Date of Award



Department of Endodontics

First Advisor

Ove Peters, DMD, MS, PHD

First Committee Member

Christine Peters, DMD

Second Committee Member

Craig Dunlap, DDS


Aims Preservation of peri-cervical dentin during the preparation of endodontic access is important to prevent fractures and improve the long-term prognosis. The purpose of this study was to evaluate the impact of rotary file instrumentation (TruNatomy and XP-Endo Shaper) on peri-cervical dentin removal, depending on access size. Materials and Methods Forty 3D printed mandibular first molars, with either a small or large access design, were instrumented using TruNatomy or XP-endo Shaper file systems. Canal volumes were calculated based on micro-computed tomography data obtained pre- and post-operatively. Digital sectioning of each reconstructed volume was performed 90-degrees to the long axis at the floor of the pulp chamber at 5 levels, at the pulp chamber floor (Level 0) as well as 1 and 2mm coronally and apically of Level 0. Linear measurements were taken from the inner wall of the access cavity or canal to the outer surface of the tooth for both instrumentation techniques and compared to the unprepared control dataset. These measurements served as an approximation of remaining peri-cervical dentin after root canal instrumentation. Results Some of the coronal measurements were not reportable for the control group due to incomplete capture of the crown during the microCT scan. The remaining peri-cervical dentin thickness at the level of the pulpal floor and coronally were significantly (p<0.01) affected by the access cavity size, with the smaller access preserving more dentin in all samples. Apical to the pulpal floor, there was no significant difference between instrumentation groups at the data points evaluated. Remaining dentin thickness was largest at coronal section 1 and smallest at apical section 6 with 3.81mm (p = 0.05) and 1.84mm (p = 0.06), respectively. Conclusion Access cavity size had a significant impact on remaining dentin thickness at the level of the pulpal floor and coronally, with more remaining dentin in the conservative access group, irrespective of instrumentation technique. Future studies will evaluate dentin thickness in the furcation and mid root level, as well as apical canal transportation, and procedural errors.