Comparative Evaluation of the Effect of CPP-Acp, Bioactive Glass, and Nano- Hydroxyapatite on Dentin Surface Microhardness and Surface Roughness of Non-Carious Lesions: An in Vitro Study

Aim: To evaluate and compare the effect of three different remineralizing agents on dentin microhardness and surface roughness of non-carious lesions. Materials and Methods: Forty human mandibular molar teeth extracted for periodontal or orthodontic reasons were collected, cleaned, disinfected, decoronated, and stored in distilled water. Enamel from buccal and lingual surfaces was removed to expose dentin (0.5 mm depth), and specimens were polished for standardization. Each tooth was sectioned, mounted in acrylic resin blocks, and prepared for microhardness and surface roughness analysis. Baseline dentin microhardness was measured using a Shimadzu Vickers microhardness tester, and baseline surface roughness was assessed using a profilometer. Specimens were randomly divided into four groups (n=10): CPP-ACP [GC Tooth Mousse plus], bioactive glass [Elsenz], nano-hydroxyapatite [Perfora], and artificial saliva (control). Demineralization was induced using 37% phosphoric acid for 15 seconds. Post-demineralization measurements were recorded, followed by application of the respective remineralizing agents for 5 minutes daily for 15 days. Control specimens were stored in artificial saliva at 37°C. Final dentin microhardness and surface roughness were then evaluated. Results: All groups showed reduced dentin microhardness and increased surface roughness after demineralization. Following remineralization, all experimental groups showed significant improvement compared with the control group (p < 0.001). Bioactive glass demonstrated the highest microhardness and lowest surface roughness, followed by nano-hydroxyapatite and CPP-ACP. Conclusion: All three remineralizing agents improved dentin microhardness and reduced surface roughness, with bioactive glass showing the highest remineralization potential.