Abstract

Since virtually all stages of orthodontic treatment involve forces obtained from deformed metallic materials, an understanding of properties of metals is an important part of orthodontics. The use of chromium-cobalt alloy for arch wires is relatively new to the field, and more needs to be known about its use in order to get the most from this product.

Many clinicians feel that advantages can be gained through a low temperature heat-treatment to change certain mechanical properties of the material. A tensile test was chosen in the attempt to learn more about this alloy in the untreated form as well as the changes that can be brought about by various heat-treatments.

Chromium-cobalt wires from the same batch of the size .016 X .022 inches were tested for mechanical property changes when heat treated for 5 minutes in an oven at temperatures ranging from 600°F to 1400°F or with flash paste at 950°F. The treated wires were compared with untreated ones by the tensile test on a Riehle FS-5 machine. The wires were stretched until fracture occurred and calculations were made for modulus of elasticity, tensile strength, yield strength and percent elongation.

Modulus of elasticity increased by 8 percent, tensile strength increased by 17 percent, and yield strength increased by 43 percent for wires oven treated 5 minutes at 1000°F compared to the untreated. Percent elongation decreased by 22 percent when the same comparisons were made.

Significant mechanical property changes can be made in chromium cobalt alloy wire with heat-treatment. The properties that can be measured by the tensile test can be related directly to stiffness, strength and range.

The greatest benefit to orthodontics would be the increase in working range caused by the large increase in yield strength.

LLU Discipline

Orthodontics

Department

Dentistry

School

Graduate School

First Advisor

John L. Tomlinson

Second Advisor

John K. Pearson

Third Advisor

Lawrence W. Will

Fourth Advisor

Clelan G. Ehrler

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1978

Date (Title Page)

6-1978

Language

English

Library of Congress/MESH Subject Headings

Orthodontic Appliances

Type

Thesis

Page Count

vi; 28

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

Download

Share

COinS