Weekly variation in the acidogenic response of plaque

The fall in plaque pH after sucrose rinsing was monitored once a week for 9 (8) weeks in succession, to measure the weekly variation in the magnitude of pH drop in the same subject. The plaque pH was measured with a touch electrode placed interdentally between the first and second premolar. The subject rinsed his mouth with 10% (w/v) sucrose solution, and the plaque pH was thereafter monitored for 40 min. The minimum plaque pH (pHmin), the change between starting and minimum pH (delta pH), and the resting pH value were determined. The pH values of the maxilla and mandible differed. No difference was seen between the right and left sides. As a rule, intraindividual variation was lower in terms of pHmin values than in terms of delta pH values. It was concluded that pH assessment with the touch electrode appeared to show a small weekly variation intraindividually and to be sensitive enough to test the acidogenic potential of foods, but only in the maxilla.