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.
Key Words: Deciduous, dental caries, dental enamel, hardness tests, primary prevention, tooth

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