Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 11 6 2014 12 15 672 9 Mina Biria Associate Professor, Department of Pedodontics, Shahid Beheshti University of Medical Sciences, Shahid Beheshti Dental School, Tehran, Iran. Gita Eslami Professor, Department of Microbiology, Shahid Beheshti University of Medical Sciences, Shahid Beheshti Medical School, Tehran, Iran. Elaheh Taghipour Pedodontist,Tehran, Iran. Alireza Akbarzadeh Baghban Associate Professor, Department of Basic Sciences, Faculty of Rehabilitation Sciences,Shahid Beheshti University of Medical Sciences,Tehran, Iran. 2015 10 16 In the recent years, herbal oral hygiene products have gained increasing attention. The aim of this study was to assess the effects of three types of mastic gums on the level of Mutans streptococci, Lactobacilli and pH of the saliva.Forty-two students in the age range of 20-30 years were divided into three parallel groups; each of them separately used pure mastic gum, xylitol mastic gum and probiotic mastic gum for three weeks. Number of microorganisms and pH of the saliva were assessed before and after the intervention. The data were analyzed using Wilcoxon Signed Rank, paired-sample-t, Kruskal-Wallis and Tukey's post-hoc tests and Oneway ANOVA.Level of Mutans streptococci showed a significant reduction compared to its baseline value in all three groups (P https://fid.tums.ac.ir/index.php/fid/article/view/399 https://fid.tums.ac.ir/index.php/fid/article/download/399/375