Date of Award

Spring 2006

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Berzins, David W.

Second Advisor

Bradley, Thomas G.

Third Advisor

Liu, Dawei

Abstract

Bond failure of brackets is a problem to the practicing orthodontist. The occurrence of these failures can not only be frustrating for the practitioner but can significantly effect treatment efficiency. Bracket failure causes lengthy appointments which can have an economic impact on a practice. Often, the wire has to be changed and the progress of the treatment can be significantly delayed. One reason for this occurrence, and the focus of this study, can be the differing bond strength of the adhesives used in addition to the type of orthodontic brackets to which the adhesive is placed. The purpose of this study was to evaluate and compare the shear bond strengths of two adhesives using two types of brackets; a conventional and a self-ligating bracket system. Sixty extracted human premolars were collected. The premolars were randomly divided into three groups of twenty teeth. All three groups were direct bonded. Groups 1 and 2 used light-cured adhesive and primer (Transbond XT) with a conventional (Orthos) and a self-ligating bracket (Damon 2), respectively. Group 3 used a light-cured primer (Orthosolo) and a light-cured adhesive 1(Blugloo) with a self-ligating bracket. The specimens were stored in distilled water at 37°C for 40 ± 2 hrs, after which they were debonded and inspected for Adhesive Remnant Index (ARI) scoring. The mean shear bond strength of groups I, 2, and 3 were 15.20, 23.18, and 24.80 MPa, respectively. A one-way analysis: of variance and post hoc Tukey test showed significant differences in bond strength (p<0.001) between group 1 and groups 2 and 3, but no significant difference (p>0.05) between groups 2 and 3. A Weibull analysis demonstrated that all three groups provided sufficient bond strength with over 90% survival rate at normal masticatory and orthodontic force levels. A Kruskal-Wallis test showed no significant difference (p>0.05) in ARI scores between all three groups. All three groups demonstrated clinically acceptable bond strength. The Damon 2 self-ligating bracket exhibited satisfactory in vitro bond strength with both adhesive systems used.

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