Performance of enamel after varnish application under simulated erosive conditions

Preventive efforts and early diagnosis of erosive tooth wear (ETW) are essential to minimize damage to dental hard tissues. In addition to controlling etiological factors, the synergistic action of specific agents can help maintain oral health. This study aimed to evaluate the ability of bioactive varnishes to prevent and/or control the progression of ETW on enamel.

A total of 120 bovine enamel blocks (n = 5 per subgroup) were randomly allocated into three initial enamel condition groups: sound (S), extrinsically eroded (EE; subjected to orange juice for 1 min, 3×/day, over 5 days), and intrinsically eroded (IE; exposed to 0.01 M hydrochloric acid for 2 min, 4×/day, over 5 days). Each group was subsequently subdivided according to the treatment received: Duraphat (D) - fluoride varnish; Clinpro (C) - tricalcium phosphate-modified formula; and PRG Barrier Coat (B) - containing S-PRG particles. Surface microhardness (SM) (KHN, 25 g/10 s/5×) and wettability (W) were assessed at three time points: I - after the first erosive challenge, AA - after varnish application, and F - after the second erosive challenge. Data were analyzed using normality tests, three-way repeated measures ANOVA, and Tukey's test (α = 0.05).

Both erosive protocols reduced SM compared to the sound group. After the second challenge, all varnishes preserved SM, indicating protective effects. For wettability, intrinsic eroded group showed the lowest values, while varnish PRG Barrier Coat showed the highest.

Bioactive varnishes act as protective barriers against acidic challenges, and their distinct compositions may contribute to the prevention of enamel erosion progression.

Bioactive varnishes contribute to enamel protection by preserving surface hardness under both intrinsic and extrinsic acid exposure.