Biogenic amorphous calcium phosphate: a sustainable alternative for dentin remineralization

Background Dentin demineralization weakens tooth integrity, requiring effective remineralization approaches.
Amorphous calcium phosphate (ACP) is commonly used to deliver calcium and phosphate ions for dentin repair.
However, synthetic ACP (SACP) often exhibits instability and limited antibacterial properties. In contrast, biogenic ACP
(BACP), derived from eggshell waste, presents a sustainable alternative with potential advantages.
Objective This study aimed to compare the remineralization potential of SACP and BACP by evaluating their ability
to restore microhardness, tubular occlusion, and crystal deposit formation. Antibacterial efficacy against S. mutans and
L. acidophilus was also assessed.
Methods BACP was synthesized from eggshell waste using thermal and chemical processes, while SACP was
commercially obtained. Both materials were characterized using SEM, EDX, FTIR, and XRD, with biocompatibility
verified via MTT assay. Dentin specimens (n = 36) were demineralized (pH 4.5, 72 h) and divided into BACP, SACP, and
control groups. Remineralization efficacy was assessed using pH-cycling, Vickers microhardness, SEM-EDX, and XRD.
Antibacterial activity was evaluated using the agar diffusion method and biofilm disruption was analyzed through
fluorescence microscopy against S. mutans and L. acidophilus. Statistical analysis was performed using one-way
ANOVA with Tukey’s post-hoc test.
Results SEM revealed that BACP had a more uniform, densely packed structure compared to SACP. Microhardness
testing showed BACP-treated samples had the highest post-treatment hardness (59.97 HV), followed by SACP
(53.80 HV) and control (42.30 HV). EDX showed a higher Ca/P ratio in BACP (1.64) compared to SACP (1.54), closely
resembling hydroxyapatite. BACP exhibited superior antibacterial activity in both agar diffusion and biofilm disruption
analyses.
Conclusion BACP, derived from eggshell waste, demonstrated superior remineralization and antibacterial potential,
making it a promising alternative to SACP for dentin repair.