Zub H. Optimization of treatment and prevention of complications in mandibular fractures in children

The dissertation presents a solution to a pressing scientific problem, which is to increase the effectiveness of surgical treatment of mandibular fractures in children and prevent complications by optimizing the osteosynthesis technique, determining safe zones and fixation points of miniplates taking into account age-related anatomical features, and developing a computer program for planning surgical intervention. At the first stage of the retrospective study, we analyzed 253 computed tomograms of the mandible without a fracture in patients aged 1-17 years in order to determine safe zones for fixation of miniplates and screw drilling points that hold them in the surgical treatment of mandibular fractures of various localization: 50 computed tomograms of children aged 1-5 years, of which 21 were girls (42%) and 29 were boys (58%), 101 tomograms of children aged 6-12 years, of which 44 were girls (43,6%) and 57 were boys (56,4%) and 102 computed tomograms of children aged 9-17 years, of which 39 were girls (38,2%) and 63 were boys (61,8%), as well as 27 computed tomograms of patients aged 10 - 17 years with mandibular fractures, of which 9 were girls (34,6%) and 17 boys (65,4%) and data from medical histories of children with mandibular fractures who were treated by osteosynthesis in the maxillofacial departments of city hospitals in Dnipro for the period from 2012 to 2022. When analyzing tomographic images of children aged 6 to 12 years, it was found that in 85% of cases the mandibular fracture passed through the roots of the first permanent premolars or molars, as well as through the rudiments of the second permanent premolars or molars. In addition, in all studied cases, the location of the mandibular canal was as close as possible to the fracture line. At the second stage, we studied the stress-strain state of the fixing plates, the screws that hold them, and the lower jaw itself in the area of its fracture on a three-dimensional finite element model with different options for the localization of its fractures, and justified the choice of optimal fixation of bone fragments on a mathematical model, and also developed an algorithm for the location of miniplate fixation using a computer program. The third stage of the study was devoted to assessing the prognostic value of promarker proteins in predicting the development of early inflammation in patients with mandibular fractures undergoing surgical treatment by osteosynthesis. The main attention was focused on the dynamic study of the concentrations of promarker proteins of inflammation in the oral fluid of children with the aim of early diagnosis of inflammatory complications and prediction of the course of reparative processes. At the fourth stage of the study, a clinical assessment of the effectiveness of the optimized osteosynthesis technique in the treatment of mandibular fractures in children was conducted. The technique was based on an individualized approach to the selection of “safe” zones for miniplate fixation and the optimal depth of screw immersion, taking into account the patient’s occupation and the anatomical localization of the fracture. The improvement of the technique became possible thanks to a comprehensive analysis of the results of biomechanical modeling (including finite element analysis of the stress-strain state of the fixing elements and bone), empirical threshold analysis of the depth of screw immersion, as well as assessments of the influence of age on the anatomical parameters of the lower jaw using regression models. These results were integrated into the algorithm for determining the optimal fixation points of miniplates, which was implemented in the form of a computer program for clinical use. New approaches to the selection of safe zones for osteosynthesis have been developed, which take into account the age and anatomical features of patients. The proposed orientation system allows for reliable stabilization of fragments even in complex fractures, minimizing the risk of damage to the growth zones and rudiments of permanent teeth, avoiding deformations during jaw growth, reducing immobilization and rehabilitation periods, and faster restoration of chewing and speech functions. Thus, the proposed osteosynthesis technique demonstrates high clinical effectiveness and safety, being a reliable and modern tool in the complex surgical treatment of mandibular fractures in children. Its implementation allows for significantly improving the quality of treatment, reducing the frequency of complications, and improving long-term functional and aesthetic results.