the effect of calcium pre-rinse on salivary fluoride after 900 ppm fluoride mouthwash: a randomized clinical trial.

calcium fluoride deposit during fluoride application. uptake and retention of fluoride by saliva depends generally on the concentration of calcium. in this study, the effect of calcium pre-rinse on salivary fluoride concentration after a 900 ppm fluoride mouthwash was investigated.this cross-over double-blind randomized clinical trial was conducted in a girls' dormitory in zahedan university of medical sciences, southeast iran. in this study, 42 female dental students were chosen using simple randomization. during the first phase, 21 subjects (group a) used fluoride rinse (f regimen) and the remaining (group b) used calcium pre-rinse followed immediately by fluoride rinse (ca + f regimen). in the second phase, participants rinsed using the mouthwashes not previously used. prior to each phase prophylaxis was performed and no fluoridated product was used during a two-week interval between the phases. salivary samples were taken immediately before (baseline), 1 and 12 hours after rinsing. the salivary fluoride concentration was determined using fluoride sensitive electrode. repeated measures anova was used for statistical analysis and the significance level was set at p<0.05.there was significant difference between fluoride concentrations at different time points (p< 0.001). significant differences were observed when the different time points of two regimens were examined. in contrast to this, the baseline before using f regimen and the baseline before using ca + f regimen did not show any significance (p= 0.070).pre-rinsing with calcium before fluoride is recommended because of significant increases in salivary fluoride concentration.