Effect of silver diamine fluoride and potassium iodide pretreatment on microleakage, penetration depth, and color changes of fissure sealants: an in vitro study

BACKGROUND: This in vitro study aimed to evaluate and compare the effects of SDF- and SDF + KI-based pretreatment protocols, with or without NaOCl surface preparation, on microleakage, discoloration, and fissure sealant penetration depth in permanent teeth. METHODS: Sixty extracted mandibular permanent molars with non-cavitated initial enamel lesions (ICDAS score 1) were randomly allocated into six groups (n = 10 per group). According to the experimental design, SDF, SDF + KI, NaOCl surface preparation, and orthophosphoric acid etching protocols were applied before fissure sealant placement. Color measurements were performed using a spectrophotometer according to the CIE Lab* system at baseline (T0) and after all procedures (T1). Microleakage and penetration depth were evaluated using confocal laser scanning microscopy (CLSM). Statistical analyses were performed using the Kruskal-Wallis test and Bonferroni-adjusted pairwise comparisons (α = 0.05). RESULTS: Significant differences were observed among the groups for color change (ΔE) and lightness change (ΔL) (p < 0.001). SDF-treated groups showed significantly higher color change and greater lightness reduction compared with the control group. The mean ΔE values were 6.38 ± 5.42 in the control group, 15.78 ± 2.73 in the SDF group, and 12.60 ± 1.68 in the SDF + KI group. Most ΔE values exceeded the perceptibility (PT = 1.2) and acceptability (AT = 2.7) thresholds. NaOCl application following SDF resulted in significantly higher ΔL values compared with SDF alone. No statistically significant differences were observed among groups for microleakage or penetration depth (p > 0.05). CONCLUSIONS: SDF and SDF + KI pretreatments did not result in statistically significant differences in microleakage or penetration depth under the present experimental conditions, although SDF was associated with clinically relevant discoloration. KI showed only a limited effect in reducing this discoloration. NaOCl application was associated with less unfavorable lightness change in some comparisons; however, this finding should be interpreted cautiously.