Study design
The study was approved by the Ethic Committee of Faculty of Dentistry, Prince of Songkla University. Subjects or their parents were informed consent to participate the study. The prospective investigation had a double blinded randomized placebo controlled study design. The Subjects were divided into two groups by a randomized sampling , 13 subjects in study group (8 females, 5 males, mean age 18.77± 4.42 years ) and 15 subjects in control group (11 females, 4 males, mean age 19.4± 3.11 years ). The study group would receive probiotic milk and the control group received control milk. All subjects were advised to intake the received milk at breakfast time for 30 days. No tooth brushing was allowed for at least 1 hour after milks consumption. During the experimental period, the subjects were strongly encouraged to maintain their normal diet, no took others probiotic products and continue to brush their teeth twice a day.