[Short dental implant biomechanics in the mandible bone tissue]

The aim of the study was to assess the stress-strain state of «short dental implant - lower jaw bone tissue» system in the its osseointegration area under different stress options, of an experimentally developed bone tissue model. Using the finite element analysis method, we investigated a three-dimensional model of an implant with 5.0 mm diameter and 6.5 mm height integrated into the quasi-elastic model of the lower jaw segment with a total deformation modulus of 14 400 MPa and a Poisson's ratio of 0.24 for the cortical layer, for the spongy layer, the general deformation module of 0.2 MPa, Poisson's ratio 0.4. The values of equivalent stresses according to the Genki-Mises criterion for the implant body amounted to 50-76 MPa in the cervical region from the end and inner sides of the implant interface and along the upper edges of the thread edges in the upper third of the implant. Minimum values of 0.1-20 MPa are distributed over the implant body from its cervical part to the top in the lower 2/3. The equivalent von Mises stresses in the bone at the joints of the threaded implant part are minimal - 5-15 MPa. Values of shear stresses in the bone - 2 - 3 MPa, normal vertical stresses - up to 5-13MPa, main tensile stresses - up to 20 MPa, compressive stresses - up to 30-40 MPa. Thus, installing this implant in such model, should not occur irreversible deformations. In our opinion, the structural stability is ensured by the bone tissue features architectonics within 3 mm of the cortical layer, where the maximum stress is redistributed in the future throughout the cortical bone, which can expand the indications for short dental implants use, especially in patients with a limited alveolar bone volume.