Change in pH of plaqne and 10% carbamide peroxide solution during uightguard vital bleaching treatment

The purpose ofthis study was to evahtate in vivo dianges in the pH of plaque and of a 10% carbamide peroxide solution occurring within the bleaching guard during a 2-hour nightgiuird vital bleaching procedure. Baseline pH values for plaque and the carbamide peroxide solution were established. A small hole was placed in the anterior interproximal region ofthe guard to allow placement ofthe pH electrode. The pH ofthe carbatnide peroxide solution was measured at 5-minute intervals. Afier 2 hours, the guard was removed andpH of the plaque was remeasured. The procedure was repeated three times on each offour subjects. The mean baseline pH reading for plaque was 6.31 and mean fuml pH readingwas 6.86, The difference was statistically significant. At initial placement of the carbamide peroxide-fdled guard, the mean intraguard pH was 4.50 (range of 2.80 to7.80j. The mean peak intraguard pH of 8.06 (range of 7.30 to 8.43), whieh was significantly different from baseline, was obtained within 31 minutes. The p 11 of plaque, saliva, and a 10% carbamide peroxide bleaching solution within the guard increased significantly during bleaching and remained significantly elevated for the duration ofthe study (2 hours).