Objectives: The soft drinks affect directly on the teeth decalcification and cariogenecity. The purpose of this study was to measure intra-plaque pH by telemetry during the intake of several soft drinks in Korea.
Methods: Telemetry is the method, which measures continuous intra-plaque pH change by using appliance including micro-electrode for four subjects. By using this method, intra-plaque pH change and recovery speed was measured during intake of carbonated drinks(Coca-Cola??), sports drinks(Gatorade??), orange juice, yoghurt and sweetened can coffee. For measuring change of pH, Area Under the Curves(AUC) were calculated for the time periods, 2-30 minutes.
Results: The plaque pH of Coca-cola was rapidly decreased to pH 4.69 directly after injection and after 20 seconds recovered to critical pH 5.5. In orange juice, plaque pH was also rapidly decreased to pH 5.43 directly after injection and after 10 seconds recovered to pH 5.5. Plaque pH of yoghurt was decreased to pH 5.10 directly after injection; however, it did not recover to pH 6.2 until 30 minutes. Plaque pH of sports drink(Gatorade??) was also rapidly decreased to pH 5.17 directly after injection and recovered critical pH 5.5 after 40 seconds. In sweetened can coffee, plaque pH was raised to pH 7.41 directly after injection and then decreased slowly to 6.98. According to the measurement of plaque pH changes by AUC, yoghurt, gatorade, cola, orange juice and coffee, in that order, were the highest values of AUC for 0-2 minutes and 0-30 minutes. There were significant differences in AUC6.2 between yoghurt and orange juice for 0-2 minutes and in between yoghurt and cola, orange juice during 0-30 minutes.
Conclusions: These results show that yoghurt has the high potential for tooth decalcification and cariogenecity. Therefore, there is necessary special caution to children and their parents against frequent intake of soft drinks or drinking before sleeping.