The susceptibility of stained-remineralized caries lesions to restaining and bleaching after microabrasion, bleaching and resin infiltration.

PURPOSE: To investigate the susceptibility of stained-remineralized caries lesions (s-RCLs) to restaining and bleaching after treatment with microabrasion, at-home bleaching (AHB), and resin infiltration (RI). METHODS: Enamel specimens were demineralized then randomized into seven groups (n = 12). G1; control, G2; RI, G3; s-RCLs, and G4; s-RCLs + AHB (15% carbamide peroxide, 4 h/d × 7); G5; s-RCLs + microabrasion (6.6% hydrochloric acid, 1 min/3 cycles) +AHB; G6; s-RCLs +AHB+ RI; G7: s-RCLs + microabrasion + AHB + RI. Subsequently, groups were restained, then bleached. Color and gloss were analyzed using ANOVA and Tukey's test (α = 0.05). RESULTS: Restaining reduced lightness, significantly affecting G1, G3, G5, and G7 (P ≤ 0.028). Control groups exhibited the highest susceptibility, then G7 and G4. G5 had the least restain, without exceeding the original treatment value. Bleaching increased lightness, notably in G1-G3 (P ≤ 0.011). G1 and G5 eliminated restaining, while G7 demonstrated near-complete discoloration reversal. Gloss decreased after staining (P ≤ 0.03) (except G3, G5) and improved post-bleaching (P ≤ 0.025). RI groups maintained the highest gloss, while G4 had the lowest. CONCLUSION: Microabrasion and bleaching demonstrated the lowest restaining and complete stain elimination with color and gloss improvements post-bleaching, suggesting that microabrasion may represent a valuable step in enhancing the optical outcome of s-RCLs.