Effect of Fluoride on Orthodontic Resin Cement Micro-Shear Bond Strength

Objectives: To test the hypothesis that using fluoride would have no effect on mean micro-shear bond strength to enamel.
Methods: Sixty extracted teeth were mounted and polished to a flat enamel surface using 600 grit. The control group [C] received no fluoride treatment prior to the preparation for micro-shear testing. Group [FB] was treated with fluoride toothpaste (available fluoride content <600 ppm), group [FP] was treated with remineralizing tooth gel (sodium monofluorophosphate 900 ppm), and group [FE] was treated with 5% sodium fluoride varnish (22,600 ppm) according to manufacturer's instructions. The teeth were placed in distilled water for 24 hours following treatment. Groups [C], [FB], [FP], and [FE] were prepared for testing using cylinders of orthodontic light-cured resin cement (2 mm in height and 2 mm diameter) were applied to the treated surfaces according to manufacturer's instructions and tested using the UltraTester device.
Results: For micro-shear bond strength, there were no significant difference (p>0.05) between the groups, C 23.98 ±4.96, FB 24.75 ±7.60, FB 26.15 ±6.75 , and FE 19.67 ±7.18 MPa.
Conclusions: Within the limitations of the in vitro study, fluoride application methods did not significantly effect micro-shear bond strength of orthodontic resin cement to enamel surface. The null hypothesis was accepted.