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.

Animals ; Cariostatic Agents ; therapeutic use ; Cattle ; Dental Enamel ; chemistry ; drug effects ; Drugs, Chinese Herbal ; therapeutic use ; Gallic Acid ; therapeutic use ; Image Processing, Computer-Assisted ; Materials Testing ; Minerals ; analysis ; Plant Extracts ; therapeutic use ; Sodium Fluoride ; therapeutic use ; Time Factors ; Tooth Demineralization ; prevention & control ; Tooth Remineralization ; methods ; X-Ray Microtomography

To determine the chemical composition of Galla chinensis extract (GCE) by several analysis techniques and to compare the efficacy of GCE and its main component(s) in inhibition of enamel demineralization, for the development of future anticaries agents, main organic composition of GCE was qualitatively determined by liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) and quantified by high-performance liquid chromatography-diode array detector (HPLC-DAD). Inorganic ions were tested by inductively coupled plasma-atomic emission spectroscopy and F was especially measured by ion chromatography. Then, bovine enamel blocks were randomly divided into four treatment groups and were subjected to a pH-cycling regime for 12 times. Each cycle included 5-min applications with one of four treatments: 4 g⋅L(-1) GCE solution, 4 g⋅L(-1) gallic acid (GA) solution, 1 g⋅L(-1) NaF solution (positive control), deionized water (DDW, negative control), and then 60-min application in pH 5.0 acidic buffer and 5-min application in neutral buffer. Acidic buffers were retained for calcium analysis. The main organic composition of GCE were GA and its isomer, and, to a lesser extent, small molecule gallotannins. The content of GA in GCE was 71.3%±0.2% (w/w). Inorganic ions were present in various amounts, of which Ca was (136±2.82) µg⋅g(-1), and Zn was (6.8±0.1) µg⋅g(-1). No F was detected in GCE. In pH cycling, GA showed an effect similar to GCE in inhibiting enamel demineralization (P>0.05). GA was found to be the main effective, demineralization inhibiting component of GCE and could be a promising agent for the development of anticaries agents.
Animals ; Calcium ; analysis ; Cariostatic Agents ; therapeutic use ; Cattle ; Chromatography, High Pressure Liquid ; Chromatography, Liquid ; Dental Enamel ; Drugs, Chinese Herbal ; chemistry ; therapeutic use ; Gallic Acid ; analysis ; therapeutic use ; Hydrolyzable Tannins ; analysis ; Mass Spectrometry ; Polyphenols ; analysis ; Random Allocation ; Tooth Demineralization ; prevention & control