EFFECTS OF FLUORIDE APPLICATION ON SHEAR BOND STRENGTH OF ORTHODONTICBRACKETS

The purpose of this study was to determine the shear bond strength and debonding failure modes of orthodontic brackets bonded to teeth that have been treated with various fluoride concentrations. Thirty-six rec ently extracted human premolars were divided into three groups: prophy laxis with pumice only, prophylaxis using a 13,500 ppm fluoridated pum ice, and prophylaxis with pumice followed by application of a 2500 ppm fluoridated paste. The teeth were etched with a 37% phosphoric acid g el, then bonded with a metal orthodontic bracket. The teeth were mount ed in phenolic rings and stored in de-ionized water at 37 degrees C fo r 72 hours. A Zwick Universal Testing Machine was used to determine sh ear bond strengths. The residual adhesive on the enamel surface was es timated using the Adhesive Remnant Index. Analysis of variance was use d to compare the various groups, and significance was predetermined. a t p less than or equal to.05. The results indicate that there were no significant differences in bond strengths between the treated and untr eated teeth (p=.233). The Chi Square test evaluating the residual adhe sive on the enamel surfaces also showed no significant differences (p= .456). In conclusion, the use of fluoridated prophylactic pastes with varying fluoride concentrations does not significantly affect shear bo nd strength or bond failure location.