Effect of salivary components on dissolution rates of carbonated apatites

Salivary pellicle has been reported to retard the acid-induced demineralization of dental enamel. However, this effect has not been quantified, nor has the direct protective effect of pellicle on carbonated apatite dissolution been elucidated. We have developed a model capable of further studying these questions. Well-characterized synthetic ceramic carbonated apatite discs were pretreated with parotid or whole salivary secretions for 18 h or 7 days and then challenged with 0.1 mol/l acetate, pH 5.0, in a dissolution apparatus. Surface dissolution rates were compared to those from the same carbonated apatites with no saliva pretreatment. Pellicles formed from whole and parotid saliva in vitro and whole saliva in vivo were capable of reducing surface dissolution rates of ceramic carbonated apatites by up to 83% but the degree of this reduction was dependent on the type of saliva and the conditions of pretreatment.