Student Theses, Dissertations and Capstones

Document Type

Thesis

Degree Name

Doctor of Dental Medicine (DMD)

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

Abraham Lifshitz

Publication Date / Copyright Date

2016

Publisher

Nova Southeastern University

Abstract

Objectives: The purpose of this study was to investigate the association between ligature material and frictional force created during orthodontic cuspid retraction. Maximum static and mean kinetic frictional resistance between conventional metallic orthodontic appliances and esthetic orthodontic appliances will be compared as well. Background: The use of ceramic brackets in conjunction with coated archwires and ligatures as an alternative to conventional stainless steel appliances has increased in response to the demand for more esthetic orthodontic appliances. Esthetic appliances are associated with increased frictional forces and therefore thought to slow the orthodontic treatment. Knowledge of frictional forces generated within various orthodontic appliances is necessary so that appropriate forces can be delivered to achieve clinically desirable rate of tooth movement during sliding mechanics. Frictional forces at the bracket-archwire-ligature interface can affect sliding mechanics. Methods and Materials: In order to measure and compare frictional forces at the bracket-archwire-ligature interface, four maxillary premolar brackets were mounted on a Plexiglass acrylic sheet and one movable bracket was attached to the center of the archwire span. Two types of brackets were used: stainless steel (SS) and ceramic. Brackets used were 0.022 x 0.028 inch slot with RT prescription (DENTSPLY GAC). Tests were performed with 0.017x0.025” SS and 0.017x0.025” Epoxy-coated SS archwires on a Universal Testing Machine (Instron, Grove City, PA) at a crosshead speed of 2.5mm/min, as used by Khamatkar et al2. Archwires were ligated to brackets using 0.010” stainless steel, 0.010” Teflon-coated stainless steel and elastomeric ligatures. The movable bracket was fitted with a 10mm long, 0.045” thick stainless steel arm. A 100gm weight was suspended from the arm to represent the force acting at the center of resistance. Mean kinetic friction was measured for 120 seconds at ten second intervals, beginning at the 30-second time point. Maximum static and kinetic friction measurements were repeated six times and the mean was calculated for each bracket, archwire and ligature combination. Results: Elastomeric ligatures produced more frictional forces than stainless steel ligatures. Teflon-coated coated stainless steel ligatures generated the least amount of frictional resistance. The combination of ceramic bracket, epoxy-coated stainless steel archwire and Teflon-coated stainless steel ligature produced frictional forces that were lower than those by stainless steel bracket, stainless steel archwire and stainless steel ligature. Conclusions: The ligature material used plays a crucial role in the generation of frictional forces at the bracket-archwire interface. Ceramic brackets are comparable to stainless steel brackets in the amount of frictional forces produced. However, the epoxy-coated stainless steel archwires are not as efficient due to the lack of durability of the surface coating.

Disciplines

Dentistry

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