Flow rate and composition of whole saliva in children from rural and urban Thailand with different caries prevalence and dietary intake.

The aim of this study was to compare the prevalence of dental caries, dietary composition and whole salivary flow rates together with some of the components of saliva between two groups of children aged 12-16 years, one group from an urban area and the other from a rural area of Thailand. A stratified random samples were taken by class from one schools in each area. The children who had mixed dentition and/or who had migrated from other area of Bangkok and 138 students were selected from a school in a rural area of Khon Kaen in northeast Thailand. Results of completed 24-hour dietary recalls for three consecutive days examining the average nutrient intake were compared looking for differences, if any, between these two groups of children. Dental examinations and whole salivary sampling were also undertaken and possible relationships between some nutrients and certain salivary factors were explored. The prevalence of dental caries was found to be higher in the students living in the urban area. The children in the rural area consumed a higher load of carbohydrate, which came mainly from sticky rice. There was no difference in the protein consumption between the two groups, although the children in the rural area consumed more protein from vegetable sources. The salivary flow rate and the concentrations of fluoride, calcium and phosphate were significantly higher (p < 0.05) in the group from the rural area, while the salivary pH, buffer capacity, concentrations of total protein and urea were higher in the urban area. There was no correlation between nutrient intake and salivary composition in the children from these two areas, which may suggest that dietary nutrients may not have a direct effect on salivary compositions but it was noted that salivary flow rate correlated with salivary urea, albumin and buffer capacity in both areas.