The effects of sodium hexametaphosphate combined with other remineralizing agents on the staining and microhardness of early enamel caries: An in vitro modified pH-cycling model

BACKGROUND: This study was conducted to determine the effects of sodium hexametaphosphate (SHMP) combined with other remineralizing agents on the staining and microhardness of early enamel caries. MATERIALS AND METHODS: in This in vitro study The enamel buccal surfaces of 70 bovine incisors were classified into seven study groups (n = 10). Remineralizing agents were employed alone and in combination with SHMP in different groups, including: (1) 8% SHMP, (2) 2% sodium fluoride, (3) 2% sodium fluoride + SHMP, (4) Remin Pro(®), (5) Remin Pro(®)+SHMP, (6) MI Paste Plus, and (7) MI Paste Plus + SHMP. A modified pH-cycling technique was used to reconstruct the dynamics of caries. Colorimetric and microhardness analyses were conducted before demineralization (T(1)), after caries formation (T(2)), and after the remineralizing treatment (T(3)). The data were analyzed by the one-way analysis of variance and the repeated measurement analysis (P > 0.05). RESULTS: After remineralizing cycles, the experimental groups treated with either SHMP alone or in combination with other materials showed less significant changes in the three variables of color (Δa, Δb, and ΔL) and the overall color change (ΔE). The enamel caries treated with Remin Pro(®) presented the highest color change, while Remin Pro(®)+ SHMP resulted in the least changes. The mean value of microhardness after remineralization improved significantly in all groups, except in the MI Paste Plus + SHMP group that showed the lowest value. In contrast, the highest microhardness value was recorded for Remin Pro(®), being comparable to that of the sound teeth (P > 0.05). CONCLUSION: SHMP, either alone or combined with remineralizing agents, created the least staining. Remineralizing materials alone showed higher surface hardness, while sodium fluoride alone showed higher surface hardness when combined with SHMP.