In present dissertation the scientific substantiation and practical solution to one of the urgent problems of the Maxillofacial Surgery is presented: improving the efficiency of treatment of patients with post-traumatic and postoperative defects of the mandible, by the use of advanced computer modeling methods and CAD/CAM technologies.
Defects and deformation of the facial skull, resulting from traumatic injury, surgeries, inherited defects, cancer and infection processes are associated with distinct aesthetic and functional deficits and often require complex multistage reconstructive s interventions. It is known that the main task of combine treatment of patients with mandibular defects is to restore the anatomical shape and function of the affected jaw. For this purpose, bone autografts, implants of titanium and other bioinert materials, implants, preformed plates, standard and customized fixators, tissue engineering equivalents and various techniques of bone plastics are used. These methods, however, are not effective in a significant percentage of cases, due to the extreme difficulty of restoring the anatomical shape of the affected bone, its topographic and functional relationships with surrounding structures. In recent years, significant interest among scientists and clinicians is attracted by the possibility to use virtual simulation, computer modeling and CAD / CAM technology in the surgical treatment of this category of patients. Thus, the use of patient-specific implants (PSI) manufactured on the base of CAD / CAM technology is considered as a modern alternative to traditional methods of bone grafting, which not only reduces the duration, stages, invasiveness and complexity of surgery, but also improves its results. Within the framework of the digital protocol of mandibular reconstruction in recent years, a large number of technical solutions have been proposed that may differ significantly from clinical, mechanical and biological points of view. The long-term results of their use often need the further investigations, and the number of randomized trials to study clinical efficacy remains limited. In mandibular defects with complex topography, the use of standardized approaches and algorithms do not allow to reproduce accurately the anatomy of the affected bone, and existing surgical and biological limitations. So, it requires consideration of clinical features and adaptation of the design to the existing situation. The present research was aimed at clinical, anatomical and biomechanical substantiation of advanced methods of modeling, manufacturing and intraoperative use of patient-specific constructions to increase the accuracy of anatomical structures restoration, improve functional results, reduce duration of treatment, and frequency of intra- and postoperative complications. In the course of our research we conducted a series of clinical and instrumental studies, as well as biomechanical experiments on simulated computer models to develop methodological approaches and optimize the design of PSI to replace mandibular defects, as well as to determine clinical efficacy and application limits. Material of the study included 60 patients with mandibular defects, treated at the Center for Maxillofacial Surgery and Dentistry of Kyiv Regional Hospital during the period 2015-2020 years. Age of the patients ranged from 16 to 82 years, and on average was 40,9 ± 14,6 years. Among all surveyed, men accounted for 40%. The causes of defects were: segmental or subtotal resections of the mandible for benign tumors - 41% and malignant neoplasms - 16.7%, high-energy trauma - 7%, malformations - 1.9%, osteonecroses of various origin - 16.7%, defects of mandibular ramus after the treatment of bone ankylosis - 16.7%. Defects spread to the frontal part of the mandible in 28.3% of patients, to the distal part of the body (on one or two sides) - in 80%, to the branch - in 77%. Defects localized within one site, were noted in 33.9% of cases, within 2 anatomical sites - 50%, within 3 and more anatomical sites - 16.1%.
