The purpose of the study was to evaluate the effectiveness of the proposed treatment based on changes in radiological parameters in patients with destructive forms of apical periodontitis in the long term. Materials and methods. During the study, 185 patients with destructive forms of apical periodontitis were examined and treated. They were divided into 4 groups. Measurements of the size of the lesion in the bone tissue (for lesions of round shape) were performed by the formula: S = πr2; for lesions of elliptical shape: S = π ab, where π = 3.14; r – the radius of the circle; a – the value of the major half-axis of the ellipse; b – the length of the small half-axis of the ellipse. Results and discussion. When evaluating X-rays pictures in the treating group IV, where ("Platelet-Rich Plasma + mp3 OsteoBiol") was used for root canal obturation, after 6 months of observation, in 19 people (40.43%) foci of destruction of the bone tissue of the apical area of 1.5 mm2 and less were visualized. It was characteristic of this group of persons that there was a decrease in their number of bone tissue destruction area in sizes: 1.6 - 20 mm2 – by 1.7 times; 21 - 30 mm2 – by 2.0 times; 31 - 40 mm2 – by 2.5 times; 41 - 51 and more mm2 – by 1.3 times. It should be noted that this trend convincingly demonstrates a significant reduction in bone tissue of the periapical area in patients of group IV, and indicates in favor of the adequacy of the applied therapy using our proposed osteotropic composition. X-ray evaluation of the results of treatment of patients of group IV, in whom for the treatment of destructive forms of apical periodontitis our proposed composition ("Platelet-Rich Plasma + mp3 OsteoBiol") was used, after 12 months of research showed that in 29 patients (61.70%) foci of destruction of the apical area were not visualized; in 14 people (29.79%) the foci of osteoporosis bone tissue in the apical area were 1.5 mm2 or less. At the same time, no lesions ranging in size from 1.6 mm2 to 30 mm2 were identified in the treated group IV. At the same time, we determined a decrease in the number of treated with lesion areas: 31 - 40 mm2 – by 2.0 times; 41 - 50 mm2 – by 3.0 times and 51 mm2 and more – by 1.5 times. After 12 months of follow-up in patients of group IV, Rtg score of bone destruction was 4.27±0.61 points, which was probably higher than in patients of I, II, p, p1 <0,01, and III study groups, p2 <0.05. It was noted that at the areas of destruction of cell tissue of the periapical area from 1.6 mm2 to 30 mm2, Rtg score with a value of 5.0±0.71 points, indicated a complete restoration of bone structure; from 31 mm2 to 50 mm2 – for the reduction of the periapical process more than 1/2 and for the area of 51 mm2 and more – for the reduction of the periapical process from 1/3 to 1/2