Quantitative Measurements of the Demineralisation Rates and Mineral Masses of Deciduous and Permanent Enamel

PhDHuman deciduous and permanent enamel samples were simultaneously exposed to 0.1 M acetic acid pH 4.0 solution with an increasing calcium and phosphate concentration. Demineralisation rates at each calcium and phosphate increment were measured by scanning microradiography (SMR) to monitor in real-time the demineralisation trend. No significant differences (p > 0.05) were observed between baseline demineralisation rates of each enamel type. Similarities in the demineralisation trend as a function of increasing calcium and phosphate concentration were also observed. SMR detected a halt in demineralisation rate at 30 mM and 32.5 mM calcium concentration for permanent and deciduous enamel equilibrium between the solution and enamel samples had been achieved. Comparisons of the SMR data with a speciation software program indicated the solubility product of deciduous and permanent enamel is 121 in pH 4.0 and 25 ⁰C conditions. X-ray Microtomography (XMT) results of the mineral concentrations of each enamel type showed no significant differences (p >0.05) and Confocal laser scanning microscopy (CLSM) image analysis of rhodamine B dye infiltration showed no significant differences between the interprismatic regions of each enamel type (p >0.05), complementing the SMR data. Permanent enamel exhibited significantly larger prism head diameters near to the surface of enamel compared to near the EDJ, whereas prism head diameters in deciduous enamel remained relatively constant throughout enamel. Thus the high caries incidence rates amongst children may be due to a lower level of protection offered by saliva and the oral environment of a child compared to an adult rather than the structure and the physical chemistry of the tissue itself.GlaxoSmithKline and Biotechnology and Biological Sciences Research Counci