The examination of stresses created in environmental tissues of zygomatic and dental implants applied combined, the dental implants that are applied with "All-On-Four" technique and the subperiosteal implants (AMSJI) in bilateral atrophic maxilla by finite element analysis

In severily atrophic posterior maxilla, there is usually not enough bone to apply a conventional dental implant. Dental implants applied with "all-on-four" technique, zygomatic implants and superiostal implants (AMSJI) have been preferred frequently in recent years because they eliminate the need for grafting, shorten the treatment period and reduce the morbidity rate. A model showing atrophy in bilateral posterior maxilla was obtained by using computerized tomography records in our study. The aim of our study is choosing the most accurate surgical planning to this model according to stress values resulting from forces applied to zygomatic and dental implants applied combined, dental implants applied with all on four technique and subperiostal implants (amsji). Three group model was created in our study. In group model 1, a dental implant (Nobel Biocare AB, Goteborg, Sweden) was applied to both right and left sides of canine area and to the second premolar tooth area each, using "all-on-four" technique. The anterior implant was applied to the canine tooth area with diameter of 3.75 mm and with a length of 11.5 mm vertical angle, the posterior implant was applied to the second premolar tooth area with a diameter of 3.75 mm, a lenght of 13 mm with 30º angle. In group model 2, a dental implant was applied to each side of the canine tooth area with the diameter 3.75 mm and the length of 11.5 mm with vertical angle, one zygomatic implant (Nobel Biocare AB, Goteborg, Sweden) with a diameter of 4 mm and a length of 35 mm using the extrasinus technique at an angle of 45º degree to the first molar area was applied. In group model 3, left and right subpreriostal implant was applied. A vertical force of 150 N and an oblique force of 100 N at an angle of 30º degrees were applied from the area of teeth 4-5-6 on the prosthetic upper structure. As a result of the forces applied in the study, Von Mises stress values occuring in zygomatic, dental and subperiostal (AMSJI) implants and metal infrastructure, maximum and minimum stress values occuring in the maxillary alveolar bone and zygomatic bone were examined by finite element stress analysis. According to the results of our study, the maximum and minimum principal stresses in the alveolar bone and the Von Mises stresses in the metal infrastructure were observed the least in group 3. The stress values observed in the alveolar bone under vertical forces, maximum and minimum, and in all parameters under oblique forces were determined mostly in group 1. Based on these results, it was concluded that the most ideal planning in bilateral atrophic maxilla is subperiosteal implants (AMSJI).