Luke K. Choi


The purpose of this study was to determine the effect material and design (slot torque degree and wing type) had on the force and stress to permanently deform metal brackets.

Fourteen different types of metal brackets were tested and categorized into three categories. The three categories were: raw material composition, slot torque degree, and wing type. There were 5 types of raw materials (310SS, 316L, 303SE, 3038, and 17-4PH), 3 types of slot torque degree (0 degree, 7 degree, and 12 degree), and 4 types of wing design (mini twin, single, regular twin, and modified twin). All brackets were tested using arch wire torque test developed by Flores.

An analysis of variance (ANOVA) and Student's t-test showed that raw material, wing type, and slot torque degree had a significant effect on the force and stress to permanently deform metal brackets. Of the three variables, raw material had the greatest effect on the force to permanently deform metal brackets.

Results showed that 17-4PH and 303S had higher yield strengths and regular twin had higher resistance to deformation. Also, as slot torque degree increased, brackets deformed with less force.

A positive correlation between the micro hardness and the stress to deform metal brackets confirmed that brackets with the greatest stress to permanently deform were made of steels with the greatest hardness.

LLU Discipline



Graduate School

First Advisor

Joseph M. Caruso

Second Advisor

Jack L. Tomlinson

Third Advisor

Garland E. Scott

Fourth Advisor

M. Toufic Jeiroundi

Fifth Advisor

Daniel A. Flores

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Dental Stress Analysis; Orthodontic Appliances; Metals



Page Count

iv; 35

Digital Format


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.


Loma Linda University Electronic Theses and Dissertations

Collection Website


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