Remineralization of Acid-Etched In Vitro Enamel Caries With CPP-ACP

Objectives: This in vitro study evaluated acid-etching (AE) and casein phosphopeptide-amorphous calcium phosphate pastes without fluoride (CPP-ACP) and with fluoride (CPP-ACP-Fl) on in vitro enamel caries remineralization.
Methods: 10 human teeth with sound enamel surfaces were sectioned into 3 portions. Each portion underwent in vitro caries formation (10 days - alternating 8h demineralization followed by 16h remineralization). Longitudinal sections were prepared from each tooth portion and lesion depths were determined (polarized light microscopy). In vitro enamel lesions underwent AE (37% phosphoric acid 15s, followed by air-water rinsing 60s). Each tooth portion from a single tooth was assigned to treatment group: 1) Synthetic Saliva (SS) Only; 2) CPP-ACP (MI Paste); and 3) CPP-ACP-Fl (MI Plus Paste). SS Only Group was exposed to SS for 14d period (twice daily replenishment). CPP-ACP and CPP-ACP-FL Groups were treated twice daily (14d for 120s, followed by air-water rinsing 60s), and then exposed twice daily to fresh SS between treatments. Longitudinal sections (3 sections/tooth portion) were obtained and lesion depths were determined (polarized light microscopy, ANOVA, DMR).
Results: Mean lesion depths were: 1) Control Group: 392±24um; 2) AE followed by SS Alone Group: 311±27um; 3) AE followed by CPP-ACP Group: 257+33um; 4) AE Followed by CPP-ACP-Fl Group: 193+21um. Mean lesion depth reductions compared with Control Group were: 21% for SS Only (P<.05, ANOVA, DMR), 34% for AE followed by CPP-ACP (P<.05, ANOVA, DMR) and 51% for AE followed by CPP-ACP-Fl (P<.05, ANOVA, DMR). Both CPP-ACP (17%) and CPP-ACP-Fl (38%) reduced lesion depth significantly compared with SS Only (P<.05, ANOVA, DMR). CPP-ACP-Fl (25%) significantly reduced lesion depth compared with CPP-ACP (P<.05, ANOVA, DMR).
Conclusions: Remineralization of acid-etched in vitro enamel caries was enhanced with both casein phosphopeptide-amorphous calcium phosphate agents compared with synthetic saliva rinsing alone (P<.05). The greatest degree of remineralization of acid-etched in vitro enamel lesions occurred with the casein phosphopeptide-amorphous calcium phosphate paste containing fluoride. Acid-etching is known to provide a more reactive enamel surface and may enhance remineralization of enamel caries using calcium-phosphate-fluoride agents.