Methods: This investigation was part of a single-blind, cross-over design study that tested experimental and placebo dentifrices. Subjects (n=38) wore palatal appliances, loaded with bovine enamel specimens. They were instructed to simulate toothbrushing with the dentifrices followed by exposure of specimens to orange juice for 10, 20 and 30 min. Surface microhardness of enamel was measured before and after the clinical phase and the %SMC calculated for each demineralization time. Subjects had samples of saliva collected and analyzed for volume, pH and buffering capacity, concentrations of calcium, phosphate and fluoride, and Ca/P ratio. The results from the saliva analyses were compared to the %SMC results obtained with the placebo treatment, to explore any possible relationship between salivary composition/properties and enamel demineralization pattern.
Results: Multiple-variable linear regression models tested were not statistically significant and could not explain more than 20% of the variability in the SMC outcomes. Phosphorus concentration was significantly negatively associated with SMC1 (R2=0.12, p=0.03). Ca/P was marginally positively associated with SMC1 (R2=0.10, p=0.06). Buffer capacity was marginally negatively associated with SMC2 (R2=0.08, p=0.09). No other significant individual factor association to SMC was found.
Conclusion: Individual differences on the properties and chemical composition of saliva proved to be irrelevant explaining the differences observed on enamel demineralization, for the population studied. Further investigation on the organic composition of saliva should be pursued, in order to better understand variations on enamel demineralization pattern. Sponsored by GSK.