Pavlish I. Validation for the use of minimally invasive dental implantation in the lateral parts of the mandible in case of bone deficiency.

The dissertation is focused on the problem of prosthetic rehabilitation of patients with complete or partial loss of teeth on the mandible with a bone deficiency in lateral regions. As a result of the mathematical modeling, it was concluded that the density of the spongy substance significantly affects the distribution of equivalent stresses. Also the results showed that the density of the spongy substance has less effect on the maximum values of equivalent stresses in the cortical layer of bone in the bicortical fixation in comparison with monocortically installed implants, which with a change in the density of the spongy substance from ρ = 1.0 to ρ = 0.4 increases by 14.2% only. There was no significant effect of cancellous bone density on the distribution of equivalent stresses in the implants and the adjacent bone when five bicortically placed implants were used in a similar situation. The increase in equivalent stresses in the cortical layer with decreasing bone density from ρ = 1.0 to ρ = 0.4 was only 0.7% and their maximum values did not exceed the strength limits at different loads. The results of X-ray examination showed that the course of resorptive processes in the marginal peri-implant bone is similar in patients of the main and control groups. Thus, during the first year of implant operation, the average vertical resorption was 0.719 ± 0.001 mm in the main and 0.763 ± 0.001 mm in the control group, and 0.12 mm in both experimental groups during the second year. To identify the features of osseointegration of implants, placed by our adapted minimally invasive technique, we measured the implant stability coefficient (ISC) by frequency resonance analysis using the device Osstel ISQ. The study was conducted in the main and control groups at the time of implant placement, after 3 and 12 months. Analysis of the average ISC in the dynamics of both the main and control groups showed a gradual increase over 12 months, by 5 uo (10.7%) and 7.5 (15.2%) respectively. This allowed us to conclude that the process of reparative and physiological regeneration after implantation in both the main and control groups of patients during the first year is accompanied by compaction of bone tissue around the implants, which is the main sign of osseointegration. We analyzed the indicators of ISC depending on its density to identify the features of osseointegration of implants in different types of bone tissue of both experimental groups. After analyzing the dependence of the primary stability index on bone density, it was found that they are directly dependent in both experimental groups. The maximum difference of ISC was observed between groups D3 and D1 and in the main group it was 9.71 uo (19.3%), and in the control - 14.95 uo (26.6%). Moreover, in the same bone types slightly higher values of the coefficient of primary stability were observed in bone D1 and D2 in patients of the control groups compared to the main, 6 uo (11.8%) and 3 uo (6.4%) respectively; and in bone D3 - these values did not differ. Based on this, it was concluded that in the main group, bone density had less effect on the primary stability of the implant than in the control, which confirmed the advantages of bicortical implant placement. Our results of clinical and radiological research methods in combination with the analysis of rates of osseointegration of implants by frequency resonance analysis and mathematical research allowed us to objectively confirm the effectiveness and feasibility of our adapted minimally invasive technique of dental implantation by the bicortical placement of non-detachable using a surgical guide in conditions of bone deficiency, its biomechanical advantages. Indications and basic conditions for the use of minimally invasive methods of dental implantation in the posterior areas of the mandible in the case of bone deficiency are determined. This made it possible to expand the possibilities of using minimally invasive methods of dental implantation in conditions of bone atrophy.