AIMThe effect of Galla chinensis on de-/re-mineralization of advanced enamel lesions was investigated by using micro-CT in a prolonged in vitro experiment.

METHODOLOGYBaseline mineral contents of sound enamels were first analyzed. Then lesions were produced in an acidic buffer solution (2.2 m mol x L(-1) Ca(NO3)2, 2.2 mmol x L(-1) KH2PO4, and pH = 4.5) for 21 days, with thrice daily three-minute treatments, divided into four groups: Group A, 4 000 ppm crude aqueous extract of Galla chinensis (GCE); Group B, 4000 ppm gallic acid; Group C, 1000 ppm F aq. (as NaF, positive control); Group D, deionized water (negative control). Next, the blocks were immersed in a remineralization solution (1.5 mmol x L(-1) CaCl2, 0.9 mmol x L(-1) KH2PO4, 0.1 ppm F, and pH = 7.0) for 200 days. Mineral loss (ML) in each region of interest (ROI) and integrated mineral loss (IML) of the lesions were calculated (comparing with baseline mineral content of sound enamel) at different time points.

RESULTSAfter 21 days demineralization, fluoride treatment showed a statistically significant demineralization-inhibiting effect among the four groups, and after 200 days of remineralization, mineral content recovery was ordered (lowest to highest) as A = C < B < D.

CONCLUSIONGCE could slow down the remineralization of enamel in the surface layer and thereby facilitate ion transport into the lesion body. The mechanism of Galla chinensis in enhancing the remineralization of dental caries is different from fluoride.