An Sem Investigation Into the Effects of Clinical Use on Heat-Treated Nickel-Titanium Rotary Endodontic Files
Total Page:16
File Type:pdf, Size:1020Kb
AN SEM INVESTIGATION INTO THE EFFECTS OF CLINICAL USE ON HEAT-TREATED NICKEL-TITANIUM ROTARY ENDODONTIC FILES A Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Graduate School of the Ohio State University By Thomas Gerard Burke Jr., D.D.S. Graduate Program in Dentistry The Ohio State University 2016 Master’s Examination Committee: John Nusstein, D.D.S., M.S., Advisor Melissa Drum, D.D.S., M.S. Sara Fowler, D.M.D., M.S. William Brantley, B.S., M.S., PhD John Draper, PhD Copyright by Thomas Gerard Burke Jr., D.D.S. 2016 ABSTRACT Introduction: The third generation of NiTi based rotary files involves a new proprietary thermomechanical process which improves fatigue resistance and flexibility. The purpose of this study was to evaluate the qualitative and quantitative wear/fatigue of three third-generation NiTi rotary endodontic file systems following use in extracted posterior human teeth in a simulated clinical model. Materials and Methods: One hundred files (five packs of five files across four brands: ProFile Vortex™, Vortex Blue™, ProTaper Gold™, and Coltene HyFlex® CM™) were examined with an SEM at the same four positions along their length using a custom-fabricated sample jig before use and through three clinical simulations, and were then evaluated for wear and deformation. Files were categorized as usable, microscopically unacceptable and visually unacceptable. Results: Twelve files visibly failed throughout this study (three separated and eight plastically deformed), and the majority of these failures occurred in the first use of the file. Many instruments were evaluated as microscopically unacceptable before use. A repeated-measures logistic regression analysis found no significant effects for brand, amount of use, and their interaction for files that remained visibly useful. Of those that rated microscopically useful, a significant effect was seen for number of uses (p=0.0127). Contrasts of uses showed significance for use 0 vs. 1, 0 vs. 2, and 0 vs. 3, indicating that unused files were more likely to be microscopically acceptable than used files. No significance was seen between contrasts of uses 1, 2, or 3. Summary and Conclusions: No quantitative wear or distortion pattern specific to any brand was observed that limited multiple file uses. Poor surface condition observed microscopically is not necessarily a precursor to instrument failure. Third-generation controlled memory instruments tend to deform plastically and present minimal risk of clinical separation and canal obstruction through multiple uses. ii DEDICATION To Mom and Dad- for showing me what hard work looks like, how it pays off, and all the fun stuff you get to do when it does. To Kate and Pat- your baby brother is finally done with school. To Erin- I’ll tell you in person, every day. iii ACKNOWLEDGMENTS Dr. Nusstein- I pity the fool that has not had the pleasure of working with you. Dr. Drum- Thanks for talking me into this. Your juggling act amazes me every day. Dr. Fowler- After long hours in predoc, thank you for keeping me calm and allowing me a lunch break every now and then. Dr. Brantley- With how often you appear in my reference section, I could have no better person supporting this project. Dr. Draper- Your willingness to understand dentistry encouraged me to understand statistics. Dr. Reader- You are one of the biggest reasons why I am proud to tell my colleagues where I learned endo. Dr. Beck- I cannot thank you enough for the hours you put into this project, it was a pleasure to have you on board. To Chase, Hannah, and Daniel- There are no other people I would have rather gone through this with. Thank you all! iv VITA September 8, 1987 ...................................................... Born: Parma, Ohio 2006-2009 ................................................................... The Ohio State University Fisher College of Business 2013............................................................................. Doctor of Dental Surgery, The Ohio State University Columbus, Ohio 2016............................................................................. Master of Science & Specialization in Endodontics Post-Doctoral Certificate, The Ohio State University, Columbus, Ohio FIELD OF STUDY Major Field: Dentistry Specialization: Endodontics v TABLE OF CONTENTS Page Abstract ......................................................................................................................... ii Dedication .................................................................................................................... iii Acknowledgements ...................................................................................................... iv Vita .................................................................................................................................v Table of Contents ......................................................................................................... vi List of Tables .............................................................................................................. vii List of Figures ............................................................................................................ viii Chapters: 1. Introduction ........................................................................................1 2. Materials and Methods .....................................................................16 4. Results ..............................................................................................22 5. Discussion ........................................................................................27 6. Summary and Conclusions ..............................................................42 Appendices: A. Tables ..............................................................................................45 B. Figures .............................................................................................60 H. References .......................................................................................81 vi LIST OF TABLES Table Page 1. Visual File Failures (Score of 5) by Brand .........................................................46 2. Individual file failures (Visual failures)..............................................................47 3. File Brand by Canal Curvatures Experienced.....................................................48 4. ProFile Vortex™ Evaluation Summary ..............................................................49 5. ProTaper Gold™ Evaluation Summary ..............................................................50 6. Vortex Blue™ Evaluation Summary ..................................................................51 7. Coltene HyFlex® CM™ Evaluation Summary ...................................................52 8. Visually Unacceptable (Score of 5) Files by Use ...............................................53 9. Microscopically Unacceptable (Score of 4) Files by Use...................................54 10. Clinically Usable (Scores 1-3) Files by Use .......................................................55 11. Regression Results for Visually Acceptable (Scores 1-4) Files .........................56 12. Regression Results for Microscopically Acceptable (Scores 1-3) Files .............57 13. Microscopically Acceptable (Scores 1-3) Regression Contrasts ........................58 14. Microscopically Acceptable (Scores 1-3) Odds Ratios ......................................59 vii LIST OF FIGURES Table Page 1. Unit cells .............................................................................................................61 2. Schematic illustration of atom displacement ......................................................62 3. SEM images of the cross-sectional geometry .....................................................63 4. Austenite to martensite phase transformation .....................................................64 5. Quanta 200 ..........................................................................................................65 6. The custom-made aluminum jig (empty) ............................................................66 7. The custom-made aluminum jig (with files) .......................................................67 8. Evaluation summary by brand and use ...............................................................68 9. Visual file status by brand and number of uses ..................................................69 10. Microscopic file status by brand and number of uses .........................................70 11. The D1 position of a Coltene® HyFlex™ file through each use .........................71 12. A size 25.04 Vortex Blue™ instrument that separated during its first use .........72 13. A size 30.04 Coltene HyFlex® CM™ file that failed by plastic deformation ....73 14. A size S2 ProTaper Gold™ file that failed by plastic deformation ....................74 15. A size 25.04 ProFile Vortex™ instrument that separated during its first use ....75 16. A size 30.04 Vortex Blue™ file experiencing progressive pitting .....................76 17. The size 30.04 Vortex Blue™ after use 3 (surface pitting) ................................77 18. An unused size 30.04 Vortex Blue™ file ...........................................................78 19. An unused size 30.04 ProFile Vortex™ file .......................................................79 20. A size 40.04 Vortex Blue™ file (removal of edge rollover) ..............................80