Comparative assessment of the long-term effects of 5% sodium fluoride varnishes with and without tricalcium phosphate on enamel microhardness of primary teeth: An in vitro study.

Abstract

Background: Dental caries is among chronic childhood diseases. Fluoride varnish application is a suggested modality, which can reinforce the enamel and decrease the risk of caries. This study aimed to assess the long-term effects of three commercially available fluoride varnishes with and without tricalcium phosphate on the enamel microhardness of primary teeth.

Materials and methods: In this in vitro experimental study, 52 extracted primary molars were randomly assigned to four groups: no fluoride varnish application (control), and treatment with Ariadent, Parla, and Morvabon fluoride varnishes. After specimen preparation and artificial caries induction, the respective fluoride varnish was applied, and the teeth were subjected to remineralization-demineralization cycles at 37°C. The enamel microhardness was measured at baseline, after artificial caries induction, and 24 h and 45 days after the fluoride varnish application. The trend of change in the mean microhardness of the study groups was analyzed by repeated measures ananlysis of variance (alpha = 0.05) and Bonferroni correction. In the next step, the trend of change in microhardness (mean difference) was compared among the groups by the Tukey's HSD test at a 0.05 level of significance.

Results: Enamel microhardness increased during the study period in all groups (P < 0.05), except for the control group. Intergroup comparison of long-term effects revealed that the increase in microhardness in the Parla group was significantly greater than that in the Ariadent (P = 0.01) and Morvabon (P = 0.006) groups.

Conclusion: The results of this in vitro study indicated that application of Parla fluoride varnish, which contains tricalcium phosphate, increased the primary enamel microhardness, and had a more durable effect over time compared with the other two varnishes.