Remineralization effectiveness of the PAMAM dendrimer with different terminal groups on artificial initial enamel caries in vitro

Disruption of the demineralization–remineralization balance could trigger the development of dental caries, making it challenging for enamel to “self-heal”. Thus, extrinsic assistance is needed to restore enamel lesions and stop undermining progression. The aim of this study was to investigate enamel remineralization in a simulated oral environment via poly (amino amine) (PAMAM) dendrimers quantitatively. Bovine enamel specimens were shaken in demineralization solution (pH 4.5, 37 °C, 50 rpm/min) for 72 h to create initial enamel carious lesions. The subsurface-demineralized specimens were then divided into four groups: enamel treated with PAMAM-NH2, enamel treated with PAMAM−COOH, enamel treated with PAMAM−OH, and enamel treated with deionized water. The treated specimens underwent subsequent 12-day pH cycling. Enamel blocks were analyzed by transverse microradiography (TMR), surface microhardness testing and scanning electron microscopy (SEM) before and after demineralization and pH cycling. Groups treated with PAMAM dendrimers showed lower lesion depth and less mineral loss, attained more vertical-section surface microhardness recovery, and adsorbed more mineral deposits (p < 0.05). The enamel lesion remineralization values of PAMAM-NH2, PAMAM-COOH, and PAMAM-OH groups were 76.42 ± 3.32%, 60.07 ± 5.92% and 54.52 ± 7.81%, respectively. In conclusion, PAMAM with different terminal groups could induce enamel remineralization, among which PAMAM-NH2 showed the most prominent competence, followed by PAMAM-COOH and PAMAM-OH, in that order.