Investigation of the stresses caused by zygomatic, dental and pterygoid implants applied with different plans in bilateral atrophic maxillary rehabilitation by finite element analysis

In implant-supported treatments of the highly resorbed posterior maxilla, the use of zygomatic bone as anchorage, sinus lifting, bone grafts, short and inclined implants, and pterygoid implants are among the alternative methods. The goal of zygomatic implants and pterygoid implants is to simplify the treatment of the excessively atrophic posterior maxilla, increase the success of surgical procedure results, reduce morbidity and procedure time, and avoid additional surgeries. However, due to limited accessibility, arranging these implants is technically more difficult than placing the implants from the maximum anterior region. The aim of this study is to examine the stresses that occur in the surrounding tissues and implants under the chewing forces of zygomatic, dental and pterygoid implants in the hyperatrophic maxilla modeled with computer aid by finite element analysis method and to select the most accurate treatment planning by evaluating the data obtained. A total of 4 different models were prepared in our study. In group 1, a dental implant was placed in the premolar tooth area in addition to the right and left zygomatic implants, in group 2 a dental implant was placed in the lateral and premolar tooth area in addition to the right and left zygomatic implants, in group 3 a dental implant was placed in the premolar tooth area in addition to the right and left pterygoid implants, and in group 4, a dental implant was placed in the lateral and premolar tooth area in addition to the right and left pterygoid implants. In our study, zygomatic implants (Nobel Biocare Zygoma implant) were 4 mm in diameter and 35 mm in length, dental implants (Nobel Biocare Active implant) were 3.5 mm in diameter and 10 mm in length, and pterygoid implants (Nobel Branemark Mk 3 Groovy Pterygoid implant) were 4 mm in diameter and 15 mm in length. A vertical force of 150 N and an oblique force of 100 N were applied to the tooth areas numbered 2-4-6-7 at a 30 degree angle. In the analysis on the effects of the forces used in the study, the Von Mises stress values in the implants and metal substructures and the maximum and minimum stress values in the alveolar bone were examined by finite element stress analysis. In our study, it was observed that the stress values in group 2 and group 4 were lower than the stress values in group 1 and group 3, and the highest stress accumulation occurred in group 3 and the least in group 2. As a result of this study, it was concluded that the stress that occurred as a result of the increase in the number of implants placed decreased. Key words: Atrophic maxilla, pterygoid implant, finite element stress analysis