Abstract

The purpose of this study was to investigate the plastic (permanent) deformation of a polycarbonate bracket (Miura, RMO) under the following different conditions: (1) untreated, (2) immersed in 37°C-water for 120 days, and (3) immersed in 60°C-water for 24 hours. Ten brackets for each condition were tested, with a total of 30 brackets tested. Each bracket was bonded to a metal mesh pad which was tack welded to a solid stainless steel ring. The assembly was placed under a loading frame. This loading frame removes variables such as bond adhesive strengths, distortion of a wire used to deform the bracket slot, and strength added to the slot by ligature tie wires. The bracket slot was loaded by application of a biaxial load in order to produce a wedging force to deform the wings of the bracket. The bracket slot was placed in this loading frame for five hours using 2,000 gm of force. The bracket slot width was measured before being loaded, immediately after five hours of loading, and 24 hours after being released from the load.

There was a statistically significant difference in the plastic deformation of each treatment group from the preloaded brackets to the loaded brackets and 24 hours after being released from the load. However, there is no statistically significant difference in the amount of plastic deformation between different treatments.

LLU Discipline

Orthodontics

Department

Orthodontics and Dentofacial Orthopedics

School

Graduate School

First Advisor

M. Toufic Jeiroudi

Second Advisor

Daniel A. Flores

Third Advisor

Anthony H. L. Tjan

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1995

Date (Title Page)

6-1995

Language

English

Library of Congress/MESH Subject Headings

Orthodontic Appliances; Dental Bonding

Type

Thesis

Page Count

2; vi; 17

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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