Evaluation of the Paper Point Technique for Locating the Root Canal Apical Exit Jose Luis Marcos -Arenal A thesis submitted to the faculty of the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Master of Science in the School of Dentistry (Endodontics) Chapel Hill 2007 Approved by: Dr Martin Trope Dr Eric M Rivera Dr Daniel J Caplan ABSTRACT Jose Luis Marcos -Arenal: Evaluation of the Paper Point Technique for Locating the Root Canal Apical Exit (under the direction of Drs Martin Trope, Eric M Rivera and Daniel J Caplan) A new method for determining root canal working length ( WL ), the paper point technique (PPT) , has been claimed to be accurate and reproducible , but has not been formally evaluated. Hypothesi s: WL determination is more accurate when the Electronic Apex Locator Technique (EALT) is supplemented with PPT compared to EALT alone . The lengths of 84 root canals of unsalvageable human teeth were measured first using EAL T, then PPT. Endodontic files were cemented to the position indicated by PPT . The teeth were extracted and microCT - scanned . In 71 canals that provided adequate readings for both EAL T and PPT , the RCAE to file tip distance was measured to 20 µm resolution . Both techniq ues showed (1) moderate agreement and (2) excellent repeatab ilities . There was (3) a significantly greater accuracy in locating the RCAE when PPT was used compared to EALT alone (p ≤0.0 051 ). Conclusion: It may be advisable to supplement the EALT measurement with PPT. ii dedicated to the dentists of the Future iii ACKNOWLEDGEMENTS Dr T ro pe , Dr Rivera and Dr Caplan , you support ed me throughout this project and were patient with my innumerable questions . Every one of the pati ent patient s who participated in the study . And t he students and Admissions Desk staff (Sh irley †, Cynthia, Monty and Jean ) wh o referred them to us . Wallace Ambrose taught me how to use the m icro -CT machine . Hyuns oon , Lin and Dr G Koch from the UNC Biometric Co nsulting Lab oratory analyzed our data expecting no thing in return . The UNC Department of Endod ontic provided funds and premises for this project. Thank you. I will never forget it. JLM A iv TABLE OF CONTENTS LIST OF TABLES ................................ ................................ ................................ ................................ ......... viii LIST OF ILLUSTRATIONS ................................ ................................ ................................ ............................. ix LIST OF ABBREVIATIONS ................................ ................................ ................................ ............................. x CHAPTER 1: INTRODUCTION ................................ ................................ ................................ ................ 1 CHAPTER 2: REVIEW OF THE LITERATURE ................................ ................................ ........................ 3 2.1 APICAL THIRD OF A ROOT ................................ ................................ ................................ ....... 3 2.1.1 Anatomy and Histology ................................ ................................ ................................ .. 3 2.1.1.1 Of the tooth hard tissues ................................ ................................ ........................ 3 2.1.1.2 Of the tooth soft tissues: the dental pulp ................................ ............................... 6 2.1.1.3 Of the periodontal tissue surrounding the root canal exit. ................................ ...... 7 2.1.2 Physiology & Pathology ................................ ................................ ................................ .7 2.2 WORKING LENGTH DE TERMINATION IN ENDODONTICS ................................ ..................... 8 2.2.1 Definition ................................ ................................ ................................ ........................ 8 2.2.2 The importance of a correct WL determination. ................................ ............................. 8 2.2.2.1 Biological reasons ................................ ................................ ................................ .8 2.2.2.2 Philosophical Reasons. ................................ ................................ ......................... 9 2.2.3 The apical reference p oint in WL determination. ................................ ........................... 9 2.2.4 Methods to determine WL: description, degree of accuracy and shortcomings ........... 11 2.2.4.1 Periodont al sensitivity/Patient response. ................................ ............................. 11 2.2.4.2 Tactile Method. ................................ ................................ ................................ .... 12 2.2.4.3 Radiographic ................................ ................................ ................................ ....... 12 2.2.4.4 Electronic ................................ ................................ ................................ ............. 16 2.2.4.5 Combined use of EAL and radiographs ................................ ............................... 20 2.2.4.6 New method: the Paper Point Technique ................................ ............................ 20 2.3 MICRO COMPUTED TOMOGRAPHY (CT) IN EXPERIMENTAL ENDODONTICS .................. 22 2.3.1 Introduction ................................ ................................ ................................ .................. 22 2.3.2 Resolution of micro -CT (for measurement of teeth length). ................................ ......... 22 2.3.3 Limitations of micro -CT. ................................ ................................ ............................... 23 v CHAPTER 3: MANUSCRIPT ................................ ................................ ................................ .................. 25 3.1 INTRODUCTION, LITERATURE REVIEW and RATIONALE for this PROJECT ...................... 25 3.2 HYPOTHESIS ................................ ................................ ................................ ............................ 27 3.3 PURPOSE and SPECIFIC AIMS ................................ ................................ ............................... 27 3.4 MATERIALS and METHODS ................................ ................................ ................................ ..... 28 3.4.1 Overview of design. ................................ ................................ ................................ ..... 28 3.4.2 Subjects and Teeth ................................ ................................ ................................ ...... 28 3.4.2.1 Inclusion/exclusion criteria ................................ ................................ ................... 28 3.4.2.2 Collected data ................................ ................................ ................................ ...... 29 3.4.2.3 Sample size calculation: ................................ ................................ ...................... 29 3.4.3 In vivo part of the study: ................................ ................................ ............................... 30 3.4.3.1 Assessment of patients and teeth ................................ ................................ ........ 30 3.4.3.2 Anesthesia, operating field isolation and tooth decoronation ............................... 30 3.4.3.3 Obtaining the EAL -length ................................ ................................ ..................... 31 3.4.3.4 Obtaining the PPT -length ................................ ................................ .................... 32 3.4.3.5 Cementing an endodontic instrument to PPT -length ................................ ........... 35 3.4.3.6 Tooth extraction ................................ ................................ ................................ ... 35 3.4.4 Ex vivo part of the study. ................................ ................................ ............................. 35 3.4.4.1 Specimen preparation and storage ................................ ................................ ...... 35 3.4.4.2 Micro -CT image acquisition ................................ ................................ ................. 36 3.4.4.3 Volumetric reconstruction of the tooth apex ................................ ......................... 38 3.4.4.4 Analysis of reconstructed apices: measuring the file -tip to RCAE distance ......... 38 3.4.4.5 Observations and Measurements ................................ ................................ ........ 39 3.4.5 Data Analysis ................................ ................................ ................................ ............... 40 3.4.5.1 Definition of Variables ................................ ................................ .......................... 40 3.4.5.2 Analysis of the data ................................ ................................ ............................. 40 3.4.5.3 Reliability of the Image Analysis. ................................ ................................ ......... 41 3.5 RESULTS ................................ ................................ ................................ ................................ .. 42 3.5.1 Accuracy (n=71): ................................ ................................ ................................ ......... 43 3.5.2 Repeatability (n=9): ................................ ................................ ................................ ..... 46 3.5.3 Agreement (n=71): ...............................