pH and bacterial profile of dental plaque in children and adults of a low caries population.

OBJECTIVE: This study compares pH and microbiological profile of dental plaque in children and adults of a low caries population. MATERIAL AND METHODS: Thirty-nine children, 12-14 years of age and 45 adults between 20 and 39 years of age in 5 Karen villages of the Tak province, Northern Thailand were examined for plaque, calculus, caries (DMFT) and pH measurements in resting plaque and after a sucrose rinse. Information on dietary and oral hygiene habits was obtained through interviews using a fixed questionnaire. Microbiological profile of plaque samples was analyzed with DNA-DNA checkerboard technique. RESULTS: Mean DMFT was 0.77 +/- 1.56 and 87% of the adults and 67% of the children were caries free (p < 0.05). The mean resting pH was for both age groups in the range of 7.0-7.1 and significantly higher than a Swedish caries free reference group. Karen adult men had significantly lower pH minimum than females and children (p < 0.05). Supragingival plaque samples showed high levels of low acidogenic and anaerobic species, which dominated over strong acid producers such as streptococci. CONCLUSION: The study indicates that the Karen children and adults has a plaque physiology and microbiology predominating by low acidogenic anaerobes, which in addition to the low sucrose intake explains the low caries prevalence in this population.