Biomechanical Analysis of Implants Placed in Grafted Maxillary Sinuses

Objectives: Maxillary sinus bone graft augmentation has become one of the most common methods for increasing bone volume for implant placement in the posterior atrophic edentulous maxilla. In this study, we analyzed the microstrains around an implant in resorption and non-resorption models with different graft qualities. Methods: A three-dimensional finite element model of an osseointegrated implant placed in grafted maxillary sinuses was performed to compare the microstrain distribution in a non-marginal bone loss (MBL) model with those in four models with MBL of two depths (1.3 and 2.6 mm) and two types (angular and horizontal). The graft quality (high, medium, and less stiff) was varied in the models to simulated different clinical scenarios. Oblique functional loading was applied to the restoration on osseointegrated implant. Results: The distributions of microstrains in grafted bone were higher in the MBL models than those in the non MBL. Bone strain distributions were slightly higher in the horizontal MBL models than those in the vertical MBL. Over all models, the analysis showed that the microstrains of the less stiff grafted material under average chewing forces fall into the overload or pathologic load window according to Frost's Mechanostat Theory. Conclusion: The results of this analysis suggest that MBL around osseointegrated implant that is placed in a posterior edentulous maxilla with a sinus graft as well as the stiffness of grafted bone may be the result of the bone biomechanical adaptation.