Semester

Fall

Date of Graduation

2019

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Not Listed

Committee Chair

Susan Morgan

Committee Member

Shelia Price

Committee Member

Keith Hildebrand

Abstract

Introduction: Long term success of endodontically treated teeth has been one of the most challenging aspects of the field of endodontics due to reduced fracture resistance of these teeth. Recently, researchers have heightened focus on conservative endodontics in order to sustain the tooth integrity, and reduce factors impacting the fracture resistance of endodontically treated teeth. As a result, rotary instrument manufacturers have developed files that have a minimal effect on original root canal anatomy. This study used Finite Element Analysis to investigate the dental biomechanical effect of rotary instrumentation during root canal therapy. The aim of this study is to compare the effect of three rotary file systems (V-Taper, ProTaper, Vortex Blue) with different tapers on fracture resistance of endodontically treated teeth in the presence of various static and dynamic forces applied to different parts of the coronal part of teeth.

Materials and Methods: In this study, 3D printed acrylic maxillary first molar from Dental Engineering Laboratories LLC DBA DELabs (True Toothä) was used as the prototype of the research model. The original geometry was modified and prepared for using Spaceclaim software for ANSYS modeling and analysis. The three experimental groups and one control group were created. The ANSYS Boolean operations were done in order to generate four different experimental CAD models. Group one was ProTaper, group two was Vortex Blue and group three was V-Taper. Young modulus and Poisson ratio of all the materials (Enamel, Dentin, Gutta-Percha, Composite) were used for ANSYS software to recognize these volumes and the constituents that are contained within these individual spaces. In this study seven total contact points were considered on the occlusal surface of the models during the chewing cycle. The Von Mises stress and maximum principal stress on the cervical region were computed and analyzed in four different cross sections of pre cervical dentin.

Results: The highest Von Mises stress was observed in the ProTaper group although V-Taper and Vortex Blue groups showed homogeneous stress distributions in the cervical regions as well. Tensile stress was concentrated on the palatal side of the palatal root and the distal portion of the distobuccal (DB) root in all the experimental groups. However, the control group had the least amount of stressed area followed by V-Taper group, Vortex Blue and ProTaper.

Conclusion: Taper size of endodontic files appears to be one of many factors which affect the distribution of forces along the root structure. Preserving dental hard tissue in precervical dentin significantly reduces the stress concentration in the cervical region and increases the ultimate fracture resistance of the tooth.

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