Comparison of the effect of self-assembling peptide P11-4 on post-bleaching shade stability and microhardness with different bioactive remineralization agents.

BACKGROUND: This in vitro study aimed to evaluate and compare the efficacy of six remineralization protocols—including a self-assembling peptide (SAP) P11-4 (Curodont™ Protect), a surface pre-reacted glass-ionomer agent (PRG Pro-Care Gel), nano-hydroxyapatite (Apa Care Repair), casein phosphopeptide-amorphous calcium phosphate (Tooth Mousse), fluoride (ReminPro), and a control—on enamel microhardness recovery and color stability following in-office bleaching with 35% hydrogen peroxide. MATERIALS AND METHODS: Thirty caries-free premolars were sectioned to obtain enamel specimens. Baseline (T0) color (CIEDE2000) and microhardness (Vickers, 300 g/15s) were measured. All samples underwent a standardized bleaching protocol (three 8-minute cycles, total 24 min). Post-bleaching measurements (T1) were taken. Specimens were randomly assigned to six groups (n = 5): Control (artificial saliva), ReminPro, Tooth Mousse, Apa Care Repair, PRG Pro-Care Gel, and Curodont™ Protect. Remineralization agents were applied four times over 28 days. Final measurements (T2) were taken after 28 days in artificial saliva. Data were analyzed using Two-Way Repeated Measures ANOVA with Bonferroni post-hoc tests (α = 0.05). RESULTS: Bleaching significantly reduced enamel microhardness in all groups (p < 0.001). After 28 days, all agents promoted microhardness recovery compared to control (p < 0.001). Curodont™ Protect achieved microhardness values statistically equivalent to baseline, performing significantly better than all other agents. Microhardness hierarchy: Curodont™ Protect > PRG Pro-Care Gel > Apa Care Repair ≈ Tooth Mousse > ReminPro > Control. For ΔE, a significant time effect was observed (p < 0.001), but no significant intergroup differences were found (p = 0.726). A significant interaction was found for ΔL (p = 0.020), with Curodont™ Protect showing final lightness statistically indistinguishable from baseline. CONCLUSION: The choice of remineralizing agent influences enamel recovery after bleaching, particularly regarding mechanical properties. While all agents provided comparable ΔE stabilization, SAP P11-4 was uniquely effective, enabling near-complete microhardness recovery and distinct return of lightness to baseline. S-PRG and nano-hydroxyapatite also demonstrated strong efficacy. CLINICAL RELEVANCE: Within the limitations of this in vitro study, biomimetic agents such as SAP P11-4 may offer advantages for structural recovery and shade perception following in-office bleaching. Further clinical studies are warranted to confirm these findings.