Date of Award

Spring 1992

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Dhuru, Virendra B.

Second Advisor

Ferguson, Donald J.

Third Advisor

Kittleson, Russell T.

Abstract

The acid-etch technique is presently the most widely accepted procedure for preconditioning the tooth enamel for bonding orthodontic brackets. This technique is fraught with a number of problems that can affect the strength of the adhesive bond between the bracket and the tooth. An alternative method for etching enamel is to use a carbon dioxide (CO2) laser for etching rather than acid. Preliminary research indicates that CO2 laser etching may provide a rougher and more consistently etched surface than acid etching. Bond studies are necessary to evaluate the efficacy of using this technique for etching and providing clinically acceptable bond strengths without harming the tooth. This investigation was designed to evaluate and compare the tensile bond strengths of orthodontic brackets attached to teeth treated with acid etching and carbon dioxide lasing. One hundred and thirty bovine mandibular incisors were assigned to one of thirteen treatment groups. Three additional incisors were selected for examination by scanning electron microscopy after treatment. The teeth were pumiced, rinsed and dried. They were then either acid-etched according to the manufacturer's recommendations or laser-etched at various predetermined parameters. All teeth were bonded, except those chosen for SEM examination, and were stored in 37°C distilled water for 48 hours prior to testing. A custom fabricated alignment apparatus and an Instron testing machine were utilized to apply a tensile force. The force needed to induce bond failure was recorded and the site of bond failure evaluated under a stereo microscope...

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