Galla chinensis Compounds Remineralize Enamel Caries Lesions in a Rat Model.

OBJECTIVES: To investigate the effect of Galla chinensis chemical compounds on enamel caries remineralization in rats. METHODS: A total of 40 rats were inoculated with Streptococcus sobrinus 6715 and fed a cariogenic diet (Keyes 2000). The rats were randomly divided into 4 groups and treated topically twice a day with each of the following extracts (or control) for 5 weeks: distilled and deionized water (DDW, negative control); 1,000 ppm NaF (positive control); 4,000 ppm G. chinensis crude aqueous extract (GCE), or 4,000 ppm gallic acid (GA). After the experimental period, Keyes' caries diagnosis and scoring technique was applied as a preliminary evaluation on the molar teeth. For more accurate remineralization data, the residual enamel volume of the first molar and the mineral density (MD) of the enamel were further analyzed by micro-CT. RESULTS: The severity of molar enamel caries decreased in the following order of treatment groups: DDW > GA > GCE > NaF (p < 0.05). In addition, the residual first molar enamel volume and MD values increased in the order of DDW, GA, GCE and NaF treatment groups (p < 0.05). In most molars, remineralization layers were observed on the surface of lesions. CONCLUSION: G. chinensis compounds remineralize enamel caries lesions in a rat model.

[The effect of coaggregation of A.viscosus and P.gingivalis on the adherence of A.viscosus to hydroxyapatite].

PURPOSE: To examine the effect of coaggregation of A.viscosus and P.gingivalis on the adherence of A.viscosus to saliva-coated hydroxyapatite(S-HA). METHODS: The suspensions of A.viscosus and P.gingivalis were rotated and dropped on cover slips to visualize the coaggregation under scanning electron microscope(SEM). Different concentrations of P.gingivalis were mixed with A.viscosus radiolabeled with 10 uCi of [methyl-(3)H] thymedine per milliliter, then rotated for periods up to 1.5 hours at room temperature and the numbers of absorbed A.viscosus cells were determined by liquid scintillation. A.viscosus alone was used as the control, and its adhesion percent was set for 100%. One-way ANOVA with SPSS10.07 software package was used to analyze the effect of P.gingivalis on adherence of A.viscosus. RESULTS: Several cells of P.gingivalis could aggregate on the surface of A.viscosus. The adherence of A.viscosus to S-HA was promoted slightly when the concentration of P.gingivalis was rather small, then further increase in concentration of P.gingivalis resulted in a steady decline in the number of adherent A.viscosus, and the difference was significant (P<0.05). CONCLUSION: These results show that the adherence of A.viscosus to S-HA could be influenced by coaggregation of P.gingivalis and A.viscosus.

[Effect of chemical compounds of Galla chinensis on enamel surface rehardening in vitro].

OBJECTIVE: To evaluate the effect of chemical compounds extracted from Galla chinensis on enamel surface rehardening in vitro. METHODS: Sixty bovine enamel blocks with early carious lesions were randomly divided into six groups: group1 treated NaF (positive control); group2 with GCE; group3 with GCE-B; group4 with GCE-B1; group5 with GCE-B2 and group6 with deionized water (negative control). The lesions were subjected to a pH-cycling regime for 12 days. Surface enamel microhardness was measured on the enamel blocks before and after demineralization. After pH-cycling, and the percentage of surface microhardness recovery (SMHR) was calculated. RESULTS: Obvious increase of the surface hardness of the enamel was observed in all the treatments except GCE-B2 and deionized water (P < 0.05). CONCLUSIONS: The present study demonstrates the potential of the three GCEs (GCE, GCE-B and GCE-B1) to effect net rehardening of artificial carious lesions under dynamic pH-cyclic conditions.