Title
The Influence of Peri-Cervical Dentin Conservation on the Propagation of Cracks in Mandibular Molars
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.