Effect of dentifrices pH on enamel remineralization in vitro

AIM Demineralization and remineralization equilibrium of enamel depends on salivary Ca and P concentration, bioavailability of fluoride and pH. The aim of this study was to investigate the influence of pH of dentifrices with different fluoride formula on enamel remineralization using surface microhardness test. METHODS Enamel blocks were ground flat with water-cooled carborundum discs (320, 600 and 1200 grit) and divided into seven groups. The specimens were subjected to a daily cycling regime comprising two one-minute brushing treatments ; one before and one after demineralization period of 6 hours and 18 hours, and remineralization in artificial saliva. Enamel blocks were treated with fluoride dentifrices: Sensodyne Rapid (pH 6.7), Colgate Total (pH 7.3), Parodontax fluoride (pH 7.9), Sensodyne fluoride (pH 5.4), Pronamel Sensodyne (pH 7.1), Elmex-GABA International (pH 4.8), and fluoride free Detartrine Paste (pH 8.6). The surface microhardness (SMH) was determined at baseline and after 12 days using HMV-2000 (50 g, 490.3 mN, 10 s) (Shimadzu, Japan). RESULTS All specimen groups treated with fluorides showed increase in SMH compared to control group. Dentifrices with lower pH (Sensodyne F, Sensodyne Rapid, Pronamel) were statistically superior to other fluoride dentifrices and a fluoride-free control after 12 days pH-cycling regime (p 0.05). CONCLUSIONS Results obtained in the present study show that slightly acidified fluoridated dentifrices may have a certain effect on enamel remineralization.