Objectives. Traditional mechanic analysis of zirconium prosthesis does not give any biologic information about periodontal aspects. Observation of periodontal conditions is necessary in order to describe the relationship between zirconium crowns and periodontal tissues. The aim of the work is to evaluate the periodontal effects of zirconium prosthesis in comparison to metal-ceramic crowns. Methods. In the study group, 45 zirconium crowns are applied on 27 patients. Among them the prosthesized elements are: 15 central incisors, 12 lateral incisors, 8 canines, 6 first premolars and 4 second premolars. In the control group, 45 metal-ceramic elements are evaluated: 6 central incisors, 8 lateral incisors, 8 canines, 15 first molars e 8 second molars. Periodontal evaluations such as plaque index, bleeding, gingival recessions and periodontal probing are performed for each element. Results. The comparison of the two groups shows that the study group has a higher percentage of elements with 0-plaque index and elements with absence of bleeding. The study group also presents a lower incidence of gingival recessions and a lower probe depth in comparison with the control one