Simulated oral interactions of acid eroded enamel with toothpastes

Objective:To assess the sequential interaction of toothpaste, salivary components and acidic challenge on an acid eroded enamel surface. Methods: Referenced etched enamel specimens were prepared using permanent bovine enamel polished to an optical flat and scanned with Mahr Federal Surfanlyzer 5000. The specimens were then taped to protect initial baseline, etched for 10 sec. with 5% citric acid, tape removed and enamel surface scanned again. Enamel specimens were agitated with 1:3 toothpaste slurries containing either ion balanced or artificial saliva with 2% mucin for 5 min., then equilibrated at 37ºC for one hr. in agitated water bath at 37°C, challenged with ISO 1% citric acid at pH 3.9 for 2 min. and equilibrated at 37ºC for 1 hr. The treatments were done in two 4X4 Latin square studies using ion balanced saliva or complete artificial saliva with mucin for the toothpaste treatment step with three commercial products: A, an 1100ppm NaF silica; B and C, two toothpastes containing triclosan/copolymer formulated with 1100ppm NaF differing in their abrasive system. Results: Acid etched enamel is a friable surface with increased porosity that reacts competitively with salivary and toothpaste components. The artificial saliva with compete array of ions reacted with etched enamel to provide a thin surface layer, whereas the artificial saliva with mucin added laid down a thicker layer with control and toothpaste treatments. Toothpastes B and C restorative treatment layers were more resistant to acid challenge, maintaining restored surface and the initial post etched baseline enamel. These restored surfaces were also more resistant to sonication demonstrating further surface stability. Conclusion: The simulated oral milieu model provided insight into the individual and combined responses of eroded enamel surfaces to the sequential, competitive, interactions occurring with toothpaste use in the mouth.

Study was supported in part by the Colgate-Palmolive Co.