Study Of Effect On Preventing And Curing Early Carles Lesions On Enamel Subsurface Of CPP-ACP In Vitro

Dental caries is one of the most serious disease which is harm to oral health. Using fluorides as anticariogenic agent has been recognized, but its toxic and side effect can not be ignored. In recent years, it has been reported that dairy products as milk, powder and cheese could exhibit anticaries activity. The components which were largely responsible for this anticaries activity have been identified as casein phosphopeptides(CPP) and amorphous calcium phosphate(ACP). This paper focuses on the effect of CPP-ACP and CPP-ACP combining with fluorides of low concentration on preventing and curing dental caries.Objective：The objective of this subject is to verify the effect and role of CPP-ACP on inhibiting demineralization and promoting enamel remineralization in vitro, and to investigate whether CPP-ACP combining with fluorides of low concentration has the synergistic effect on caries prevention and contral.Methods:Experiment1:the study on effect of CPP-ACP on inhibiting enamel demineralization in vitro.One hundred and four bovine enamel pieces were randomly divided into8groups(n=13), and immersed in saliva for24hours to obtain acquired pellicle. Each group was given different treatment (Group A:0.05%NaF; Group B:0.1%CPP-ACP; Group C:0.5%CPP-ACP; Group D:1%CPP-ACP; Group E:0.05%NaF+0.1%CPP-ACP; Group F:0.05%NaF+0.5%CPP-ACP; Group G:0.05%NaF+1%CPP-ACP; Group H:deionized water). Then all pieces were immersed in fresh streptococcus mutans solution for7days to produce artificial caries. After treatment morphology change of enamel surface was observed by scanning electron microscope(SEM). The amount of calcium in streptococcus mutans solution was tested by atomic absorption spectrometer(AAS). And microhardness of enamel surface(SMH) was detected(n=10). At last, enamel pieces(n=5) of every group were observed by confocal laser scanning microscope(CLSM) then the average luorescence in enamel pore after demineralization was analyzed.Experiment2: the study on effect of CPP-ACP on promoting remineralization of early artificial enamel caries in vitro.One hundred and four bovine enamel pieces which had been produced early artificial caries were randomly divided into8groups after demineralization. Then they were given8different treaments (Group A:0.2%NaF; Group B:0.1%CPP-ACP; Group C:0.5%CPP-ACP; Group D:1%CPP-ACP; Group E:0.2%NaF+0.1%CPP-ACP; Group F:0.2%NaF+0.5%CPP-ACP; Group G:0.2%NaF+1%CPP-ACP; Group H:deionized water) for7days to enhance remineralization. After experiment, the effects of different treatment were tested by surface microhardness(SMH), scanning electron microscope(SEM) and confocal laser scanning microscope(CLSM).Results:Experiment1:1.The results of SEM showed lots of sizes porous defects on the enamel surface of group H, while the configuration of enamel of group G was similar to the sound enamel. And varing degrees fissures and pits had been observed on the enamel surfaces of the rest groups.2.The amount of calcium of group H dissoluting in streptococcus mutans solution detected by AAS was significantly higher than the other groups (P<0.05). Except group A and C, group D and F, the difference of calcium dissolution of the rest groups was significant (P<0.05).3. Among all the groups, the SMH of group H was the lowest after experiment, and the difference was significant (P<0.05). There was no significant difference among group A、C and E, the same as group D and F(P>0.05). But change of microhardness in other groups had significant difference(P<0.05).4. Enamel pieces disseminated with Rhodmine B were observed by CLSM. There ware different widthes of fluorescentstrip from enamel surface to enamel-dentinal junction. Average fluorescence among different groups had significant difference(P<0.05), except group C and E.Experiment2:1. The pictures of SEM showed all solution except deionized water deposited mineral on the surface of decalcified enamel after remineralization. The porous defects were filled with mineral which made osteoporosis surface become dense.2.Comparing with the group of deionized water, the SMH of decalcified enamel of the other7groups were increased, and the difference was significant(P<0.05). Except group A、C and E, there was a significant difference among the rest groups in multiple comparison(P<0.05).3. Enamel pieces disseminated with Rhodmine B were observed by CLSM after remineralization. There ware different widthes of fluorescentstrip from enamel surface to enamel-dentinal junction. And average fluorescence among different groups had significant difference(P<0.05).Conclusion:CPP-ACP could reduce enamel demineralization and promote remineralization in vitro, meanwhile this anticaries ability was correlated with the CPP-ACP concentration. And CPP-ACP combining with fluorides of low concentration had the synergistic effect on caries prevention and contral.