pH measurements of human dental plaque after consumption of starchy foods using the microtouch and the sampling method.

The aim was to study the effect of different starch-containing food items on pH changes in dental plaque. The pH was, in 10 subjects, simultaneously measured at various occasions up to 60 min in: (1) two approximal spaces in the premolar-molar region with the microtouch method, and (2) pooled samples of dental plaque with the sampling method. Six starchy products were tested: (1) spaghetti, (2) macaroni, (3) potato, (4) rice, (5) unsweetened bread, and (6) sweetened bread. A glucose chewing tablet and a mouthrinse with 10% sucrose served as controls. Saliva was collected for HPLC analysis of maltose and maltotriose when testing the spaghetti, rice and unsweetened bread. The glucose tablet and the sucrose solution resulted in the greatest pH drops. However, all starchy products resulted in obvious pH falls, which were most pronounced for sweetened bread, followed, in order, by unsweetened bread and potato. Significantly more maltose and maltotriose were found in saliva after consumption of unsweetened bread compared to spaghetti. There seemed to be a relationship between the amount of starch hydrolysates in saliva and the area of the plaque pH curve (AUC). The microtouch method gave consistently lower pH values than the sampling method. Both methods, however, ranked the eight test products roughly in the same order with respect to minimum pH, maximum pH decrease and AUC.