Effect of the pH of Buffer Solutions on Artificial Carious Lesion Formation in Human Tooth Enamel

In this study a buffer system containing calcium and phosphate was used to produce caries-like lesions. The influence of the pH on the lesion characteristics was investigated. The degree of saturation with respect to hydroxylapatite and the concentration of the undissociated acid were kept constant. The pH was either 4.0, 4.5, 5.0 or 6.0. The lesions were examined microradiographically. The lesion characteristics studied were: the mineral content of the surface layer; the mineral content of the body of the lesion; the depths at which these mineral levels were reached, and the depth of the lesion. The most important influence of the pH was that on the rate of demineralization. A striking phenomenon was the sudden change in the rate at which the different levels of demineralization were reached. In solutions with a pH lower than or equal to 4.5, the time needed to reach a certain demineralization was considerably shorter than for solutions with a pH higher than or equal to 5.0.