Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

Department

College of Dental Medicine

First Advisor

Jeffrey Thompson

Date of original Performance / Presentation

January 2022

Publication Date / Copyright Date

1-1-2022

Abstract

Brief Background: Radiation therapy is used as a part of treatment for head and neck cancer patients. Proton therapy utilizes external beam particle-based radiation. In comparison to photon radiation, it is more localized to the size of the tumor, exposing the healthy tissue with minimal dosing. Research regarding the effect of proton radiation on restorative materials are lacking. Polymethyl methacrylate (PMMA) is commonly used for prosthesis fabrication such as dentures, including the denture base and teeth, obturators, fixed denture prostheses, provisional restorations for crowns, and fixed partial dental prostheses. PMMA has also been used to fabricate occlusal splints and radiation shielding appliances that help to protect tissues from radiation damage. Objective: To evaluate the effect of different intensities of proton radiation on the mechanical and optical properties of heat-cured and milled PMMA. Methodology: A total of 80 PMMA disc specimens were fabricated (40 heat-cured and 40 milled). The specimens were divided into 8 groups, 6 test and 2 control. The 6 test groups were divided according to the proton radiation dose intensities (10 Gy, 30 Gy, and 60 Gy). Specimen gloss and color change were measured. Mechanical testing evaluated flexural strength and microhardness of materials after irradiation. Results: A two-way ANOVA test was conducted to look for differences between the study groups. Proton radiation had a negative effect on PMMA microhardness. Modulus of elasticity was affected by proton radiation. There was no statistically significant effect on the proton radiation effect on flexural strength. Proton radiation did not affect the gloss values of heat-cured PMMA. However, milled PMMA gloss values were affected by radiation. There was no difference in color measured for all groups before and after radiation. Conclusion: Milled PMMA displayed superior mechanical properties when compared to heat-cured PMMA under the impact of proton radiation. Proton radiation had an effect on all the mechanical properties except flexural strength. Proton radiation did not affect the gloss values of heat-cured PMMA. However, milled PMMA gloss values were affected. It can be concluded from the results of this study, that the effect of proton radiation on different types of PMMA used in dental applications is minimal.

Disciplines

Dentistry

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