[Salivary factors associated to the prevalence and increase of dental caries in rural schoolchildren].

Objective: To evaluate the association between saliva and prevalence of dental caries.

Methods: Two-year longitudinal study in rural schoolchildren at Cruz del Eje, Argentina between 2000 and 2002. The study population comprised all schoolchildren (N=196) aged 5 to 14 years of both sexes attending eight rural schools. They were assessed at three different time points (N=46): baseline, 12 and 24 months. Salivary components and DMFT and dmft indexes were used. Nominal variables, "decay" and "new decay", were created to assess risk of decay at baseline, 12, and 24 months, respectively. Principal component analysis was applied to select salivary factors associated to decay and then they were categorized according to the median as a cutoff value.

Results: High prevalence of decay (50%-90%) was found at the three time points of study. There was significantly increase in caries at 12 months (p=0.000) compared to that seen at 24 months. At baseline there were homogeneous low levels of calcium and phosphate and a significant association (p<0.050) between calcium and phosphorus and calcium/phosphorus molar ratio and decay.

Conclusions: Phosphorus levels and calcium/phosphorus molar ratio can be considered risk factors for the development of caries in populations with characteristics similar to those studied.