ chemistry/immunologyMonocytes/metabolismPrevotella intermediaProstaglandins E/biosynthesisRoot Canal Irrigants/ pharmacologySalmonella typhimuriumStructure-Activity Relationship1994Mar0099-2399 (Print)7996084Safavi1993101691016917Safavi, K. E.Nichols, F. C.Department of Restorative Dentistry and Endodontology, University of Connecticut Health Center, School of Dental Medicine, Farmington.Effect of calcium hydroxide on bacterial lipopolysaccharideJ EndodJ Endod76-8192Calcium Hydroxide/ pharmacologyDecanoic Acids/analysisLipolysisLipopolysaccharides/ chemistryMyristic Acids/analysisPalmitic Acids/analysisPolysaccharides, Bacterial/ drug effectsRoot Canal Irrigants/pharmacologySalmonella typhimurium1993Feb0099-2399 (Print)8509740149-151. Interappointment calcium hydroxide in the canal demonstrates no pain reduction effects ADDIN EN.CITE Walton2003101641016417Walton, R. E.Holton, I. F., Jr.Michelich, R.Department of Endodontics, University of Iowa College of Dentistry, Iowa City 52242-1001, USA.Calcium hydroxide as an intracanal medication: effect on posttreatment painJ EndodJ Endod627-92910AdultCalcium Hydroxide/ therapeutic useFemaleHumansMalePain MeasurementPain, Postoperative/ prevention & controlRegression AnalysisRoot Canal Irrigants/ therapeutic useToothache/ prevention & control2003Oct0099-2399 (Print)14606782152. Calcium hydroxide has been recommended for use in teeth with necrotic pulp tissue and bacterial contamination. It probably has little benefit with vital pulps. Calcium hydroxide can be placed as a dry powder, a powder mixed with a liquid such as local anesthetic solution, saline, water, or glycerin to form a thick paste, or as a proprietary paste supplied in a syringe (Figure 16-27). A lentulo-spiral is effective and efficient. ADDIN EN.CITE Torres2004121217Torres, C. P.Apicella, M. J.Yancich, P. P.Parker, M. H.US Army Endodontic Residency Program at Fort Bragg, NC, USA. craig.torres@ng.gmedd.army.milIntracanal placement of calcium hydroxide: a comparison of techniques, revisitedJournal of EndodonticsJournal of Endodontics225-73042004Apr15085051Rivera1994101861018617Rivera, E. M.Williams, K.Department of Endodontics, College of Dentistry, University of Iowa, Iowa City.Placement of calcium hydroxide in simulated canals: comparison of glycerin versus waterJ EndodJ Endod445-8209Calcium Hydroxide/ chemistryComparative StudyGlycerolModels, StructuralObserver VariationResearch Support, U.S. Gov't, P.H.S.Root Canal IrrigantsRoot Canal Obturation/ methodsSpecific GravityWater1994Sep0099-2399 (Print)7996115Sigurdsson1992101831018317Sigurdsson, A.Stancill, R.Madison, S.School of Dentistry, University of North Carolina at Chapel Hill.Intracanal placement of Ca(OH)2: a comparison of techniquesJ EndodJ Endod367-70188Calcium Hydroxide/ administration & dosageComparative StudyHumansMolarRoot Canal Irrigants/ administration & dosageRoot Canal Therapy/ methods1992Aug0099-2399 (Print)1431690153-155 Spinning the paste into the canal by rotating a file counterclockwise and using an injection technique is not as effective. It is important to place the material deeply and densely for maximum effectiveness. To accomplish this straight line access with Gates Glidden drills or nickel-titanium rotary files should be performed and the apical portion of the canal prepared to a size #25 file or greater. Removal following placement is difficult. ADDIN EN.CITE Lambrianidis2006103311033117Lambrianidis, T.Kosti, E.Boutsioukis, C.Mazinis, M.Department of Endodontology, Dental School, Aristotle University of Thessaloniki, Thessaloniki, Greece.Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canalInt Endod JInt Endod J55-61391Calcium HydroxideChlorhexidineComparative StudyDisinfectantsEdetic Acid/ administration & dosageHumansRoot Canal Irrigants/ administration & dosageRoot Canal Therapy/ instrumentationSodium Hypochlorite/ administration & dosageStatistics, Nonparametric2006Jan0143-2885 (Print)16409329156 This is especially true in the apical portion of the root. Corticosteroids Corticosteroids are anti-inflammatory agents that have been advocated for decreasing postoperative pain by suppressing inflammation. The use of corticosteroids as intracanal medicaments may decrease lower levels postoperative pain in certain situations; ADDIN EN.CITE Ehrmann2003102111021117Ehrmann, E. H.Messer, H. H.Adams, G. G.School of Dental Science, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 711 Elizabeth Street, Melbourne, Victoria, 3000, Australia. eehrmann@melbpc.org.auThe relationship of intracanal medicaments to postoperative pain in endodonticsInt Endod JInt Endod J868-753612Anti-Bacterial Agents/therapeutic useCalcium Hydroxide/therapeutic useCalcium SulfateDemeclocycline/ therapeutic useDental Pulp Necrosis/ therapyDrug CombinationsEmergency TreatmentGlucocorticoids/ therapeutic useHumansMethylmethacrylatesPain MeasurementPain, Postoperative/ prevention & controlPeriapical Periodontitis/ therapyPolyvinylsProspective StudiesRoot Canal Filling MaterialsRoot Canal Irrigants/ therapeutic useRoot Canal ObturationSingle-Blind MethodToothache/ prevention & controlTriamcinolone Acetonide/ therapeutic useZinc OxideZinc Oxide-Eugenol Cement2003Dec0143-2885 (Print)14641427157 however, evidence also suggests that they may be ineffective particularly with greater pain levels ADDIN EN.CITE Trope1990102121021217Trope, M.Department of Endodontology, Temple University School of Dentistry, Philadelphia.Relationship of intracanal medicaments to endodontic flare-upsEndod Dent TraumatolEndod Dent Traumatol226-965Acute DiseaseCalcium Hydroxide/adverse effectsChi-Square DistributionComparative StudyDemeclocycline/adverse effectsDrug CombinationsFormocresols/adverse effectsHumansPeriapical Periodontitis/ complicationsRecurrenceReoperationRoot Canal Irrigants/ adverse effectsRoot Canal Therapy/ adverse effectsToothache/etiologyTriamcinolone Acetonide/adverse effects1990Oct0109-2502 (Print)2133314147. Cases irreversible pulpitis and cases where the patient is experiencing acute apical periodontitis are examples where steroid use might be beneficial ADDIN EN.CITE Ehrmann2003102111021117Ehrmann, E. H.Messer, H. H.Adams, G. G.School of Dental Science, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 711 Elizabeth Street, Melbourne, Victoria, 3000, Australia. eehrmann@melbpc.org.auThe relationship of intracanal medicaments to postoperative pain in endodonticsInt Endod JInt Endod J868-753612Anti-Bacterial Agents/therapeutic useCalcium Hydroxide/therapeutic useCalcium SulfateDemeclocycline/ therapeutic useDental Pulp Necrosis/ therapyDrug CombinationsEmergency TreatmentGlucocorticoids/ therapeutic useHumansMethylmethacrylatesPain MeasurementPain, Postoperative/ prevention & controlPeriapical Periodontitis/ therapyPolyvinylsProspective StudiesRoot Canal Filling MaterialsRoot Canal Irrigants/ therapeutic useRoot Canal ObturationSingle-Blind MethodToothache/ prevention & controlTriamcinolone Acetonide/ therapeutic useZinc OxideZinc Oxide-Eugenol Cement2003Dec0143-2885 (Print)14641427Chance1988102131021317Chance, K. B.Lin, L.Skribner, J. E.Corticosteroid use in acute apical periodontitis: a review with clinical implicationsClin Prev DentClin Prev Dent7-10101Adrenal Cortex Hormones/ therapeutic useAnimalsHumansPeriapical Periodontitis/ drug therapy1988Jan-Feb0163-9633 (Print)3078589Chance1987102141021417Chance, K.Lin, L.Shovlin, F. E.Skribner, J.Clinical trial of intracanal corticosteroid in root canal therapyJ EndodJ Endod466-8139Clinical TrialsDental Pulp CavityDouble-Blind MethodHumansPain, Postoperative/ prevention & controlPrednisolone/administration & dosage/ analogs & derivativesResearch Support, Non-U.S. Gov'tRoot Canal Therapy/adverse effects1987Sep0099-2399 (Print)3328770158, 159, 157. Chlorhexidine Chlorhexidine has recently been advocated as an intracanal medicament. ADDIN EN.CITE Dammaschke2005103321033217Dammaschke, T.Schneider, U.Stratmann, U.Yoo, J. M.Schafer, E.Poliklinik fur Zahnerhaltung, Westfalische Wilhelms-Universitat, Munster, Germany. tillda@uni-muenster.deEffect of root canal dressings on the regeneration of inflamed periapical tissueActa Odontol ScandActa Odontol Scand143-52633Analysis of VarianceAnimalsAnti-Infective Agents, Local/pharmacology/therapeutic useCalcium Hydroxide/pharmacology/therapeutic useChlorhexidine/pharmacology/therapeutic useComparative StudyFemaleMalePeriapical Periodontitis/ drug therapyRatsRats, WistarRegeneration/ drug effectsRoot Canal Irrigants/pharmacology/ therapeutic useStatistics, Nonparametric2005Jun0001-6357 (Print)16191907Dametto2005103341033417Dametto, F. R.Ferraz, C. C.de Almeida Gomes, B. P.Zaia, A. A.Teixeira, F. B.de Souza-Filho, F. J.Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.In vitro assessment of the immediate and prolonged antimicrobial action of chlorhexidine gel as an endodontic irrigant against Enterococcus faecalisOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod768-72996Anti-Infective Agents, Local/ administration & dosageBicuspidChlorhexidine/administration & dosage/ analogs & derivativesColony Count, MicrobialEnterococcus faecalis/ drug effectsGelsHumansResearch Support, Non-U.S. Gov'tRoot Canal Irrigants/ administration & dosageRoot Canal Preparation/ methodsSodium Hypochlorite/pharmacologyStatistics, Nonparametric2005Jun1528-395X (Electronic)15897866160, 161 A 2% gel is recommended. It can be used alone in gel form or mixed with calcium hydroxide. When used with calcium hydroxide the antimicrobial activity is greater than when calcium hydroxide is mixed with saline ADDIN EN.CITE Gomes2006103231032317Gomes, B. P.Vianna, M. E.Sena, N. T.Zaia, A. A.Ferraz, C. C.de Souza Filho, F. J.Department of Restorative Dentistry, State University of Campinas, Piracicaba, SP, Brazil. bpgomes@fop.unicamp.brIn vitro evaluation of the antimicrobial activity of calcium hydroxide combined with chlorhexidine gel used as intracanal medicamentOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod544-501024Anti-Infective Agents, Local/ pharmacologyBacteria/ drug effectsCalcium Hydroxide/pharmacologyCandida albicans/drug effectsChlorhexidine/pharmacologyComparative StudyDental Pulp Cavity/microbiologyDrug CombinationsEnterococcus faecalis/drug effectsImmunodiffusionPorphyromonas endodontalis/drug effectsPorphyromonas gingivalis/drug effectsPrevotella intermedia/drug effectsResearch Support, Non-U.S. Gov'tRoot Canal Irrigants/ pharmacologyStaphylococcus aureus/drug effects2006Oct1528-395X (Electronic)16997123162and periradicular healing is enhanced. ADDIN EN.CITE De Rossi2005103351033517De Rossi, A.Silva, L. A.Leonardo, M. R.Rocha, L. B.Rossi, M. A.Department of Pathology, University of Sao Paulo and State University of Sao Paulo, Brazil. andiaraderossi@bol.com.brEffect of rotary or manual instrumentation, with or without a calcium hydroxide/1% chlorhexidine intracanal dressing, on the healing of experimentally induced chronic periapical lesionsOral Surg Oral Med Oral Pathol Oral Radiol EndodOral Surg Oral Med Oral Pathol Oral Radiol Endod628-36995Analysis of VarianceAnimalsCalcium Hydroxide/pharmacology/therapeutic useChlorhexidine/pharmacology/therapeutic useChronic DiseaseDental InstrumentsDogsDrug CombinationsPeriapical Periodontitis/radiography/ therapyResearch Support, Non-U.S. Gov'tRoot Canal Irrigants/pharmacology/ therapeutic useRoot Canal Preparation/ instrumentationWound Healing/drug effects2005May1528-395X (Electronic)15829889163 Its major disadvantages are; it does not affect the smear layer and it is a fixative. TEMPORARY RESTORATIONS (Courtesy of Dr. Harold Messer) Root canal treatment may involve multiple visits. Also, unless it is limited to a routine access cavity, the final restoration is usually not completed in the same appointment as the root canal treatment. A temporary restoration is then required, normally for 1 to 4 weeks. In special situations when definitive restoration must be deferred, the temporary must last several months. Objectives of Temporization The temporary restoration must 1. Seal coronally, preventing ingress of oral fluids and bacteria and egress of intracanal medicaments. Enhance isolation during treatment procedures. Protect tooth structure until the final restoration is placed. 4. Allow ease of placement and removal. 5. Satisfy esthetics, but always as a secondary consideration to providing a seal. These objectives depend on the intended duration of use. Thus, different materials are required depending on time, occlusal load and wear, complexity of access, and loss of tooth structure. Routine Access Cavities Most access cavities involve only one surface and are surrounded by dentin walls or by porcelain or metal (if the restoration is retained). The temporary must last from several days to several weeks. Numerous types are available, including premixed cements that set on contact with moisture (Cavit), reinforced zinc oxide-eugenol cements (such as IRM), glass ionomer cements and specially formulated light-polymerized composite materials (such as TERM, temporary endodontic restorative material) ADDIN EN.CITE Naoum20021147114717Naoum, H. J.Chandler, N. P.Brindabella Specialist Centre, 5 Dann Close, GARRAN, ACT 2605, Australia.Temporization for endodonticsInternational Endodontic JournalInternational Endodontic Journal964-7835122002Dec12653314164. Ease of use and good sealing ability make Cavit an excellent routine material, but low strength and rapid occlusal wear limit its use to short-term sealing of simple access cavities. IRM and TERM provide improved wear resistance, although their sealing ability is probably marginally less than that of Cavit ADDIN EN.CITE Barthel2001103131031317Barthel, C. R.Zimmer, S.Wussogk, R.Roulet, J. F.Department of Operative and Preventive Dentistry and Endodontics, Humboldt University Berlin, Germany.Long-Term bacterial leakage along obturated roots restored with temporary and adhesive fillingsJ EndodJ Endod559-62279Chi-Square DistributionComparative StudyDental CementsDental LeakageDental Restoration, TemporaryDentin-Bonding AgentsGlass Ionomer CementsHumansIncisorMaleatesMethylmethacrylatesResin CementsRoot Canal Filling MaterialsRoot Canal Obturation/ methodsStaphylococcus epidermidis/isolation & purificationStatistics, NonparametricTime FactorsWaxesZinc Oxide-Eugenol Cement2001Sep0099-2399 (Print)11556557Zmener2004103171031717Zmener, O.Banegas, G.Pameijer, C. H.Department of Adult Dental Care, Section of Endodontics, Faculty of Odontology, University of Buenos Aires, Buenos Aires, Argentina. Zmener@infovia.com.arCoronal microleakage of three temporary restorative materials: an in vitro studyJ EndodJ Endod582-4308Acid Etching, DentalAcrylic Resins/chemistryCalcium Sulfate/chemistryColoring Agents/diagnostic useDental BondingDental Cavity PreparationDental Cements/ chemistryDental Enamel/ultrastructureDental Leakage/ classificationDental Restoration, Temporary/adverse effectsDentin/ultrastructureDrug CombinationsHumansMarginal Adaptation (Dentistry)Materials TestingMethylene Blue/diagnostic useMethylmethacrylates/chemistryPolycarboxylate Cement/chemistryPolyvinyls/chemistrySurface PropertiesTemperatureZinc Oxide/chemistryZinc Oxide-Eugenol Cement/chemistry2004Aug0099-2399 (Print)15273640165, 166. More durable restorative materials, especially glass ionomer cements, tend to provide the best seal. A double seal of GIC over Cavit will provide a durable and effective barrier to microbial leakage. It is not known whether experimental leakage differences based on bacterial leakage or dye penetration are significant clinically, especially if thermocycling and occlusal loading are not part of the testing procedure ADDIN EN.CITE Mayer1997103151031517Mayer, T.Eickholz, P.Department of Restorative Dentistry, Ruprecht-Karls-University, Heidelberg, Germany.Microleakage of temporary restorations after thermocycling and mechanical loadingJ EndodJ Endod320-2235Calcium SulfateComparative StudyComposite ResinsDental Leakage/diagnosisDental Restoration, TemporaryDrug CombinationsHumansMethylmethacrylatesMicroscopy, Electron, ScanningPolyvinylsRoot Canal Filling MaterialsRoot Canal Obturation/methodsStatistics, NonparametricZinc OxideZinc Oxide-Eugenol Cement1997May0099-2399 (Print)9545936167. Clinically, 4mm of Cavit provided an effective seal against bacterial penetration for 3 weeks ADDIN EN.CITE Beach1996103141031417Beach, C. W.Calhoun, J. C.Bramwell, J. D.Hutter, J. W.Miller, G. A.Naval Dental School, Bathesda, MD, USA.Clinical evaluation of bacterial leakage of endodontic temporary filling materialsJ EndodJ Endod459-62229Calcium SulfateChi-Square DistributionColony Count, MicrobialComparative StudyComposite ResinsDental Leakage/etiology/microbiologyDental Pulp Cavity/ microbiologyDental Restoration, Temporary/ adverse effectsDrug CombinationsEvaluation StudiesHumansMarginal Adaptation (Dentistry)MethylmethacrylatesPolyvinylsRoot Canal Filling Materials/adverse effectsStatistics, NonparametricZinc OxideZinc Oxide-Eugenol Cement1996Sep0099-2399 (Print)9198425168. Most critical are the thickness and placement of the material. Techniques of Placement - The quality of the coronal seal depends on the thickness of the material, how it is compacted into the cavity, and the extent of contact with sound tooth structure or restoration. A minimum depth of 3 to 4 mm is required around the periphery, preferably 4 mm or more to allow for wear. In anterior teeth, the access is oblique to the tooth surface; care must be taken to ensure that the material is at least 3 mm thick in the cingulum area. Cavit (or a similar material) is placed as follows: Chamber and cavity walls should be dry. Cavit can be placed directly over the canal orifices, or more commonly a thin layer of cotton is placed over the canal orifices to prevent canal blockage ADDIN EN.CITE Vail2006102301023017Vail, M. M.Steffel, C. L.Indiana University School of Dentistry, Indianapolis, Indiana 46202, USA. mvail@iupui.eduPreference of temporary restorations and spacers: a survey of Diplomates of the American Board of EndodontistsJ EndodJ Endod513-5326Attitude of Health PersonnelDental Restoration, Temporary/ methodsEndodontics/ methodsHealth Care SurveysHumansRoot Canal Therapy/ methodsSocieties, DentalUnited States2006Jun0099-2399 (Print)16728239169. (Figure 16-28) Care must be taken not to incorporate cotton fibers into the restorative material, which can promote rapid leakage ADDIN EN.CITE Newcomb20011458145817Newcomb, B. E.Clark, S. J.Eleazer, P. D.University of Louisville School of Dentistry, KY, USA.Degradation of the sealing properties of a zinc oxide-calcium sulfate-based temporary filling material by entrapped cotton fibersJournal of EndodonticsJournal of Endodontics789-9027122001Dec11771593170. Cavit is packed into the access opening with a plastic instrument in increments from the bottom up and pressed against the cavity walls and into undercuts (Figure 16-29). Excess is removed, and the surface smoothed with moist cotton. The patient should avoid chewing on the tooth for at least an hour. Subsequent removal using a high speed bur requires care to avoid damage to the access opening. Alternatively, an ultrasonic tip can be used. Extensive Coronal Breakdown Teeth without marginal ridges or with undermined cusps require a stronger filling material (high-strength glass ionomer cement), taking care to ensure an adequate thickness and good marginal adaptation proximally. The temporary filling material should extend well into the pulp chamber deep to the proximal margin to ensure a marginal seal. Reducing the height of undermined cusps well out of occlusion reduces the risk of fracture. For severely broken-down teeth, a cusp-onlay amalgam or a well-fitting orthodontic band cemented onto the tooth (restored with glass ionomer cement) provides a durable temporary restoration and strengthens the tooth against fracture ADDIN EN.CITE Pane2002103161031617Pane, E. S.Palamara, J. E.Messer, H. H.School of Dental Science, University of Melbourne, Melbourne, Australia.Stainless steel bands in endodontics: effects on cuspal flexure and fracture resistanceInt Endod JInt Endod J467-71355AdolescentBicuspid/ physiologyBite ForceCase-Control StudiesChildDental Cavity Preparation/instrumentationDental Enamel/ physiologyDental Stress Analysis/instrumentationEquipment DesignHumansLinear ModelsMatched-Pair AnalysisMatrix BandsPliabilityResearch Support, Non-U.S. Gov'tRoot Canal Preparation/instrumentationStainless SteelStatisticsStress, MechanicalTooth Fractures/physiopathology2002May0143-2885 (Print)12059919171. At the next appointment, access is prepared through the restoration. Provisional Post Crowns The use of a provisional crown with an incorporated resin post may be required, particularly when a cast post and core is being fabricated for a visible tooth with little remaining coronal tooth structure. However, the use of such a provisional crown retained with a post (preformed aluminum post, safety pin wire, paper clip, or a sectioned large endodontic file) has inherent problems. Using the canal space for a provisional post precludes use of an intracanal medicament, and the coronal seal depends entirely on the cement. The coronal seal is generally inadequate with a loosely fitting and mobile provisional post and crown ADDIN EN.CITE Gutmann19923456345617Gutmann, J. L.Department of Endodontics, Baylor College of Dentistry, Dallas, Tex.The dentin-root complex: anatomic and biologic considerations in restoring endodontically treated teethJournal of Prosthetic DentistryJournal of Prosthetic Dentistry458-676741992Apr1507126172. However, in spite of these potential difficulties, such provisional restorations may be required while cast posts and cores are being fabricated. Due to the potential problems, it is prudent to cement the definitive post as soon as possible. When such a provisional crown-post combination is being used, the post should fit the canal snugly (not binding) and extend apically 4 to 5 mm short of working length and coronally to within 2 to 3 mm of the incisal edge. A polycarbonate shell is trimmed to a good fit; autopolymerizing material then is added to the inside of the shell to mold to the root face and attach to the post. A provisional luting cement (Temp Bond or similar cement) is placed on the coronal 3 to 4 mm of the post and root face, and the unit is cemented into place. A provisional removable partial overdenture is a useful alternative; access remains excellent, and there is little chance of disturbing the coronal seal between appointments. Longterm Temporary Restorations Few indications exist to justify delaying the final restoration, and endodontic procedures (other than trauma management) rarely require prolonged treatment. If a temporary restoration has to last more than a few weeks, then a durable material such as amalgam, glass ionomer cement, or acid-etch composite should be used. The pulp chamber is filled with Cavit to provide a good coronal seal, and covered with a sufficient thickness of the restorative material to ensure strength and wear resistance. Subsequent access to the canal space is readily achieved without damage to remaining tooth structure because the layer of Cavit can be easily removed. Figures Figure 16-1 Cross-section through a root showing the main canal (C) and a fin (arrow) and associated cul-de-sac after cleaning and shaping, using files and sodium hypochlorite. Note the tissue remnants that remain in the fin. Figure 16-2 The main canal (C) has a lateral canal (arrow) extending to the root surface. After cleaning and shaping with sodium hypochlorite irrigation, tissue remains in the lateral canal. Figure 163 A. A size #15 file in the apical canal space. Note the size is inadequate for planning the walls. B. A size #40 file more closely approximates the canal morphology (Courtesy of Dr. Randy Madsen). Figure 16-4 A. The classic apical anatomy consisting of the major diameter of the foramen and the minor diameter of the constriction. B. An irregular ovoid apical canal shape and external resorption. C. A bowling pin apical morphology and an accessory canal. D. Multiple apical foramina. Figure 16-5 A small file (#10 or #15) is placed beyond the radiographic apex to maintain patency of the foramen. Note the tip extends beyond the apical foramen (arrow). Figure 16-6 For effective irrigation the needle must be placed in the apical one-third of the root and must not bind. Figure 16-7 A sodium hypochlorite accident during treatment of the maxillary left central incisor. Extensive edema occurred in the upper lip accompanied by severe pain. Figure 16-8 A. A canal wall with the smear layer present. B. The smear layer removed it 17% EDTA. Figure 16-9 Procedural errors of canal transportation, zipping and strip perforation occur during standardized preparation when files remove dentin from the outer canal wall apical to the curve and from the inner wall coronal to the curve. This is related to the restoring force (stiffness) of the files. Note in the apical portion the transportation takes the shape of a tear drop as the larger files are used. Figure 16-10 The canals have been transported and there is an apical perforation. Figure 16-11 A. A size #35 file fractured in the mesiobuccal canal. B. SEM examination reveals torsional fatigue at the point of fracture. Note the tightening of the flutes near the fracture and the unwinding of the flutes along the shaft. Figure 16-12 A. The furcal region of molars at the level of the curvature (danger zone) is a common site for stripping perforation. B. Note the distal concavity (arrows) in the furcation area of this mandibular molar. Figure 16-13 Straight line access can result in stripping perforations in the furcal areas of molars. A. The use of large Gates Glidden drills and overpreparation has resulted in the stripping perforation. B. Note that the perforation is in the concavity of the furcation. Figure 16-14 The step-back preparation is designed to provide a tapering preparation. The process begins with one file size larger than the master apical file with incremental shortening of either .5 or 1.0 mm. Figure 16-15 As an example of step-back preparation in a moderately curved canal. A. The size #25 master apical file at the corrected working length of 21.0 mm. B. The step-back process begins with the #30 file at 20.5 mm. C. #35 at 20.0 mm. D. #40 file at 19.5 mm. E. #45 file at 19.0 mm. F. #50 file at 18.5 mm. G. #55 file at 18.0 mm. H. #60 file at 17.5 mm. I. #70 file at 17.0 mm Figure 16-16 Passive step-back. Smaller to larger files are inserted to their initial point of binding and then rotated 180 to 360 and withdrawn. This process creates slight taper and coronal space. This permits larger instruments to reach the apical one third. Figure 16-17 The anti-curvature filing technique. Instruments are directed away from the furcal danger zone toward the line angles (safety zone) where the bulk of dentin is greater. Figure 16-18 Straight line access in a maxillary left first molar with Gates-Glidden drills used in a slow speed handpiece using a step-back technique. A. The #1 Gates is used until resistance. B. This is followed by the #2 which should not go past the first curvature. C. The #3 Gates is used 3-4 mm into the canal. D. Followed by the #4 instrument. Figure 16-19 A maxillary first molar following straight line access with the Gates Glidden Drills. Figure 16-20 The mesiobuccal canal is prepared using nickel-titanium rotary files using a crown-down technique. In this sequence each instrument exhibits the same .06 taper with varied ISO standardized tip diameters. Instrument were used to resistance. A. The process begins with a .06\45 file to resistance at 16.0 mm. B. This is followed by a .06\40 instrument at 17.0 mm C. The .06\35 file is used to 18.0 mm. D. The .06\30 at 19.0 mm. E. The .06\25 at 20.0 mm. F. The .06\20 file is to the corrected working length of 21.0mm. Figure 16-21 Nickel-titanium rotary files with a standardized ISO tip diameter and variable tapered files can be used in canal preparation. In this sequence, the instruments have a standardized tip diameter of .20 mm. A. Initially a 10/.0 file is used. B. This is followed by 08/.20. C. The third instrument is a .06/.20. D. The final instrument is a 04/.20 file to the corrected working length of 21.0 mm. Figure 16-22 Final Apical Enlargement A. The master apical file of size #25 at the corrected working length of 21.0 mm. B. Enlargement with a #30 file to the corrected working length of 21.0 mm. C. Further enlargement with a #35 file. D. Final enlargement to a size #40 file. The final instrument used becomes the Final Apical File. Figure 16-23 Recapitulation is accomplished between each instrument by reaming with the Master Apical File or a smaller instrument. This minimizes packing of debris and loss of length. Figure 16-24 Following their use, the Gates Glidden drills should be removed from the handpiece to prevent injury. This #3 drill was accidentally driven into the palm of the dentist. Figure 16-25 Following straight line access in this maxillary molar, the Master Apical File is determined by successively placing small to larger files to the corrected working length. A. A #15 stainless steel file is placed to 21.0 mm without resistance. B. A #20 is the placed is placed to 21.0 mm without resistance. C. The #25 file reaches 21.0 mm with slight binding. D. A size #30 file is then placed and does not go the corrected working length indicating the initial canal size in the apical portion of the canal is a size#25 Figure 16-26 The coronal taper is assessed using the spreader or plugger depth of penetration. A. With lateral compaction a finger spreader should fit loosely 1.0 mm from the Corrected Working Length with space adjacent to the spreader. B. For warm vertical compaction, the plugger should go to within 5.0 mm of the Corrected Working Length. Figure 16-27 Calcium hydroxide placement. A. Calcium hydroxide mixed with glycerin to form a thick paste. B. Placement with a lentulo spiral. C. Injection of a proprietary paste. D. Compaction of calcium hydroxide powder with a plugger. Figures 16-28 and 16-29 are provided by Dr. Harold Messer Figure 16-28. Techniques for temporization. On the left are the correct techniques; either minimal space is occupied by cotton or no cotton pellet is used, particularly if the proximal is to be restored. It is wrong to pack most of the chamber with cotton, which leaves inadequate space and strength for the material (3-4 mm are required), and cotton fibers may promote bacterial leakage. (Courtesy of Dr L Wilcox) Figure 16-29. Techniques for placing temporary material. A, A single large blob placed in the access opening will not seal the walls. B, The incremental technique, which adds successive layers, pressing each against the chamber walls, is correct. (Courtesy of Dr L Wilcox) References  ADDIN EN.REFLIST 1. Ingle JI, editor. Endodontics. 5th Edition ed ed. Hamilton, London: BC Decker, Inc 2002. 2. Sabeti MA, Nekofar M, Motahhary P, Ghandi M, Simon JH. Healing of apical periodontitis after endodontic treatment with and without obturation in dogs. J Endod 32(7):628-33, 2006. 3. Delivanis PD, Mattison GD, Mendel RW. The survivability of F43 strain of Streptococcus sanguis in root canals filled with gutta-percha and Procosol cement. J Endod 9(10):407-10, 1983. 4. Walton RE. 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Journal of Prosthetic Dentistry 67(4):458-67, 1992.      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