The combined remineralizing effect of Er: YAG laser, fluoride varnish and CPP-ACP.

This study evaluated the remineralization efficacy of Er: YAG laser, CPP-ACP, and 5% NaF varnish, used individually or in combination. Seventy extracted permanent third molars were used. Early enamel lesions were induced on the buccal surfaces via demineralization, followed by one of the following treatments (n = 10 per group): (1) MI Paste (CPP-ACP, GC, Japan) for 5 days, 3 min daily; (2) 5% NaF varnish (Master-dent, USA) for 1 min; (3) Er: YAG laser irradiation (Pluser, LAMBDA S.p.A., Italy; 2940 nm wavelength, 80 mJ energy, 5 Hz frequency, 2 mm distance, 10 s); (4) MI Paste + 5% NaF varnish; (5) 5% NaF varnish + laser irradiation; (6) MI Paste + laser irradiation; or (7) MI Paste + 5% NaF varnish + laser irradiation. Surface microhardness was measured at baseline, after demineralization, and after remineralization. Surface morphology was examined using field emission scanning electron microscopy (FESEM). Data were analyzed using two-way ANOVA, Welch's one-way ANOVA, and Games-Howell and Tukey HSD post-hoc tests (P < 0.05). Results indicated that the three-component treatment showed the highest ΔREM-DEM values at all measured depths (P < 0.001). FESEM confirmed that this group exhibited the most uniform enamel surface with densely packed mineral deposition. At 60 μm, two-component treatments showed statistically similarmicrohardness gain, yet each significantly higher than the single-agent groups (P < 0.001). At 100 μm, groups 4 and 6, as well as groups 4 and 5, demonstrated comparable outcomes, while all other pairwise comparisons remained significantly different (P < 0.001). In conclusion, in this in vitro model, the combination of CPP-ACP, 5% NaF varnish, and Er: YAG laser irradiation produced the greatest improvement in enamel microhardness in initial carious lesions.