Evaluation of Stress Distribution on Distal Implant in Patients with All-on-Four System Planned by Finite Element Analysis
Project no. 25224 · Status: Kapanmış · 2022
Summary
<p><strong>Objective:</strong> As a result of resorption in the mandibles, the vertical bone height between the inferior alveolar nerve and the crest may become inadequate for dental implant placement. Bone regeneration methods, bone distraction procedures, horizontal or vertical augmentations, crest split or bone expansions may be needed to provide this required bone volume. As a result of these procedures, treatment time and costs increase. A technique called "All-on-four" has been developed to allow the use of fixed prosthesis in such patients. In this technique, 2 implants placed vertically in the anterior region in interforaminal area and 2 implants placed distally inclined at angles that can increase up to 45 degrees are used in the posterior region. The aim of our study is to evaluate the amount of stress caused by posterior angled implants on bone, implant, abutment, gingiva and prosthesis. Furthermore a sloped implant was used in addition to the standard implant.</p><p><strong>Materials/Methods: </strong>Using Ansys Workbench (ANSYS Inc. Houston, PA, USA) software, a 3D (solid) implant model of Medentika®(MEDENTiKA GmbH, Hügelsheim, Germany) with a length of 13 mm and a diameter of 4.3 mm with a 30-degree sloped and a straight 3D (solid) implant model with a length of 13 mm and a diameter of 4.3 mm was prepared. In addition, it was placed to the edentulous mandible model with in the D2 bone structure at 15, 30, 45 degrees in the distal direction and 30 degrees for the sloped implant. Maximum and minimum principal stresses, von Mises stress distrubition and displacement of the prosthesis were measured by applying 200 N force. Our study was supported by the Ege University Scientific Research Projects Coordinatorship with project number 25224.</p><p><strong>Results:</strong> As a result of the applied force, the highest minimum principal stress value in the bone was observed in the 15 and 30 degree model(-37.7 MPa) and the lowest minimum principal stress value in the sloped implant (-30.5 MPa). The highest maximum principal stress value was observed in the sloped neck implant(8.79 MPa) and the lowest maximum principal stress value was observed in the 45 degree model(3.82 MPa). The maximum von Mises stress values in the neck region of the angled implants of the models were measured as 177 MPa in Model 1, 192 MPa in Model 2, 282 MPa in Model 3 and 305 MPa in Model 4 and the lowest value was observed in the sloped neck implant. The lowest von Mises stress value on the abutments was 225 MPa for the sloped implant. The maximum displacement on the prosthesis in the first molar region was measured in Model-2 (0.82 mm) and the minimum displacement amount was measured in Model 1 (0.69 mm).</p><p><strong>Conclusion:</strong> The stress values that occur under the applied functional loads are concentrated in the neck region of the implants in all models. As a result, it can be predicted that bone resorption and implant fractures will occur in the neck region. However, in the models in our study, all these values are within physiological limits. Furthermore, when the sloped neck implants were evaluated, it was seen that they had the lowest von Mises stress values compared to standard implants. We predict that supporting our study with in vivo and clinical studies will create more effective results.</p>