DETERMINATION OF PLAQUE PH CHANGES WITHIN THE TROUGH OF AN IN-SITU APPLIANCE USED TO STUDY MINERAL CHANGES IN EARLY CARIOUS LESIONS

Plaque pH was measured using a glass combination pH microelectrode of plaque deposits lining the trough of an intra-oral appliance which con tained single sections of human teeth with artificial enamel lesions. Plaque exposure to a 10% sucrose solution produced significantly lower plaque pH levels than a solution of sorbitol gum extract. The subsequ ent flow of saliva over the plaque/pH electrode interface resulted in a significant and rapid increase in pH. Repeat experiments, using deio nised water instead of saliva, demonstrated no increase in pH at the p laque/electrode interface. This system may provide a convenient method of producing plaque suitable for repeated pH analysis in intimate ass ociation with artificial enamel lesions. This may permit further study of the relationship between plaque acidogenicity, salivary buffering capacity and mineral change within the incipient enamel lesion.