The Effect Study Of Black Tea Theaflavins On Dentin Caries

Objectives Streptococcus mutans(S.mutans)and Matrix Metalloproteinases(MMPs)are two of the cariogenic factors in caries.This study aimed to examine the potential inhibitory effect of black tea theaflavins(TFs)on S.mutans and MMP-2,-9 in the context of preventing dentin caries.Methods Three experiments were conducted.1)The minimal inhibitory concentration(MIC)and the minimal bactericidal concentration(MBC)were determined by using a broth-dilution technique.The experimental groups contained 100 μl bacterial suspension and 100 μl TFs in concentrations of 0.125,0.25,0.5,1,2,4,or 8 mg/ml.The growth control group contained 200 μl bacterial suspension,and the sterility control group contained 200 μl TFs in the aforementioned concentrations.MBC was derived from MIC.To investigate the effect of TFs on S.mutans,ApH values were elucidated by adding bacterial suspension to three different concentrations of TFs(1/2 MIC,1/4 MIC,1/8 MIC)and recording pH values before and after anaerobic incubation.Statistical analysis was conducted using an ANOVA test.The morphology of bacteria treated with TFs of the MIC and MBC was observed using scanning electron microscopy.2)Twenty-five intact human teeth were used for gelatin zymography in order to investigate MMP-2 and-9.Enamel,roots and pulp tissue were removed and coronal dentin was pulverized to powder under liquid nitrogen.After treated with 37%H3PO4 for 1 minute,the demineralized dentin powder was divided to 7 groups:group 1,EDTA treatment;group 2,only acid treatment;group 3-7,demineralized dentin powder was treated with different concentrations of TFs.The concentrations were 0.1,0.2,0.4,0.8 or 1.6mg/ml respectively.The extractions of specimens were analyzed by zymography to detect the activity of MMP-2 and-9.3)Twenty-four 25-day old Sprague Dawley(SD)rats were divided into three groups randomly.Each group contained 4 male rats and 4 female rats.In the first three days of experiment,rats were fed with normal food and water with 0.5 μg/ml Ampicillin Sodium.Then rats were infected with 108 CFU/ml bacteria suspension for five days continuously.Cries-inducing diet 2000 and water with 5%sucrose were given at the same time to form caries model.From the 9th day,rats were treated with different drugs twice a day.The experimental group was treated with MIC concentration of TFs while the positive group was treated with 250 ppm Sodium Fluoride.The negative group was given water only.After five weeks,the rats were sacrificed.The maxilla and mandible were cleaned and stained to observe caries.A method of Keyes was used to score the teeth.Results 1)The MIC was 0.5 mg/ml,and the MBC was 1.0 mg/ml.The inhibitory effects of 1/2 MIC and 1/4 MIC of TFs on bacterial acid production were statistically significant(p<0.05)compared to the control group,whereas 1/8 MIC concentration of TFs did not demonstrate a statistically significant effect(p>0.05)compared to the control group.Furthermore,S.mutans treated with TFs changed in shape from globular to rod-shaped and had disruptions to the bacterial chain structure.2)With the increasing concentration of TFs,the activities of MMP-2 and-9 were decreasing.3)TFs has significant effect on enamel caries compared to water group(p0.05)as well as NaF.Both TFs and NaF have good inhibitory effect on dentin caries,but TFs is a little bit weaker than NaF.They have almost the same significant effect on smooth caries.Conclusions TFs can inhibit streptococcus mutans and MMP-2,-9.It also have an inhibitory effect on dental caries.