Evaluation of the Stress Levels of Different Implant Treatment Options in Extremely Atrophic Maxillae by Finite...

Bone resorption progresses in the alveolar ridge after tooth loss. In extremely athropic maxillae, treatment options include quad-zygoma implants, iliac bone augmentation with intraosseous implants, (the All-on-4 concept), Group-SUB periosteal implant. In this study, extremely atrophic maxilla was defined as an edentulous ridge with 3 mm crest thickness, 6 mm nasal base-crest distance, and 5 mm sinus floor-crest distance.

This study aimed to compare stress distribution of these protocols using finite element analysis.

In this study, analyses were performed using the finite element method A total of three groups were included in the finite element analysis, each representing a different treatment configuration applied to an extremely atrophic maxilla. The AOF (All-on-4) configuration consisted of four conventional implants placed in the canine and first molar regions following iliac bone augmentation, supporting a metal-ceramic prosthetic restoration. The ZYG (Zygomatic) configuration consisted of four extra-maxillary zygomatic implants (quad zygoma), with two implants placed in the canine region and two in the posterior region on each half of the maxilla, supporting a metal-ceramic prosthetic restoration. The SUB (Subperiosteal) configuration consisted of a subperiosteal implant framework supporting a metal-ceramic prosthetic restoration. For all three configurations, three-dimensional finite element models were generated based on standardized geometric reconstruction of an extremely atrophic maxilla. Implant positioning, prosthetic design, material properties, boundary conditions, and loading scenarios were defined according to previously published finite element modeling protocols, and identical modeling assumptions were applied to all groups to allow direct comparison. In this study, vertical occlusal force of 150 N and an oblique force of 50 N at a 30° angle were applied. In the models created, minimum stresses in the cortical bone and minimum and maximum principal stresses (P max) in the spongiose bone were observed. The Von Mises Stress values of the implants and abutments were analyzed.

Stress in the alveolar bone remained within the physiological limits of the bone. However, it was determined that Group-SUB created less stress on the alveolar bone than the other Groups. When the Von Mises Stress values on the implants and abutments were examined, it was determined that Group-AOF had the highest Von Mises Stress values, followed by Group-ZYG (and Group 3-SUB had the lowest Von Mises Stress values. When the stresses occurring in the prosthetic restoration were evaluated, similar results were observed.

Our data suggest that zygoma implants may reduce stress concentration in extremely atrophic maxillae; however, clinical validation is required.