Assessment of Desensitizing Ingredients in a Tubule Occluding Toothpaste

Insoluble ingredients in conventional toothpastes sometimes interfere with the standard method for assessing tubule occlusion (Pashley et al). Thus, toothpastes with minimal desensitizing efficacy often produce large reductions in dentin tubule fluid flow. Objective: The purpose of this study was to assess the calcium and phosphate components in a new desensitizing fluoride-toothpaste for their ability to occlude dentinal tubules in the absence of other insoluble toothpaste ingredients. Method: Fluid flow reductions through acid-etched coronal dentin disks, due to treatment with an aqueous mixture of the desensitizing ingredients (DI) in a British sensitivity toothpaste marketed as Enamel Care SensitiveŽ (ECS) or with a 1.25% potassium nitrate solution (KN), were compared. Additionally, optical interference profilometry (OIP), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analyses were obtained on untreated and treated dentin surfaces, and dentin treated with slurries of ECS, insolubles-free-desensitizing toothpaste (ECS without SiO2/TiO2) and placebo toothpaste (P). Results: After forty 5-minute treatments, fluid flow reduction due to DI averaged 52.5% compared with 10.6% for KN (p<0.02). OIP and SEM scans of the dentin show extensive mineral deposition and occlusion of many of the tubules by DI, ECS and ECS without SiO2/TiO2, but not by KN or P. EDX analyses of the mineral deposits indicate a 1.7:1 calcium-to-phosphate ratio, consistent with ACP formation, and the presence of SiO2/TiO2 on the ECS-treated dentin. Conclusion: The calcium and phosphate ingredients present in the Sensitive toothpaste are effective in occluding dentinal tubules and reducing dentinal tubule fluid flow.