Protective Effect of Hemoglobin Treatment with Sodium Trimetaphosphate on Enamel Erosion: in vitro study

This study aimed to evaluate the effect of hemoglobin (Hb) in combination with different concentrations of sodium trimetaphosphate (STMP) on initial enamel erosion in vitro. Ninety bovine enamel samples (4X4mm) were prepared and divided into six groups (n/group=15), according to the treatments: 1) Deionized water (negative control); 2) Commercial solution Elmex Erosion Protection® ; 3) 1.0 mg/mL Hb; 4) 1.0 mg/mL Hb+0.5% STMP; 5) 1.0 mg/mL Hb+1.0% STMP; 6) 1.0 mg/mL Hb+3.0% STMP. The samples were treated with the respective solutions (250µL, 2h, 37ºC, constant agitation), and the acquired enamel pellicle was formed for 2h using pooled stimulated human saliva. Subsequently, the samples underwent an erosive challenge with 0.01 M HCl (pH 2.3, for 10 seconds) to simulate intrinsic erosion. These procedures were performed once/day for 3 consecutive days. Demineralization was assessed by percentage surface hardness change (%SHC) and the relative surface reflection intensity (%SRI) by the Reflectometer Optipen. Data were analyzed by ANOVA and Tukey's tests (p < 0.05). The negative control exhibited significantly less protection for both variables compared to the other groups. Regarding %SHC, the most effective treatments were 1.0 mg/mL Hb + 0.5% STMP and 1.0 mg/mL Hb + 1.0% STMP, which surpassed all other groups, including the positive control. The best protection for %SRI was observed with 1.0 mg/mL Hb. These results suggest that combining Hb with an inorganic component may support the development of strategies to prevent intrinsic enamel erosion.