Enamel remineralization and color stability induced by biogenic calcium oxide from eggshell and snail shell under pH cycling: An in vitro study

Abstract

Biogenic calcium oxide (CaO) derived from eggshell and snail shell biowaste was synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX), then evaluated for its effects on enamel surface mineral deposition and color changes under pH-cycling conditions. Thirty-six enamel specimens were assigned to six groups: sound control, demineralized control, pH-cycling control, eggshell CaO, snail shell CaO, and 0.05% sodium fluoride. Descriptive SEM observations showed surface deposits and reduced porosity in the treated groups, while EDX revealed numerical but non-significant differences in calcium, phosphorus, and Ca/P ratio among groups. Color analysis showed that the untreated pH-cycling group exhibited significantly greater hue changes than the three treatment groups, with no significant differences among the treatments. These findings provide preliminary evidence that shell-derived CaO treatment is associated with enamel-surface deposition and reduced hue alteration under in vitro conditions, warranting further investigation using quantitative subsurface remineralization methods.