Date of Award

Spring 2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Ibrahim, Mohamed

Second Advisor

Sidow, Stephanie

Third Advisor

Hashimoto, Lance

Abstract

Introduction: The objective of this study was to investigate the effect of peri-cervical dentin conservation during root canal treatment on the longitudinal propagation of cracks, utilizing the finite element method. Methods: Two 3D printed mandibular molars were subjected to a simulated root canal therapy protocol. The teeth were divided into two test groups: Group 1: Instrumented with using Protaper Gold (PTG) rotary files. Group 2: Instrumented with using TruNatomy. Each access was restored with composite at the level of the CEJ to the occlusal surface. The two teeth were digitized using a high-resolution micro–computed tomographic scan to create 3-D models and stereolithographic reconstructions for Finite Element Analysis. A crack was simulated originating at the distal marginal ridge extending horizontally to the distal occlusal cavosurface, and apically 2mm above the CEJ. Each model was subjected to a 247-newton load to mimic the stress experienced during mastication. Results: In both groups, the crack started propagating at approximately 40,000 mastication cycles. Group 1 which was instrumented with Protaper Gold, had 0.5mm of crack propagation at 60,218,000 mastication cycles. Group 2 which was instrumented with TruNatomy, had 0.5mm of crack propagation at 10,042,000 cycles. Conclusions: Within the limitations of this study, it can be concluded that cracks propagated to a lesser extent in mandibular molars instrumented with PTG compared to TruNatomy. The propagation of the simulated crack for both PTG and TruNatomy initiated around 40,000 mastication cycles.

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