• Raveewan Punya-ngarm D.D.S., M.P.H.
• Pornsri Patimanukaseam B.Sc. (Med.Tech.), M.Sc. (Biochemistry)
• Yuttana Punya-ngarm D.D.S., M.P.H., Ph.D. (Public Health Nutrition)

Objective To study the changes of salivary flow rate and pH after drinking of sugar-free and sweetened
green tea beverages.

Materials and methods The subjects were 50 healthy volunteers, 20-22 years old who had not taken
any kinds of medicines for at least 3 months. On day 1; resting saliva were collected for 10 minutes in
3 successive portions; from 0 to 1, 1 to 5 and 5 to 10 minutes respectively. The salivary flow rate was
calculated in ml/min and the pH was determined by pH meter (pH meter, IQ125, USA.). On day 2, 3
and 4; subjects drank 250 ml of demineralized water, sugar-free green tea and sweetened green tea by
straw and the samples were performed by the same procedure. The differences of the mean salivary
flow rate and pH between resting, after intake of water, sugar-free green tea and sweetened green tea
were analyzed by One-Way ANOVA and LSD at 95% confidence limit.

Results The means flow rate of resting, after water, sugar-free green tea and sweetened green tea
intake were 0.40±0.15, 0.41±0.15, 0.48±0.26 and 0.59±0.21 ml/min, respectively. The mean pH for
0-1, 1-5 and 5-10 minutes at resting were 7.20±0.40, 7.20±0.38 and 7.20±0.39, after water intake were
7.21±0.40, 7.20±0.38 and 7.19±0.38, after sugar-free green tea intake were 7.71±0.39, 7.42±0.38 and
7.41±0.49 and after sweetened green tea intake were 8.0±0.24, 7.65±0.26 and 7.49±0.46, respectively.
The mean flow rate and pH at resting and after water intake were not significantly different but the
mean flow rate and pH after sugar-free green tea intake were significantly higher than the mean flow
rate and pH at resting and after water intake (p < .05) while mean flow rate and pH after sweetened
green tea intake were significantly higher than every other samples (p < .05).

Conclusion Sweetened green tea beverage was capable to increase salivary flow rate and pH apparently
higher than the sugar-free green tea.

(CU Dent J. 2005;28:11-8)