Bleaching efficacy and enamel effects of tricalcium phosphate dentifrices containing charcoal or hydrogen peroxide

This study aimed to evaluate the bleaching efficacy and effects of dentifrices containing tricalcium phosphate (TCP) with activated charcoal (COAL) or hydrogen peroxide (HP) on dental enamel, compared with monofluorophosphate (MFP). Bovine enamel-dentin discs (n=10/groups) were stained and divided into TCP/HP, TCP/COAL, MFP/HP, MFP/COAL, and C (control - remineralizing solution) groups. Simulated toothbrushing (5.000 cycles) was performed, representing 6 months of clinical condition. The whiteness index (ΔWID), color changes (ΔE00, ΔL, Δa, and Δb), and surface microhardness and roughness (SMH, Ra) were evaluated after staining and treatments. Morphology and mineral content were analyzed under scanning electron microscopy and energy-dispersive X-ray spectroscopy. Data were analyzed using ANOVA/Tukey or Bonferroni tests (α=5%). MFP/COAL demonstrated significantly higher Δa and Δb than C. A statistically significant difference was observed in the TCP groups only for Δa. MFP-containing groups exhibited significantly higher ΔE00 than C. All groups showed negative ΔWID. MFP/COAL promoted greater darkening than TCP-containing and C groups (p<0.05). No statistical difference was detected among groups for ΔL, SMH, Ra, and %SHL (microhardness loss) (p>0.05). No morphological alterations were observed. TCP/HP showed lower mean Ca/P values. Therefore, dentifrices containing TCP associated with HP or COAL showed no bleaching efficacy and no harmful impact on enamel surface properties.