Date of Completion

5-29-2020

Embargo Period

5-28-2020

Advisors

Dr. Robert Kelly, Dr. Kamran Safavi, Dr. Qiang Zhu

Field of Study

Dental Science

Degree

Master of Dental Science

Open Access

Open Access

Abstract

Introduction: The ideal endodontic sealer should be biocompatible, dimensionally stable, and have proper bond strength to dentin. The aim of this study was to apply a hoop stress to sectioned teeth discs which have been obturated with AH Plus sealer with no gutta percha, EndoSequence Bioceramic Sealer (BC Sealer) with no gutta percha, and Tetranite® with no gutta percha until fracture occurred and then compared the failure stresses.

Methods: Teeth were divided into three groups based on the sealer type used. The teeth were sectioned into 2 mm thick discs and load was applied using a piston until fracture took place. The stress generated by the sealer on the dentinal wall was then calculated using a hoop stress formula. One – way ANOVA with a 95% multiple range test was used to compare hoop stresses at failure for all groups (SPSS, TBM). Tukey HSD multiple comparisons test was also implemented to compare values of each group. Linear regression was used to examine failure load versus dentin wall thickness (SigmaPlot 13.0, Systa Software).

Results: Fracture loads forces exerted by the various sealers on the internal tooth wall, demonstrated significant differences amongst all three groups (p < 0.0001). The mean and standard deviation values for failure stress loads were 499.80±120.5555 MPa, 622.3125± 83.7154 MPa, and 708.2357± 68.2772 MPa for the AH Plus sealer with no gutta-percha group, BC sealer with no gutta-percha group, and Tetranite® group respectively. Multiple comparisons showed significant differences between the AH Plus sealer group and BC sealer group (p < 0.002), AH Plus sealer group and Tetranite® group (p < 0.0001), and BC sealer group and Tetranite® group (p < 0.042).

Conclusions: Implementing the hoop stress introduces a novel method for the field of endodontics, of testing sealers and their influence on dentin strength. The current knowledge gap in endodontics lacks a specific method or test application for sealers to potentially enhance dentin strength. The use of piston drive hoop stress test in conjugation with the MTS 858 Mini Bionix® II Biomaterials Testing System is able to provide a method for testing failure stress loads on obturated sectioned teeth. Tetranite® significantly increased fracture stress compared to AH Plus sealer and Endosequence BC sealer. The novel Tetranite group enhanced dentin strength in this study

Major Advisor

Dr. Robert Kelly

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