Soft-Tissue Simulation for Computational Planning of Orthognathic Surgery

Simulation technologies offer interesting opportunities for computer planning of orthognathic surgery. However, the methods used to date require tedious set up of simulation meshes based on patient imaging data, and they rely on complex simulation models that require long computations. In this work, we propose a modeling and simulation methodology that addresses model set up and runtime simulation in a holistic manner. We pay special attention to modeling the coupling of rigid-bone and soft-tissue components of the facial model, such that the resulting model is computationally simple yet accurate. The proposed simulation methodology has been evaluated on a cohort of 10 patients of orthognathic surgery, comparing quantitatively simulation results to post-operative scans. The results suggest that the proposed simulation methods admit the use of coarse simulation meshes, with planning computation times of less than 10 seconds in most cases, and with clinically viable accuracy.

Computer planning of the bone grafting on the upper jaw (sinus lift)

The authors presented the experience of using the computed tomography method for additional diagnostics, determining the volume of bone tissue, clarifying the topography of the anatomical structures in the area of the planned implantation, choosing the location and direction of the dental implants in the jaw, their number, size and axial orientation. The study was conducted in a group of 35 patients requiring orthopedic rehabilitation using the method of dental implantation. 13 patients underwent computer planning of sinus lift surgery. The features of the application of computed tomography are described in detail. The treatment plan and its clinical stages of one of the patients who needed the procedure for building bone tissue are presented in detail. Conclusions and recommendations are made that can be useful in the further use of computer tomography in dental implantation, which allows more accurate measurement of bone tissue volume when deciding to perform the sinus lift procedure, minimize traumatic effects, and shorten the rehabilitation process.

Glenoid vault perforation in total shoulder arthroplasty: Do we need computer guidance?

The proliferation of computer 3D simulation and computer-generated guides is aimed at minimizing perforation of the glenoid vault by glenoid pegs in shoulder arthroplasty, based on assumptions that perforation leads to worse outcomes by component loosening and potential failure. We evaluated outcomes of glenoid peg perforation testing the assumption that perforation produces worse results. Eighty-three shoulders underwent shoulder arthroplasty with pegged hybrid fixation (bone-ingrowth flanged central glenoid peg and peripheral cemented pegs) without precision signal injector guides or use of 3D planning software. Outcomes were determined by American Shoulder and Elbow Score and Oxford Shoulder Score. Fine slice CT determined the presence of vault perforation and the extent of lucent lines at the prosthesis–bone interface and bony morphology of the vault perforation. Follow-up was 46.7 months (24–99). Seven shoulders (8%) demonstrated perforation of glenoid vault. Bony ingrowth and cortical overgrowth occurred despite perforation, with no clinically significant differences in clinical or radiological outcomes in shoulders with and without glenoid vault perforation. None of these patients underwent revision surgery. Despite not utilizing computer planning and/or guides, 92% of implants did not perforate the glenoid vault. However, glenoid vault perforation in our series produced excellent outcomes with no increased risk of revision as a result of glenoid vault perforation.

PERSONIFIED BIOMECHANICS OF EDENTULOUS JAW WITH RESTORATION ON THE SCHEME OF “ALL-ON-4” AND WITH PARALLEL IMPLANTS

The technology of patient-specific computer planning of the restoration process of the edentulous mandible dentition using dental implants is considered. A model of the jaw and distribution of elastic modules by its volume are reconstructed from a computer tomogram. The model is supplemented with virtual implants and a model of the prosthetic structure and is passed on to the finite element complex, where the loading and supporting conditions are specified. Biomechanical analysis and comparison of two implant placement schemes (“All-on-4” and in parallel implants) is carried out for two types of loading that model biting and chewing.