Comparing the Demineralisation Rates of Deciduous and Permanent Enamel.

Objectives: GA dental extractions for children in the UK are increasing. The causes are many-fold. Although there are many studies on the physical chemistry underlying the aetiology of demineralisation in human permanent enamel (PE), data relating specifically to deciduous enamel (DE) are relatively scarce. The overall aim is to understand the differentiating demineralisation characrteristics of PE and DE. The objectives of this study were to use scanning microradiography (SMR) to; establish DE baseline demineralisation rates; measure the effect of increasing the calcium and phosphate ion concentration in the demineralising solution on DE rates; and to establish whether a statistically significant difference exists between the demineralisation rates of DE and PE.
Methods: Pairs of PE and DE 2mm slabs with natural surfaces exposed were mounted into 3 SMR cells. 18 points on DE and 13 points on PE slabs were analysed using SMR. Samples were initially immersed in deionised water for 48h; then demineralising solution (acetic acid pH 4.0) was circulated for 48h. Real-time SMR was used to measure the rate of mineral loss at each point. Then, 0.5mmol l^-1 calcium ions and 0.3mmol l^-1 phosphate ions were added to the demineralising solutions, and mineral loss rates re-measured. Thereinafter; 1mmol l^-1 calcium ions and 0.6mmol l^-1 phosphate ions were sequentially added to the demineralising solution every 48h and the rates of mineral loss measured continuously using SMR.
Results: The mean baseline demineralisation rates were not significantly different (p<0.05%) at 3.96 x 10^-4 gcm^-2 hr^-1 (DE) and 4.54 x 10^-4 g cm^-2 hr^-1 (PE). The demineralisation rate in DE and PE decreased as the calcium ion concentration was increased, and both followed similar trends.
Conclusions: These results show that DE demineralises slower than PE but this was not significant (p<0.05%). Increasing the calcium and phosphate ion concentrations in the demineralising solution reduces the PE and DE demineralisation rates, and both follow similar trends.