Comparative evaluation of remineralization and microhardness of demineralized primary enamel treated with casein phosphopeptide amorphous calcium phosphate and chitosan hydrogel: An in vitro study

BACKGROUND: Dental caries is a chronic microbial disease, characterized by progressive enamel demineralization. Improved understanding of its pathogenesis has shifted dentistry toward minimally invasive biomimetic strategies such as Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). Chitosan, a natural polysaccharide with antibacterial and biomimetic mineralization properties, has recently emerging as a promising alternative. Hence, this study compared the remineralization efficacy of CPP-ACP and chitosan hydrogel on artificially induced enamel lesions on primary enamel. METHODOLOGY: Thirty-six extracted human molars were sectioned into four parts: sound enamel (control), demineralized enamel, and two experimental groups - Group A (CPP-ACP) and Group B (chitosan hydrogel). Demineralization was carried out for 96 h followed by remineralization using a 21-day pH-cycling model with twice-daily application of the respective agents. Energy-dispersive X-ray spectroscopy was used for Ca/P ratio analysis in all specimens. Surface microhardness (SMH) was assessed using Vickers microhardness testing for all the samples. A separate subset of three samples from each group evaluated under the scanning electron microscopy (SEM) for surface morphological assessment. Statistical analysis was performed using the Kruskal-Wallis and pairwise Mann-Whitney U -tests ( P < 0.05). RESULTS: Group B demonstrated higher SMH (211.2 ± 32.5) and Ca/P ratio (1.74 ± 0.08) compared to Group A. Significant differences were observed among the groups. Pairwise analysis showed both CPP-ACP and chitosan hydrogel significantly improved the Ca/P ratio compared to demineralized enamel ( U = 66.5, P < 0.001), while the chitosan group demonstrated Ca/ P values comparable to sound enamel. SEM analysis revealed more uniform enamel-like crystal deposition in Group B. CONCLUSION: Chitosan hydrogel demonstrated superior remineralization compared to CPP-ACP, highlights its potential as a nonfluoridated, biomimetic, clinically translatable material for enamel remineralization.