The effect of different methods of drinking on the pH of dental plaque in vivo.

The effect on the pH of human dental plaque of rinsing and drinking with or without a straw was investigated in eight volunteers using the plaque sampling method. A fruit-based juice was used as the test drink with 10% sucrose and 10% sorbitol solutions serving as positive and negative controls, respectively. The maximum mean plaque pH drop (+/- SD) when a fruit juice was consumed with a straw (0.82 +/- 0.27) was significantly less (P < 0.05) as compared to when it was consumed straight from a cup without a straw (1.14 +/- 0.25) and when it was used as a rinse (1.25 +/- 0.21). Also, the minimum plaque pH reached after challenge was significantly lower (P < 0.0005) when the subjects rinsed before swallowing (5.22 +/- 0.13) as compared with drinking with a straw (5.92 +/- 0.39) or without (5.64 +/- 0.2). The area under the plaque pH curve was also found to be significantly less when a straw was used (1.81 +/- 0.71) as compared with drinking without (2.72 +/- 0.93). Drinking with a straw therefore resulted in a less pronounced pH drop and hence might reduce the demineralizing effect on the teeth of various potentially cariogenic drinks.