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 (T1) , after caries formation (T2), and after the remineralizing treatment (T3). 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 (∆a , ∆b, and ∆L) and the overall color change (∆E). 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

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