Effect of zinc sulfate on human primary enamel microhardness: an in vitro study.

Objective: The aim of this study was to assess the effect of zinc sulfate on microhardness of human primary enamel.

Method: Sixteen sound primary molars were sectioned mesiodistally. For each sample one of the sections was randomly immersed in artificial saliva (Biotene, USA) and the other was immersed in artificial saliva which was charged with 10 mg/5 mL concentration of zinc sulfate supplement (Razak Company, Iran) daily. After 24 days (the expected time to use up one 120-mL bottle) the surface microhardness of enamel was measured by knoop hardness test (KH) with Knoop diamond under a 50-gram load for 10 seconds.

Results: The mean (+/- SD) microhardness values (KHV) for the tested groups were 320 +/- 49.45 and 357 +/- 36.35, respectively. There were statistically significant differences between the groups as exhibited by independent t-test (P = 0.023).

Conclusion: Primary teeth immersed in a zinc sulfate rich solution for 24 days showed higher microhardness values in comparison with the control group.