Dentin Abrasivity of Seven Grades of Sodium Bicarbonate Crystalline Powder

The British Standards Institute Radiotracer Method (BS5136) specifies a graded dilution of toothpaste slurry to mimic salivary dilution occurring during brushing. Water-soluble abrasive systems such as sodium bicarbonate are partially dissolved in the fixed paste 1:1.6 ratio of the ADA and ISO 11609 Radiotracer Method; thus the reported dentin abrasivity may be somewhat lower than it would be with the BSI Method. Objective: This study was to measure the dentin abrasivity of seven grades of sodium bicarbonate in the same toothpaste formulation in 1:1 aqueous slurry and the same sodium bicarbonate grades as crystalline powders at the same concentration in glycerin. The solubility of sodium bicarbonate in glycerin should be minimal thus the reported abrasivity should not be reduced by water solubility of bicarbonate. Method: The dentin abrasivity method used cast 3 mm thick acrylic strips brushed with the ADA Reference medium hard, flat profile toothbrush with 150gm load. Mahr Federal Surfanalyzer 5000® Profilometer was used to measure surface wear and other surface characteristics before and after brushing. The currently available Calcium Pyrophosphate Reference produced by Solutia was used as a reference for both aqueous and glycerin phases of the study. Results: The abrasivity of calcium pyrophosphate in glycerin was higher than that in the CMC, glycerin, water slurry, but the surface modifications were less. The abrasivity of sodium bicarbonate grades was comparable in simulated paste slurry and glycerin. Conclusion: Sodium bicarbonate crystalline powder in the seven grades of particulate are very soft indicating that dentin abrasivity data is appropriate and that cleaning power may result substantially from chemical cleaning. This study was supported in part by Church & Dwight Company, Inc. hefferen@ku.edu