Abrasivity of Desensitizing Dentifrice Containing Sodium Metasilicate

This in vitro study compared the abrasivity of commercial desensitizing dentiftices with a sodium metasilicate (Na2SiO3) dentifrice using a Surface Profile Method. Dentin specimens were made from the root of extracted human molars. The cervical part of the teeth was sectioned with a diamond wheel disk. The teeth were embedded into an epoxy resin mold and the surface Was gradually polished by silicone carbide paper. After grinding, the degree of surface toughness was tested within the range of 2 mm with tapping. The British Standard Institution reference dentifrice (BSI: CaCO3 40%) and experimental dentiffices (group 1: Na2SiO3 25%, CaCO3 10% and SiO2 10%, group 2: CaCO3 10% and SiO2 10%, group 3: CaCO3 10% and SrCl2 10%, group 4: Colloidal Silica 2-3% and Hydroxyapatite 10-20%) were evaluated. The dentifrice slurries were prepared by mixing 24 grams of the dentifrice in 12 ml distilled water. Each tooth specimen was brushed with the dentifrice slurries 1 000 times. The relative abrasivity of each dentifrice was evaluated from the ratio of the BSI standard dentifrice to each experiment. The results were analyzed by one-way ANOVA and Tukey's multiple comparisons using Window SPSS (Statistical analysis system) 12.0. Groups 1 (7 1), 2 (74.2), 3 (38) and 4 (7.8) showed a lower abrasivity than the BSI dentifrice (100) (p < 0.05). The relative abrasivity of groups 3 (38) and 4 (7.8) was the lowest compared with the BSI dentifrice (100). However, group 1 (7 1) containing Na2SiO3 showed a similar abrasivity to group 2 (74.2), which did not contain Na2SiO3 (p > 0.05). Therefore, Na2SiO3 had no influence on the abrasivity of the dentifrice. In conclusion, the dentifrice containing Na2SiO3 had a lower abrasivity than the BSI reference dentifrice, but showed a significantly higher abrasivity than the existing commercial desensitizing dentiftices. Overall, the relatively high abrasivity of Na2SiO3 dentifrice is believed to be the result of other components in the abrasive system.