pH changes by Streptococcus sobrinus on some commercial drinks

Streptococcus sobrinus에 의한 일부 시판음료의 pH 변화

Objectives: The purpose of this study was to investigate the dental caries activity of some commercial drinks. Methods : Acidity levels were recorded as pH values of original drinks and amount of 50%-sodium hydroxide(NaOH) required to neutralize by titration 50.00ml of the drink(It was called titratable acid). Acidity of the drinks with S. sobrinus was measured at an interval of one hour after incubating ($37^{\circ}C$) the test drinks and control solution which was composed 20.00ml of neutralized drinks as pH 7.0 with 0.2ml of a pooled suspension of S. sobrinus. Results : The drink with the highest pH value was the Cow's milk(pH $6.70{\pm}0.01$), and the most acidic was the Carbonated drink(pH $2.40{\pm}0.02$). The drink with the highest buffer effect was the Fruit juice($139.78{\pm}0.76$), and the lowest was the Glucose solution(control, $4.42{\pm}0.20$). The drinks with S. sobrinus during incubation at $37^{\circ}C$ for 24h were decreased to below critical pH 5.5. Spending times from pH 7.0 to pH 5.5~5.0 were Glucose solution(less than 1h). Carbonated drink(3h), Fruit juice(5h), Cow's milk(8h) and Mixed drink(21h). Conclusions: These results show that some commercial drinks with S. sorbrinus have the possibility of tooth decalcification. Thus, it is suggested that the people who have the low salivary secretion rate and the children who sleep without toothbrushing after drinking need the instruction for diet control and oral health education.