Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 29 1-4 2000 06 15 71 76 P. Owlia MH. Salari H. Saderi Z. Kadkhoda 2015 10 03 In this study 100 cases of advanced periodontitis were compared with a control group of 100 persons. The parameters were the depth of the periodontal pockets, radiographic images, presence of inflammatory cells and different types of anaerobic bacteria in the pockets. The depth of pocket was measured by a sterile probe and the presence of inflammatory cells was determined through sterile curettage. The smears were stained by Gimsa and Gram methods. For the purpose of microbiological studies, subgingival plaque samples were taken on paper points and were plated on brucella agar medium supplemented with rabbit blood, haemin and vitamin K1. The results indicated that with increasing depth of the pocket, the number of mixed anaerobic infections increases, and the presence of inflammatory cells especially polymorphonuclears is more prominent in comparison to the control group. As the pocket depth increases the conditions become more favourable for anaerobic bacteria and in consequence the incidence of isolation of these bacteria increases. On the other hand as the number of anaerobic bacteria and inflammatory cells and the secretion of destructive enzymes increases, the resultant injury to periodontal tissue increases. https://ijph.tums.ac.ir/index.php/ijph/article/view/1715 https://ijph.tums.ac.ir/index.php/ijph/article/download/1715/1696