Student Theses, Dissertations and Capstones

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Dentistry

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

Chin-yu Lin

Publication Date / Copyright Date

2017

Publisher

Nova Southeastern University

Abstract

Objectives: The objective of this in vitro study is to compare the resistance to sliding (RS) of coated and uncoated orthodontic archwires in ceramic brackets at various water-immersion times and bracket angulations. Background: Tooth-colored orthodontic systems have been developed to meet the patient’s esthetic needs. Ceramic brackets and polymer-coated archwires have been shown to demonstrate higher RS than metal brackets and archwires in dry conditions. However, there is no study to address the RS of coated archwires depending on water-immersion times as in the oral cavity. Therefore, it is necessary to examine RS of coated archwires sliding in ceramic brackets up to 4 weeks of water immersion. Methods: Four groups of 0.019 x 0.025inch stainless-steel archwires: uncoated (group U), Parylene-coated (group P), epoxy-coated (group E), and Teflon-coated (group T) were used. They were immersed for 0 week (T0), 2 weeks (T2), and 4 weeks (T4), in distilled deionized water at 37°C. The RS was measured by sliding the archwires in 0.022inch-slot sapphire ceramic brackets in 0° or 3° bracket angulation. Two general linear models were created to look for differences in RS with Tukey’s HSD for all post-hoc comparisons. The integrity of the archwires was observed under microscope after the sliding test. Results: At 0° bracket angulation, there was no difference in RS between T0, T2, and T4 in groups T & U. In group P, RS at T4 was higher than RS at T0 & T2. In group E, RS at T2 was higher than RS at T0 & T4. At 3° bracket angulation, there was no difference in RS between T0, T2, and T4 in groups P & U. In groups T & E, RS at T4 was highest following RS at T0, and RS at T2 in descending order. All groups showed a higher RS at 3° bracket angulation than RS at 0° bracket angulation in all water immersion times, with exceptions of group T at T2 as no difference was noticed between two bracket angulations, and of group E at T2 as RS at 3° was lower than RS at 0°. Comparing to other groups, group P showed the highest RS in various bracket angulations and water-immersion times. At 0° bracket angulation, group T showed less percentage of coating delamination than the other groups after sliding test. At 3° bracket angulation, all archwires of all groups showed similar coating delamination after sliding test. Conclusions: Resistance to sliding was changed when coated archwires were immersed in water for periods of time. Among the independent variables, surface coating and bracket angulation played a major role in the resistance to sliding.

Disciplines

Dentistry

Keywords

Aesthetic archwire, Coated archwire, Friction, Polymer coating, Resistance to sliding, Water immersion

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