Prevention And Treatment Of Early Enamel Caries On Primary Teeth By CPP-ACP Combined With Fluoride In Vitro

Object: Casein phosphopeptides-amorphous calcium phosphate is a new kind of remineralized material,which can be used to treat initial enamel lesions,improve the acid resistance of teeth,protect teeth from dental caries or dental erosion.Since CPP-ACP can bind to fluoride ion,most of studies currently focus on the synergetic effects they create,and studies about permanent teeth account for a large proportion of all.Our project taking primary teeth as subject investigated,tries to find out the experimental evidence that CPP-ACP can enhance the remineralizing ability of fluoride,to discuss the influence of different applying modes on this synergetic effect.From then on,we take CPP-ACP anti-acid function into consideration,researching in whether the combination of CPP-ACP and fluoride can raise acid resistance or not.Besides,the influence of time on the effect of combination was also studied.The ultimate aim of this study is to provide some experimental evidence for the minimally invasive treatment of early enamel caries and to support prospective use for erosion in children clinically.Materials and methods: Twenty-five primary teeth were collected and divided into five groups(control group,CPP-ACP group,fluoride varnish group,combined group and CPP-ACFP group).Then experiments were carried out as follows.(1)Remineralization experiment:(1)Vickers hardness test: original intact enamel surface and surface of initial artificial caries,surface after experiencing 7 days and 14 days p H circle were measured.Hardness recovery rate of enamel was calculated according to the formula,then compare the difference between the groups above.(2)Scanning electron microscopy(SEM)was used to observe the surface morphology of enamel after p H circle.(2)Immediate anti-acid test:(1)Vickers hardness test: original intact enamel surface and surface after applying the remineralized material were measured.The loss rate of enamel hardness was calculated according to the formula,then compare the difference between the groups above.(2)Laser confocal fluorescence detection: staining these specimens away from light.After taking photos from enamel surface,compare the fluorescence area between five groups.(3)Acid resistance test for 7 days:(1)Vickers hardness test: original intact enamel surface and surface after applying the remineralized material were measured.The loss rate of enamel hardness was calculated according to the formula,then compare the difference between the groups above.(2)Laser confocal fluorescence detection: staining these specimens away from light.After taking photos from enamel surface,compare the fluorescence area between five groups.Results:(1)Remineralization experiment:(1)The hardness recovery rate of each treated group was higher than that of the control group(P < 0.05),but there was no significance difference between these treated groups(P > 0.05).(2)Compared to the control group,the enamel rod crystal of each treated group was repaired and granular deposits were scattered over the surface,while the control group is rough and uneven,pores can be found everywhere.(2)Immediate anti-acid test:(1)The loss rate of enamel hardness of each treated group was lower than that of the control group(P < 0.05),but there was no significance difference between these treated groups(P > 0.05).(2)The fluorescence area of each treated group was smaller than that of the control group(P < 0.05),but there was no significance difference between these treated groups(P > 0.05).(3)Acid resistance test for 7 days:(1)The loss rate of enamel hardness of each treated group was lower than that of the control group(P < 0.05).The loss rate of group CPP-ACP and group fluoride varnish were higher than the group combined and group CPP-ACFP(P < 0.05).The differences of group CPP-ACP and group fluoride varnish were not statistically significant(P > 0.05).The same happens to group combined and group CPP-ACFP(P > 0.05).(2)The results of fluorescence area was consistent with that of loss rate of enamel hardness above.Conclusion:(1)Remineralization experiment:(1)Each treated group has a remineralizing effect on early enamel caries of primary teeth.(2)When CPP-ACP is combined with fluoride,and the effect of combination is not stronger than that of CPP-ACP or fluoride used alone.(3)When used together,there is no significant difference between the low concentration and continuous applying mode of fluoride and the applying mode of single use of high concentration of fluoride.(2)Immediate anti-acid test: Preventive coated CPP-ACP benefits the acid resistance of primary enamel.(3)Acid resistance test for 7 days:(1)After applying 7 days,the combination of CPP-ACP and fluoride can improve the acid resistance to enamel of primary teeth.(2)When used together,there was no significant difference in acid resistance of primary teeth between low concentration,continuous fluoride applying mode and that of high concentration and single use of fluoride.