Abstract

The advancement in dental material technology led to the improvement in the fabrication method of PMMA denture bases. Denture base adaptation can be influenced by the amount of polymerization shrinkage that occurs during the processing method of fabrication. CAD/CAM dentures milled from prepolymerized PMMA acrylic resin blocks theoretically have reduced or no polymerization shrinkage. There have been no clinical studies, to date, that have compared retention values between milled and conventionally processed denture bases. Therefore, the purpose of this study clinical study was to compare the retention values between conventional heat polymerized and digital milled maxillary denture bases.

Twenty patients (n=20) with completely edentulous maxillary arches participated in this study. At the first visit, a preliminary impression was made and poured in type III dental stone. A custom tray was constructed from Triad light cure material. At the second visit a heavy body PVS impression material was used to border mold the trays and a final impression was made with light body PVS impression material. The final impression was scanned and the STL files were sent to Global Dental Science for the fabrication of a CAD/CAM milled denture base (AvaDent) (group A). Then the final PVS impression was poured in type III dental stone. The master cast was used to fabricate a heat polymerized acrylic denture base resin (group B). A unique testing device was used to measure denture retention in lbs. The testing device was composed of three parts; DAFG (attached to a motorized test stand), customized FTD and a Panadent earbow ( modified and mounted to a customized wooden stand). The FTD consisted of a hollow brass rod with a pulley at each end used to transfer the force through a nylon thread. A snap hook attachment was attached to the denture base at the center with autopolymerizing resin. The nylon thread was tied securely to the snap hook. At the other end the nylon thread was attached to the DAFG through a secure grip attachment. Each denture base was subjected to a vertical pulling force three times at 10-minute intervals.

The statistical analysis showed significant (α>.05) increase in retention for milled denture base method of fabrication over the conventional polymerizing method with a mean (N) difference of 4.47 lbs (P<0.001). Average retention for the milled denture bases was 16.66 ± 7.32 lbs and average retention for the conventional heat polymerized denture bases was 12.19 ± 6.15 lbs.

Based on analysis of results, it was concluded that the retention of digitally designed and milled complete denture bases from prepolymerized PMMA acrylic resin blocks offer significantly higher retention than the denture bases fabricated by a conventional heat polymerized method.

LLU Discipline

Prosthodontics

Department

Prosthodontics

School

School of Dentistry

First Advisor

Kattadiyil, Mathew T.

Second Advisor

Baba, Nadim Z.

Third Advisor

Goodacre, Charles J.

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2016

Date (Title Page)

3-2016

Language

English

Library of Congress/MESH Subject Headings

Denture Bases; Dental Prosthesis Retention; Dental Stress Analysis; Dental Materials -- Analysis

Subject - Local

CAD/CAM dentures; Pre-polymerized PMMA acrylic resin; Polymerization shrinkage; Dental Material Technology; Fabrication methods

Type

Thesis

Page Count

41

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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