Effect of compounds of Galla chinensis on remineralization of enamel surface in vitro

Abstract Objective The aim of the study was to investigate the effect of chemical compounds of Galla chinensis on in vitro the remineralization of enamel surface. Method Bovine enamel blocks with in vitro produced initial lesions were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4×1 min applications with one of four treatments: Group A: 1000 ppm F aq. (as NaF, positive control); Group B: deionized water (DDW, negative control); Group C: 4000 ppm crude aqueous extract of G. chinensis (GCE); Group D: 4000 ppm gallic acid. The enamel specimens were analysed by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray microdiffraction (XRD). Results The morphology of surface enamel was different in each group. The mineral composition was identified as similar to hydroxylapatite, but the crystallite sizes of enamel in different groups were significantly different. In addition, the Ca/P ratios were significantly lower in GCE group. Conclusion GCE could affect the mineral ions deposit on the surface layer and then modified the remineralization of initial dental caries. The mechanism seems to be different between GCE and gallic acid.