Effect of Topical Application of Fluoride on the Shear Bond Strength of Fissure Sealant

Statement of Problem: Pit and fissure sealants and topical fluoride are the most important methods to prevent caries in children and adolescents. It was assumed that application of fluoride materials has a negative effect on the bond of adhesive materials such as fissure sealant to teeth. If this is not proved then fluoride therapy can be done before fissure sealant at the same session. The aim of this study was to evaluate the effect of topical fluoride application prior to acid etching on the retention of pit and fissure sealant. In this experimental in vitro study 28 extracted human permanent premolars were used. Each tooth was embedded in dental stone so that the buccal surface was perpendicular to the long axis of the stone block. The teeth were randomly assigned to two groups (n =14). The facial surfaces of all the teeth were freshened by 600 grit silicon carbide paper. The specimens were cleaned with rubber cups and aqueous slurry of pumice, and then rinsed and dried. In the test group, APF gel was applied on the enamel surface and left for four minutes. Then, it was rinsed for 15 seconds. In both groups, etching was done with 37% phosphoric acid for 30 seconds, followed by a water spray wash for 30 seconds and drying for 15 seconds. The fissure sealant, Helioseal F, was then applied to the etched enamel, using a cylindrical plastic tube (3mm × 3mm) perpendicular to the buccal surface. The sealant was cured. The plastic matrix was carefully removed and the specimens were placed in distilled water for 72 hours. Shear bond strength was evaluated, using a universal testing machine. A shear force was applied to the tooth at a cross-head speed of 1 mm/min. Data were analyzed with Mann-Whitney test. The mean shear bond strength was 17.7±5.28 for the control and 19.66±4.27 Mpa for the test group. There was no statistically significant difference in the shear bond strengths between the two groups (p >0.05). The results of this study showed that application of fluoride does not affect the shear bond strength of fissure sealant to the enamel.