Goal of the research was determination of effectiveness of clinical application of MTA. The study covered 79 molars of 79 patients (46 lower and 33 upper molars). The perforated areas were closed with MTA. Perforations were localized in various sections of crowns of teeth (over-junction--12, under-junction--23, in furcating area--44). The conclusion is that successful application of MTA requires attentive and careful approach, similar to any innovative technology in practical dentistry. In the article authors considered treatment of two-root incisors. Endo-treatment of perforation in the furcating area was conducted. In the other cases treatment was conducted on 16 teeth, in which the perforated areas were localized at the aperture of medial root. The third case shows closing of the resorbed apical hole in 46 teeth. In all clinical cases MTA was applied. The results of this study suggest that MTA would widen the capacities of dentists in their everyday work--in the process of treatment of teeth with various perforations.