COMPARISON OF 3 DIFFERENT METHODS FOR MEASUREMENT OF PLAQUE-PH IN HUMANS AFTER CONSUMPTION OF SOFT BREAD AND POTATO-CHIPS

Three different techniques for measurement of plaque-pH - the sampling , the microtouch, and the telemetric methods - were compared after sub jects had consumed different starch products. Ten volunteers, equipped with partial lower prostheses, incorporating a miniature glass pH ele ctrode, refrained from toothbrushing for 3 days. Four products were te sted: (1) soft bread, (2) potato chi ps, (3) 5% starch, and (4) 5% suc rose. The pH of plaque was measured for 45 min by means of all three o f the methods. The results showed that the mean pH at 10 min was 1.5 u nits lower with the telemetric than with the sampling method and 1.0 u nit lower with the telemetric than with the microtouch method. Relativ ely small differences were found among the effects of the four test pr oducts for all three methods, with the clearest distinctions among the pH curves being with the microtouch and telemetric methods. The main conclusions from the present investigation are: (1) that there were la rge differences in pH levels measured with the sampling, the microtouc h, and the telemetric methods, even though they ranked the test produc ts in about the same order, and (2) that the two starchy foods, bread and potato chips, were both easily fermented by dental plaque.