CLINICAL AND EXPERIMENTAL ARGUMENTATION OF MODIFIED METHOD FOR PERI-IMPLANT BONE REDUCTION EVALUATION DURING VARIOUS SCHEMES OF PROSTHETIC REHABILITATION

Peri-implant bone loss is circular and volumetric by its main features, but in the most of researches level of bone reduction is measured via two-dimensional approach from the medial and distal sides of the implant structure. The effectiveness of this approach have been well documented by the significant number of scientists and clinicians, but the research of algorithm that provides specification of changes in the hard tissue around the established titanium element remains topical issues of modern implantology. So, the aim of the paper was to determine the possibility of registering peri-implant bone changes through 9-12 months after the fixation of definitive prosthetic restorations in the system of non-removable implant supported prosthetics and system using full and partial overdentures as superstructures and supported by the implants. Evaluation process was held by the principle of image superimposition. Another objective of our study was to analyze the feasibility of the modified approach for determination volumetric loss of hard tissue due to the influence of artifacts on the quality of the tomographic slices. In order to determine peri-implant bone changes was used a modified algorithm of images superimposition which includes converting of each patient’s pairs of .dcm files to .stl format with further fragmentation zones of interest with a radius of 1 cm around each dental implant. Overlaying process of received fragments were held in adapted graphics software MeshLab by combining structured surface superimposition with the relevant points of comparison. Circular definition of bone changes was highlighted by color difference for each of the analyzed objects, after which was conducted calculation of conventional parameters corresponded to the volumetric reduction of bone. Bone tissue as an object of research and superimposition of tomographic evaluation results, is unique in terms of analysis capacities that by its structure allows the efficient use of surface parameters and the voxel characteristics algorithms for image overlaying. Using the superimposition principle of computer-tomographic studies made immediately after implants installation and in the 9-12 months of prosthetics functioning provides opportunities to identify indicators of peri-implant bone changes considering the circular nature of the bone crest reduction and its volumetric nature of resorption. The obtained data allow to individualize the approach of assessing the quality of complex iatrogenic interventions conducted with the ability to analyze the impact of various factors on peri-implant bone changes, including the adequacy of choosing specific schemes of prosthetic rehabilitation of dental patients supported by implants structures