Effect of Fluoride Application on Enamel Surface Micro-Hardness

Objectives: To test the hypothesis that fluoride treatment would not have a significant effect on enamel surface micro-hardness.
Methods:
Sixty extracted teeth were mounted, and polished to a flat enamel surface using 600 grit. 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 [FB], [FP], [FE] were tested using Vickers Hardness test device (1000 g load) both before and after the assigned treatments.
Results: For surface enamel micro-hardness there was a significant difference (p<0.05) between the groups, [C] 338.92 ±26.71, [FB] 284.01 ±62.72, [FP] 303.50 ±16.68, and [FE] 276.74 ±29.74 HV1.0. However, there was no significant difference (p>0.05) between the groups [FB], [FP] and [FE].
Conclusions: Within the limitations of the in vitro study, fluoride application methods did significantly effect the enamel surface microhardness. The null hypothesis was rejected.