College of Dental Medicine Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

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

Publication Date / Copyright Date

2013

Publisher

Nova Southeastern University

Abstract

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry.

Objectives: To date, the literature has shown that a 10 second curing time is necessary to consistently achieve effective shear bond strengths (SBS) of greater than 10 MPa. Recently, several manufacturers have developed high power curing lights that claim only a 6 second cure time is needed. The purpose of this study was to evaluate the shear bond strength of orthodontic brackets when using two new high power LED curing lights after a 6 and 12 second light curing time. Methods: 120 extracted premolars were divided into 6 groups (n=20). Metallic brackets were bonded using Transbond XT (3M-Unitek) and cured for 6 or 12 seconds using two high power LED curing lights (Ortholux Luminous LED, 3M-Unitek; OrthoValo, Ultradent) and one control LED unit (Ortholux LED, 3M-Unitek). The samples were stored in distilled water for 24 hours at 37°C, thermocycled and then debonded using an Instron Universal Testing Machine at a crosshead speed of 5mm/min. Bond failure was evaluated under optical microscopy using a modified adhesive remnant index (ARI). Results: All sample groups produced mean SBS higher than 10MPa. Significant reductions in SBS were observed with the Ortholux LED when the curing time was reduced from 12 to 6 seconds. The OrthoValo had significantly higher SBS than the Ortholux LED and the Ortholux Luminous LED at 6 seconds. At 12 seconds, OrthoValo SBS were significantly higher than Ortholux LED only. A higher frequency of enamel damage occurred in the OrthoValo group (28.2%) compared to the Ortholux LED (12.5%) and Ortholux Luminous LED (7.5%). No significant correlation was found between ARI score and SBS. Conclusions: Higher SBS were obtained in the OrthoValo group. This coincided with a higher frequency of enamel damage.

Disciplines

Dentistry | Orthodontics and Orthodontology

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