Effect of CPP-ACP on bacterially induced demineralization

Objectives: The aim of this in vitro study was to investigate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on demineralization of hydroxyapatite produced by cariogenic bacteria. Methods: Streptococcus sobrinus ATCC33478 was anaerobically grown on semi-circular sintered hydroxyapatite disks with 1% sucrose changing the culture everyday. Biofilms were daily exposed to sterile water (control) or 10 times dilution of Tooth Mousse (TM, 10% CPP-ACP), MI Paste Plus (MIP, 10% CPP-ACP, 900 ppm fluoride), placebo paste (PP, no CPP and fluoride) for 5 minutes. Each group consisted of 8 specimens. After 2 weeks, demineralization of hydroxyapatite disks were assessed by radiographic image analysis using X-ray CT (TOSCANER-30000, TOSHIBA) and ImageJ. The areas (vol%•μm) between the sound and demineralized hydroxyapatite profiles (ΔZ) were calculated. Data were analyzed by one-way ANOVA followed by Tukey's multiple comparison test. Results: Mineral profile of demineralized hydroxyapatite disk in control group represented subsurface lesion like tooth enamel. Mineral loss value ΔZ (mean±S.D.) of TM (612±256) and MIP (30±38) group were significantly lower than that of PP (2066±532) and control(2266±137) group (P < 0.01).MIP achieved almost 100% inhibition of demineralization. Conclusion: CPP-ACP has inhibitory effect on demineralization caused by biofilm. This ability was enhanced by coexistence with fluoride.