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Assoc. Prof. Dr. Atakan KALENDER Learning Objectives     At end of this course students should be able to; Describe the importance of root canal preparation List the steps of cleaning and shaping Describe and learn to perform step-back technique ART AND SCIENCE OF DIAGNOSIS  Diagnosis i...

Assoc. Prof. Dr. Atakan KALENDER Learning Objectives     At end of this course students should be able to; Describe the importance of root canal preparation List the steps of cleaning and shaping Describe and learn to perform step-back technique ART AND SCIENCE OF DIAGNOSIS  Diagnosis is the art and science of detecting and distinguishing deviations from health and the cause and nature thereof.  The purpose of a diagnosis is to determine what problem the patient is having and why the patient is having that problem.  This will directly relate to what treatment, if any, will be necessary The process of making a diagnosis can be divided into five stages:      1. The patient tells the clinician the reasons for seeking advice. 2. The clinician questions the patient about the symptoms and history that led to the visit. 3. The clinician performs objective clinical tests. 4. The clinician correlates the objective findings with the subjective details and creates a tentative list of differential diagnosis. 5. The clinician formulates a definitive diagnosis. CLEANING AND SHAPING THE ROOT CANAL SYSTEM Assoc. Prof. Dr. Atakan KALENDER Tooth Morphology, Isolation, and Access OBJECTIVES & GUIDELINES FOR ACCESS CAVITY PREPARATION ? RUBBER DAM ENDODONTIC INSTRUMENTS Tirnerf K-File Reamer Hedstr STEPS OF CLEANING AND SHAPING Access Principles STEPS OF CLEANING AND SHAPING Coronal Preflaring The extension of an access cavity into the coronal-most portion of the root canal is called coronal flaring. STEPS OF CLEANING AND SHAPING Patency File A patency file is a small K-file (usually a size #10 or #15) that is passively extended slightly beyond the apical foramen. This step is thought to remove accumulated debris, to help maintain working length, and to translate into greater clinical success STEPS OF CLEANING AND SHAPING Working Length Determination WORKING LENGTH the distance from a coronal reference point to the point at which canal preparation and obturation should terminate ANATOMICAL CONSIDERATIONS •Anatomic apex: is the tip or end of the root determined morphologically •Radiographic apex: is the tip or end of the root determined radiographically. • Apical foramen (Major diameter): is the main apical opening of the root canal. •it is frequently eccentrically located away from the anatomic or radiographic apex. APİCAL CONSTRUCTION Minor diameter is the apical portion of the root canal having the narrowest diameter Cementodentinal Junction is the region where the dentin and cementum are united. It is a histological landmark and cannot be located clinically or radiographically. The CDJ does not always coincide with apical constriction and is located 0.5 -3mm short of anatomic apex Kanal Boyu Tespiti METHODS OF WORKING LENGTH DETERMINATION RADIOGRAPHICAL METHOD 1.Grossman’s formula NON RADIOGRAPHICAL METHOD 2. Ingles method 1.Digital tactile sense 3.Weine’s method 2.Apical periodontal sensitivity 4.Radiovisiography 5.Xeroradiography 3.Paper point method 4.Electonic apex locator GROSSMAN’S METHOD A, The length of the tooth is measured on the radiograph B, The length of the instrument is measured on the radiograph. C, The length of the instrument is measured on a ruler B A X= ? C A=Radiographic length of tooth B=Radiographic length of instrument C=Actual Length of instrument X=Actual Length of tooth A/X=B/C Working Length= X – 1mm 0,5 -1 mm INGLE’S METHOD • Tooth length is measured in the pre operative radiograph • 1 mm “safety allowance” is subtracted for possible image distortion • the endodontic file is set at this tentative working length, and the instrument is inserted in the canal • on the radiograph the difference between the end of file and root end is measured and this value is either subtracted or added to the initial working length measurement depending on weather the file is short of apex or extended beyond apex • From this adjusted working length 1mm “ safety allowance” is subtracted again to confirm with the apical termination of instrument WEINE’S MODIFICATION A .If, radiographically, there is no resorption of the root end or bone, shorten the length by the standard 1.0 mm. B. If periapical bone resorption is apparent, shorten by 1.5 mm, and C. if both root and bone resorption are apparent, shorten by 2.0 mm ELECTRONIC METHOD OF DETERMINING WORKING LENGTH: ELECTRONIC APEX LOCATORS ELECTRONIC METHOD OF DETERMINING WORKING LENGTH: ELECTRONIC APEX LOCATORS • With a apex locator the working length is determined by comparing the electrical resistance of the periodontal membrane with that of gingiva surrounding the tooth, both of which should be similar • A probe , such as a file, is attached to an electronic instrument with an electric cord and is inserted through the root canal until it contacts the surrounding PDL. • When the probe touches the soft tissues of the PDL, the electrical resistance gauges for both gingiva and PDL would have similar readings. • By measuring the depth of insertion of the probe, you may determine the exact working length of root canal CLASSIFICATION OF APEX LOCATORS • First-generation apex locators based on Resistance • Second-generation apex locators based on Impedance • Third-generation apex locators based on Frequency or comparative impedence • Fourth generation apex locatormeasures resistance and capacitance eparately rather than the resulting impedence FIRST GENERATION APEX LOCATOR • First-generation apex locator devices, also known as resistance apex locators • Measure opposition to the flow of direct current or resistance. • When the tip of the reamer reaches the apex in the canal, the resistance value is 6.5 kilo-ohms (current 40 mA) • often yield inaccurate results in presence of electrolytes, excessive moisture, vital pulp tissue, exudates and blood • Examples: • Neosono apex locator SECOND GENERATION APEX LOCATOR  Second-generation apex locators, also known as impedance apex locators  measure opposition to the flow of alternating current or impedance  Uses the electronic mechanism that the highest impedance is at the apical constriction where impedance changes drastically  Examples  endocater,  sono explorer,  apex finder  endoanalyzer THIRD GENERATION APEX LOCATOR • Works on the principle of frequency or comparative impedence • Examples: • Endex, • Root zx, • Neosono • Ultima Ez, • Mark V plus, MULTIPLE FREQUENCY APEX LOCATORS • Uses two wavelength: one high (8kHz) and one low(400Hz) • They assess the apical terminus by the simultaneous measurements of the impedence of two different frequencies that are used to calculate the quotient of the NEW ADVANCEMENT ELECTRONIC APEX LOCATORS • Integration of the apex locators with the battery powered endodontic slow speed hand piece. • File start to automatically rotate the moment the instruments is introduced in to the canal. • If the preset torque level for the instruments is exceeded then the hand piece automatically stops and reverse rotation. ADVANTAGES OF APEX LOCATOR Devices are mobile, light weight and easy to use Much less time required Additional radiation to the patient can be reduced (particularly useful in cases of pregnancy) 80 - 97 % accuracy observed DISADVANTAGES OF APEX LOCATORS • Accuracy limited to immature root apices • Extensive periapical lesion can give faulty readings • Weak batteries can affect accuracy • Can interfere with functioning of artificial cardiac pacemakers – cuatious use in such patients PAPER POINT METHOD  In a root canal with an immature (wide open) apex, the most reliable means of determining WL is to gently pass the blunt end of a paper point into the canal after profound anesthesia  The moisture or blood on the portion of the paper point that passes beyond the apex - an estimation of WL or the junction between the root apex and the bone. This method, however, may give unreliable data • If the pulp not completely removed • If the tooth – pulpless but a periapical lesion rich in blood supply present • If paper point – left in canal for a long time REFERENCE POINT The reference point is the site on the occlusal or incisal surface from which measurements are made. This point is used throughout canal preparation and obturation. SELECTION A reference point is chosen that is stable and easily visualized during preparation. Usually this is the highest point on the incisal edge on anterior teeth and a buccal cusp tip on posterior teeth. The same reference point is best used for all canals in multirooted teeth. STABILITY • A reference point that will not change during or between appointments is selected. If it is necessary to use an undermined cusp, it should be reduced considerably before access preparation. Areas other than cusp tips, such as marginal ridges or the floor of the chamber, are unreliable or difficult to visualize. • Do not use weakened enamel walls or diagonal lines of fracture as a reference site for length-of-tooth measurement. • Weakened cusps or incisal edges are reduced to a wellsupported tooth structure. • Diagonal surfaces ApeX LOCATOR combination of methods should be used to assess the accurate working length determination Principles:     Outline Form E Resistance Form B Retention Form C Flaring  Outline Form  Resistance Form Retention Form Flaring   Basic preparation throughout its length dictated by the canal anatomy.  Outline Form  Resistance Form  Retention Form Flaring  development of the “apical stop” at the cementodentinal junction Resistance Form  In many cases, the resistance form is positioned average of 0.5 mm in the coronal part of the radiographic apex. However, this distance may increase in elderly patients depending on the construction of cement  Foreman apicale is not always at the apex of the root apical. At least 2/3 of the teeth it has been determined that it is on the lateral surface and specifically determined on the buccal and lingual surfaces of the root. Openings on the buccal and lingual cannot be observed in X-rays. Routine radiographs show only deviations on the proximal surfaces   Outline Form Resistance Form  Retention Form  Flaring to retain the primary filling point; convenience form,subject to revision to accommodate larger,less flexible instruments and to change the external outline form     Outline Form Resistance Form Retention Form Flaring Shaping and cleaning of root canal, from access cavity to resistance form, in a funnel form Recapitulati on Recapitulation refers to the repeated reintroduction and reapplication of instruments previously used throughout the cleaning and shaping process in order to create a welldesigned, smooth, unclogged, evenly tapered, unstepped root canal preparation. Irrigation Before using instruments in the root canal, it should be cleaned of the mass of necrotic, gelatinous material comprised of pulp remnants, bacteria, and tissue fluids. Irrigation should also follow the use of each instrument, and irrigant should then be left in the canal to act as a lubricant for the next instrument. Most instruments cut better in a wet environment than a dry one. STEP-BACK (F.S. WEINE)  The traditional approach to shaping the root canal was to start at the apex and work back up the canal to the crown with increasingly larger instruments, ever widening the canal. This worked well in straight canals.  In curved canals, however, the preparation in the curved apical third often became hour-glass shaped and the apical constriction was destroyed.  The solution, is to clean and shape the canal to the apical constriction with the more flexible files, such as a no. 25, and then step back millimeter by millimeter with increasingly larger, stiffer instruments, for example, from a no. 30 up through a no. 60. This prevents transportation in the apical third.  Although the step-back technique was primarily designed to avoid preparation errors in curved canals, it applies to the preparation of apparently straight canals as well.  All in all the step-back technique has proved very effective, and has led to a decided improvement in the cleaning and shaping, as well as the obturation of root canals. Step-back technique; 1. STEP Apical Stop 2. STEP To prepare a funnel- shaped canal from apical to coronal ‘Initial Apical File’ (IAF) IAF MAF Master Apical File MAF 1 mm shorter than working length MAF at working length MAF 2 mm shorter than working length MAF at working length MAF 3 mm shorter than working length MAF at working length 20 # (IAF) INITIAL APICAL FILE 25 # 19 mm irrigation 30 # 19 mm irrigation 35 # 19 mm (MAF) MASTER APICAL FILE irrigation 40 # 18 mm irrigation 35 # 19 mm irrigation 45 # 17 mm irrigation 35 # 19 mm irrigation 50 # 16 mm irrigation 35 # 19 mm İrrigation REFERENCES 1. Chong B. S 2017 Harty's Endodontics in Clinical Practise 7th Edition Elsevier 2. Torabinajad M., Fouad A.F. Shabahang S. 2021 "Endodontics Principles and Practise" 6 th Edition Elsevier 3. Berman L.H, Hargreaves K. 2021 Cohen's Pathways of the Pulp 12 th Edition Elsevier