Anti Erosion Efficacy by Prototype Hydroxyapatite Protein Composite containing Toothpastes

Objectives: The purpose of this study was to evaluate the enamel surface restoring potential of the hydroxyapatite protein composite Nanit®active (HPC) in a toothpaste formulation (AP) versus an identical but HPC free control (PP) of identical formula. Both pastes contained 1450ppm fluoride as NaF. Commercially available pastes served as further controls: Colgate Cavity Protection (CC) and Crest with NaF (CP). The HPC is nano sized hydroxyapatite particles bound to a protein component to form a composite similar to natural calcified tissue. Methods: Human enamel specimens were mounted in cold cure acrylic with an optical flat enamel surface produced by polishing. For mineralization studies, the reference surface for restoration assessment of subsequent treatments was a 10sec. exposure to 5% citric acid. This surface was treated with 1:3 slurries of the pastes for 5min. at room temperature and then equilibrated at 37°C in gently agitated simulated saliva for two hours. After 10 brushing strokes at 150 g load and rinsing the treated surface was scanned with a Mahr Federal Surfanalyzer® 5000 with a mechanical stylus and custom software to characterize and to quantitate surface restoration. Results: Surface restoration is visible and strongest for AP (64±10%). The controls yielded 32±8% for PP, 19±10% for CP and 17±5% for CC. The result for AP was significantly different from the controls. Conclusions: Etched enamel surface restoration was easily measurable after one 5min. paste treatment. The effect proved to be partly depending on the persistence of the pastes on the enamel surface and their fluoride system. The addition of HPC, however, led to an enhanced surface restoration by 32.2% compared to a HPC free paste of identical formula. The result shows the ability of HPC to restore chemically eroded enamel surfaces.