Pelekhan B. Substantiation of Choosing Implant-Supported Dental Prosthesis in Patients with Edentulousness.

The improvement of mandible edentulousness prosthodontic treatment consisted in mechanical and mathematical modeling of the dental prosthesis interaction with the mandibular bone tissue. Recommendations regarding the permissible level and distribution of the mastication load were developed based on the modeling. Analytical estimates of the implants and adjacent bone tissue tension were made; in particular, analytical dependences of equivalent tension in implants and bone tissue on the coordinates of the implants’ location and on the coordinates of the mastication load application were obtained. Electromyographic examination of mm. masseter dexter et sinister in groups of patients was performed at the stage of prosthodontic treatment planning, in 14 days, 6 months and 12 months after the fixation of dental prostheses. X-ray examination by performing cone-beam computed tomography was conducted before the treatment and 12 months after the fixation the dental prostheses. The average values of bioelectrical activity of the masticatory muscles constituted 584.0±17.4 μV on the right and 543.4±12.9 μV on the left during the test of maximum bite force in the patients of group IA at the stage of prosthodontic treatment planning. According to the analysis of the quantitative results of cone-beam computed tomography, the median indicators of bone tissue loss around all osseointegrated implants in group IA constituted 0.46 mm. The dynamics of biopotentials average values increase at maximum bite force test was at the level of 32.48% on the right (pd<0.001) and 34.75% on the left (pd<0.001) in 12 months after fixation. The dynamics of functional changes differed slightly in the patients of groups IIA and IIB according to the results of instrumental examination methods. In particular, an electromyographically recorded increase in mm. masseter dexter by 47.97% (pd<0.001) and mm. masseter sinister by 44.19% (pd<0.001) was noted in the patients with primary prosthodontic treatment of mandible edentulousness (group IIA) during the fixation of complete removable bar-retained dental protheses at maximum bite force in 12 months after the treatment. The results of cone-beam computed tomography in the patients of groups IIA and IIB proved the influence of artificial dentition length on the quantitative loss of bone tissue around intraosseous dental implants. The loss of bone tissue 0.85 mm in patients of group IIA and 0.71 mm in patients of group IIB confirmed the urgency of finding a solution to the problem of the influence of the application site of masticatory load on the lateral movements of the dental prosthesis, irrational for intraosseous supports. The dynamics of increase in the average indicators of the masticatory muscles bioelectric activity in the patients of group IIIA during the maximum bite force test was as follows: by 2.61% on the right (pd<0.001) and 3.85% (pd<0.001) on the left in 14 days; by 53.85% on the right (pd<0.001) and 61.84% on the left (pd<0.001) in 6 months after the fixation; by 66.52% on the right (pd<0.001) and 76.37% (pd<0.001) on the left in 12 months after the treatment. Similar tendencies in the indicators increase were observed in the patients of group IIIB during the maximum bite force test. In particular, an increase in average indicators constituted 61.63% on the right (pd<0.001) and 67.20% on the left (pd<0.001) in 12 months after the fixation of dental protheses. Normalization of the index indicators of the asymmetry of the muscles functioning with a reliable approximation of the values to the indicators of the control group individuals was noted in both groups of patients with fixed dental prostheses manufactured according to the improved method, namely Csfl constituted 1.062 [1.049-1.071] (pc>0.01) in the patients of group IIIA and 1.093 [1.049-1.071] (pc<0.001) in the patients of group IIIB in 12 months after the treatment. The study of the disclusion time was indicative for the assessment of the changes in the masticatory muscles function in case of the occlusal load. The decrease in the disclusion time dynamics by 54.5% (pd<0.001) in group IIIA and by 52.1% (pd<0.001) in group IIIB with reliable approximation of the data to the values of individuals in the control group was the most significant among the groups of the treated patients. Key words: edentulousness, mandible, masticatory muscles, implantological treatment, mechanics and mathematical modeling, complete removable dental prosthesis, dental implants, electromyography, computerized method of occlusion analysis, cone beam computed tomography, treatment efficiency. Branch-Medicine.