Tukalo I. Optimization of dental prosthetics with conditionally removable structures on dental implants using digital diagnostic and planning methods

The dissertation is devoted to improving the effectiveness of dental rehabilitation of patients with partial and complete edentulism through the optimization of digital treatment planning and the refinement of methods for registering the spatial coordinates of dental implants. The study comprised a series of clinical, laboratory, and experimental investigations aimed at comparing different approaches to the digital transfer of the spatial position of intraosseous implant supports and evaluating their influence on the clinical effectiveness of prosthetic rehabilitation. The research included a retrospective analysis of 416 completed clinical cases of dental rehabilitation, laboratory and clinical evaluation of different intraoral scanning strategies, a survey of prosthodontists regarding the use of digital treatment protocols, and a comparative assessment of the clinical performance of conventional, hybrid, and fully digital methods for implant position registration. Clinical, radiological, laboratory, digital, mathematical, and statistical methods were employed to accomplish the objectives of the study. The retrospective analysis demonstrated that dental implants were used as prosthetic supports in 33.41% of all full-mouth rehabilitation cases. Analysis of treatment protocols revealed a predominance of hybrid digital–analog workflows in implant-supported rehabilitation (57.3% of cases). At the same time, 63.64% of the surveyed dentists still preferred conventional elastomeric impressions for full-arch implant-supported prosthetic rehabilitation, whereas only 36.36% routinely used digital impressions. The laboratory and clinical investigations demonstrated that the occlusal–lingual–buccal scanning strategy and the lingual–occlusal scanning strategy with prior locking of the initially scanned segment provided significantly lower registration errors than the circumferential and zigzag scanning strategies. The occlusal–lingual–buccal strategy exhibited a mean deviation of 58 ± 46 μm, which did not differ statistically from the results obtained with the modified lingual–occlusal approach. Photogrammetry demonstrated the highest overall accuracy among all investigated techniques, producing the smallest linear and angular deviations. Based on the combined analysis of intraoral scanning and cone-beam computed tomography (CBCT) data, the author developed a modified method for scan body registration incorporating a mathematical correction model for spatial coordinates. This approach effectively compensated for the accumulation of errors across long inter-implant distances inherent to intraoral scanning while simultaneously minimizing the systematic inaccuracies associated with CBCT. Clinical validation demonstrated that the use of intraoral scanning without additional correction was associated with an almost twofold increase in the frequency of functionally compromised implant prognosis compared with the proposed method, photogrammetry, and the analog–hybrid protocol. At the same time, the author’s modified scan body registration technique showed mechanical complication rates comparable to those observed with photogrammetry. A comprehensive multicriteria analysis integrating structural reliability of prosthetic restorations, functional performance, patient satisfaction, treatment time, and economic costs demonstrated that, after adjustment for resource consumption, the highest corrected integral effectiveness index was achieved by the proposed digital registration protocol. Although photogrammetry exhibited the highest metrological accuracy, its economic efficiency proved to be lower under routine clinical conditions. The obtained findings indicate that the proposed comprehensive digital protocol combining intraoral scanning, cone-beam computed tomography, and mathematical correction of implant coordinates improves the accuracy of prosthetic fabrication, enhances the passive fit of implant-supported restorations, reduces the risk of mechanical complications, and increases the overall effectiveness of dental rehabilitation in patients with partial and complete edentulism.