Scanning Electron Microscopic Study of Shear Bond Strength with Acidulated Phosphate Fluoride Applied before Acid Etching

Introduction: The topical fluoride is effective in increasing resistance to dental caries or enamel decalcification. Acidulated phosphate fluoride increased the uptake of fluoride by the enamel at rates higher than either stannous fluoride or neutral sodium fluoride The fluoride deposits in hydroxyapatite to form fluorapatite. However the fluorapatite may affect the bond strength or debonded interface this study is to evaluate the shear bond strength with acidulated phosphate fluoride before acid etching and detect the changes on the enamel surface after debonding with the fluoride application before acid etching with scanning electron microscope. Materials and Methods: Forty human premolar teeth were extracted from teenagers (9 to 16 years of age). The teeth were randomly divided into two groups of 20 teeth each for evaluating shear strength. The specimens of Group 1 (Control Group) the etchant solution was applied on the buccal surface of each crown for 15 seconds then rinsed with an abundant spray of water for 10 seconds and dried with an air spray In the group 2 the teeth were immersed in APF gel (Vishal Pharma Ahmedabad) for 4 minutes. The treated teeth were removed from the APF gel and left untouched for 30 minutes. Subsequently the gel was washed off with a 1 minute water spray. The enamel of each tooth was etched for 15 seconds with acid solution for bonding. The buccal surfaces of the teeth were abundantly washed with a water spray for 10seconds then dried again etched enamel and bracket base were coated with a sealant and the composite resins (3M Unitek Co, USA) immediately applied to the bracket base. Results: The Mean shear strength of control group (Group I) 10.76 MPa Group II (APF application before acid etching 10.55 MPa In the SEM study APF gel produced surface coating appeared to consist of a uniformly thick layer of densely packed small globular particles present before acid etching. Conclusion: There is no statistically significant difference in bond strength with the APF application before acid etching compared to the control group.