In Vitro Anti-caries Efficacy of a Whitening Toothpaste

Objectives: To assess in vitro the anti-caries efficacy of a new whitening toothpaste (1450ppm NaF) containing silica abrasive, in comparison with a positive control (Signal Karies Schutz, 1450ppm NaF) and a non-fluoridated negative control by measuring reduction of demineralisation (demin), promotion of remineralisation (remin), and fluoride up-take into demineralised enamel (F-uptake). Methods: Demin and Remin assays were carried out by pH cycling methodologies (based on Caries Res. 25:251-255, 1991; Arch. Oral Biol. 40: 879-881,1995) intended to simulate the variations in pH that occur in the mouth. For Demin, sound bovine enamel blocks were randomly allocated to the 3 groups (n=8/group). After cycling, the buffer solutions were analysed for total calcium with data expressed as Calcium Demineralisation Rate (CDR). For Remin (n=7/group), analysis was by radiography with remineralisation expressed as the difference in Integrated Mineral Loss (DIML) before/after treatment. The F-uptake assay (Caries Res. 32: 417-421, 1998) measured fluoride uptake from a toothpaste slurry (n=8/group) with data expressed as micrograms of Fluoride per enamel area exposed. Data were analysed by ANOVA with the significance level set at p=0.05. Results: The results, expressed as mean values (st.dev), for the whitening toothpaste, the positive and negative controls respectively were: demin study, CDR = 0.187 (0.025), 0.191 (0.022) and 0.513 (0.042) µg Ca.mm^-2.h^-1; remin study, DIML = 54.77 (15.86), 58.66 (12.63) and 22.74 (14.83); F-uptake = 32.44 (3.14), 30.33 (6.59) and 0.61 (0.13) µg F.cm^-2. Compared with the negative control, both the positive control and the whitening toothpaste significantly reduced enamel demineralisation, increased remineralisation and Fluoride uptake into enamel (all p<0.05). For all assays, the differences between whitening toothpaste and the positive control were not statistically significant. Conclusions: In these in vitro studies, the new whitening toothpaste showed superior anti-caries efficacy to the negative control and was equivalent to a clinically proven anti-caries toothpaste.