Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 4 2013 07 15 376 82 Nahid Ramazani Assistant Professor, Children and Adolescent Health Research Center, Department of Pediatric Dentistry, Faculty of Dentistry, Zahedan University of Medical Sciences, Zahedan, Iran. Rahil Ahmadi Assistant Professor, Department of Pediatric Dentistry, Faculty of Dentistry, Shahed University, Tehran, Iran. Zahra Heidari Professor, Genetic of Non Communicable Disease Research Center, Department of Histology, Medical School, Zahedan University of Medical Sciences, Zahedan, Iran. Arezoo Hushmandi Dentist, Zahedan University of Medical Sciences, Zahedan, Iran. 2015 10 16 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 https://fid.tums.ac.ir/index.php/fid/article/view/626 https://fid.tums.ac.ir/index.php/fid/article/download/626/601