Anchorage effect of various shape palatal osseointegrated implants: a finite element study

The purpose of this study was to compare the anchorage effects of different palatal osseointegrated implants using a finite element analysis. Three types of cylinder implants (simple implant, step implant, screw implant) were investigated. Three finite element models were constructed. Each consisted of two maxillary second premolars, their associated periodontal ligament (PDL) and alveolar bones, palatal bone, palatal implant, and a transpalatal arch. Another model without an implant was used for comparison. The horizontal force (mesial 5N, palatal 1N) was loaded at the buccal bracket of each second premolar, and the stress in the PDL, implant, and implant surrounding bone was calculated. The results showed that the palatal implant could significantly reduce von Mises stress in the PDL (maximum von Mises stress was reduced 24.3-27.7%). The von Mises stress magnitude in the PDL was almost same in the three models with implants. The stress in the implant surrounding bone was very low. These results suggested that the implant is a useful tool for increasing anchorage. Adding a step is useful to lower the stress in the implant and surrounding bone, but adding a screw to a cylinder implant had little advantage in increasing the anchorage effect.