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 2021

Publication Date / Copyright Date

1-1-2021

Abstract

Abstract Background: The use of a full arch fixed complete denture is considered an evidence-based therapy for the treatment of edentulism that has revolutionized the field of prosthodontics. Both the temporary screw retained complete denture and final prosthesis can be made from Poly methyl methacrylate (PMMA). Advances in the fabrication methods of full arch fixed complete dentures could reduce the clinical and laboratory time as well as the cost needed to fabricate such prosthesis. Recently introduced methods include additive (3D printing) or subtractive (milling) procedures, which offer superior physical and esthetic characteristics and can be more hygienic to the patient. Specific Aims: The purpose of this in vitro study was to compare the material properties of conventionally processed PMMA, milled PMMA, and 3D-printed PMMA in terms of esthetic characteristics and physical/mechanical properties, after hydrothermal aging. Physical/mechanical properties include flexural strength and Vickers hardness, and characterization of mode of fracture. Esthetic characteristics include color stability and gloss retention. These data were used to estimate the likely clinical and esthetic behavior of the tested materials. Significance: Comparisons of the material behavior of conventionally processed, milled, and 3D-printed full arch fixed complete dentures are scarce, complicating informed decisions on material choice. Innovation: This in vitro study provides some insight about how PMMA prosthetics fabricated by three different processing methods are affected by hydrothermal aging. A review of the scientific literature (2021) indicates that studies comparing these materials are scarce. Methodology: In vitro laboratory testing compared 3D-printed, milled, and conventionally processed PMMA hybrid prosthesis analogs (bars, 2 X 2 X 25 mm). A total of three main groups were prepared (n = 20/group). Half of the specimens of each group underwent thermocycling (hydrothermal aging). The rest of the specimens served as a control group. After aging, flexural strength, Vickers hardness, and mode of fracture behavior were assessed. For the second part of this study, thirty (n = 10/group) square shaped specimens (15 X 15 X 2 mm) were made using the same processing techniques, and color stability and gloss retention tests were conducted. Results: Flexural strength and hardness results showed no significant difference following hydrothermal aging. Milled samples displayed significantly lower flexural strength values due to sample preparation methodology. Irrespective of the processing method, the acrylic resins showed a high degree of brittleness. If the standard of ΔE < 3.3 as clinically acceptable was taken into consideration, each processing method resulted in acceptable shade shift (of ΔE < 3.3) after hydrothermal aging. There was no significant difference in gloss retention of PMMA specimens produced by different processing methods following hydrothermal aging. Conclusion: Within the limitations of this study, it was observed that thermocycling has no statistically significant influence on the mechanical and physical behavior of 3D-printed and milled PMMA. Acrylic resins exhibited a high number of brittle fractures, irrespective of the processing technique and artificial aging.

Disciplines

Dentistry

Download

Download Full Text (1.8 MB)

Download
To access this thesis/dissertation you must have a valid nova.edu OR mynsu.nova.edu email address and create an account for NSUWorks.

Free My Thesis

If you are the author of this work and would like to grant permission to make it openly accessible to all, please click the Free My Thesis button.

  Contact Author

Share

 
COinS