Characterisation of the remineralisation produced by various products in vitro

Objective: The aim of this study was to explore the pattern and extent of remineralisation produced by various commercially available products using surface microhardness and transverse microradiography. Methods: 63 extracted human molar teeth were divided into groups of seven and allocated to the following treatments: 1. artificial saliva; 2. fluoride toothpaste, 3. casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACFP); 4. Age Defying; 5. Apagard; 6. Remin Pro; 7. ClinPro; 8. Dr Collins Restore; and 9. Oravive. Products 2 and 4-9 were diluted in artificial saliva, with the fluoride concentration of the solutions standardised (100ppm). The total, soluble and free ion concentrations of each solution were measured using ion chromatography. Enamel subsurface lesions were created and half of the lesion was exposed to the various solutions for 10 days. The extent of remineralisation was determined using surface microhardness and transverse microradiography (TMR). Results: The TMR results showed that all groups (2-9) produced significantly greater remineralisation than the artificial saliva alone (11.4±1.3%) and that CPP-ACFP produced significantly more remineralisation than all other products (55.7±4.5%). The products containing Amorphous Calcium Phosphate (4) and Functionalised Tricalcium Phosphate (7) produced 21.3±3% and 20.9±1.0% remineralisation respectively, which was greater than products 8 and 9 containing Novamin (17.4±1.5%;16.7±0.4%) and products 5 and 6 containing hydroxyapatite (15.3±0.6%;16.2±0.3%). The remineralisation produced by products 5,6,8,9 were not significantly different to the fluoride toothpaste (15.4±1.3%). The amount of remineralisation achieved was significantly correlated with the apparent activity of free calcium ions in solution (p<0.05). Surface microhardness correlated poorly with transverse microradiography (p>0.05), did not provide information on the pattern of subsurface remineralisation, and was negatively affected by surface precipitation. Conclusion: All products and solutions produced some remineralisation of subsurface enamel lesions however, the extent and pattern of remineralisation varied between product types. Acknowledgements: ADRF Colin Cormie Award and Gordon Castle Scholarship