Effect of a Propolis/Chitosan Varnish on Demineralized Primary Tooth Enamel: An In Vitro Study

Background: Natural compounds such as propolis and chitosan have been investigated for their potential use in dental formulations. Aim: To evaluate the effect of an experimental propolis/chitosan varnish on previously demineralized primary tooth enamel using surface roughness, wear profile, microhardness, and morphological analysis. Design: Primary enamel specimens were allocated to three groups (n = 13): no treatment control (C), Duraphat varnish (DV), and experimental propolis/chitosan varnish (EV). Specimens were first subjected to a demineralizing challenge to produce artificial caries-like lesions. After treatment application, samples underwent seven days of pH cycling. Surface roughness, wear profile, and longitudinal Knoop microhardness were evaluated. Data were analyzed using ANOVA and Tukey’s post hoc test (α = 5%). Results: For wear profile, no significant differences among groups were observed after initial demineralization or after treatment/pH cycling. Post-treatment roughness differed among groups, with DV showing the highest Sa values, whereas C and EV were statistically similar. For microhardness, DV showed the highest EA/DA and EA/CA percentage values and differed significantly from C and EV. The EV group did not differ significantly from the untreated control for wear profile or microhardness. Morphological analysis showed surface irregularities after demineralization and different surface patterns after treatment. Conclusions: Under the conditions of this in vitro study, the experimental propolis/chitosan varnish did not promote remineralization of previously demineralized primary enamel and did not demonstrate superiority over the untreated control. Duraphat varnish showed microhardness values suggestive of partial mineral recovery.