Methods: Test HAp powders were mixed for 24h with either deionised water (control), bovine serum albumin (BSA)-Sigma Aldrich A-9647 (2g/l), or fluoride (1ppm, positive control), filtered, and air-dried for 48h at room temperature. One well of an environmental SMR cell was filled with 0.1g of HAp powder (control), the other with same amount of test powder. As an additional control in two cells dry HAp powder was run against “wet” powder. The powder was protected from dispersal with a 1mm thick disk of protective porous polyethylene or a covering layer of agarose gel (2 series of cells). 0.1M acetic acid buffered to pH 4.5 was used as a demineralising solution which circulated through cells at approximately 0.4 ml/min. SMR was used to observe changes in mineral mass. Two scans were made with 11 points at each line; scanning time was 30 s per point, total period of observation was 21 days. Demineralisatiom rates were calculated using linear least squares fitting.
Results: The average rate of demineralisation for control HAp was 0.40x 10-4g/cm2, for BSA coated HAp powder was 0.39x 10-4 g/cm2, for HAp powder mixed with fluoride was 0.12x10-4g/cm2. There was no significant difference in demineralisation rate between control and samples coated with BSA.
Conclusion: Coating HAp with BSA neither prevented nor reduced the rate of demineralisation.
Acknowlegements: MRC Programme Grant G9824467, The Wellcome Trust Grant 062850, and QMUL Studentship