The Study Of The Biomechanical Stresses Distribution On The Dental Implants In The Posterior Maxilla

Objective: To investigate the characteristic of the biomechanical stresses distribution on the dental implant in the atrophic posterior maxilla, in order to achieve optimized surgical procedure yields the best bony support for dental implants.Methods: Five 3D-FE models were used to model the different surgical approach designs in the atrophic posterior maxilla by differences Of length of the implants ,bony quality,and the quantitatively different packing situations through sinus floor augmentation. A load of 100 N was applied in a vertical direction and a oblique direction by 450 inclined to the lingual side to the functinal cusps of the crown.The parameters of bio-mechanical distribution of stresses was collected: maximum Von Mises'stresses,maximum tensile stresses and maximum compressive stresses,then investigate the characteristics of the biomechanical stresses distribution by the color-coded figure.Results: Complete peri-implant packing during sinus floor augmentation procedure dramatically reduces peri-implant peak stresses and bone-implant interfacial stresses compared with the non-grafted model,especially when the load is in oblique direction.The stress levels increased obviously when the load is in the oblique direction compared with in the vertical direction. The final evaluation of the FE models showed :When the load is in oblique direction ,complete peri-implant packing reduced stresses(maximum Von Mises stresses; maximum tensile stresses; maximum compressive stresses)of the bone-implant interface in the cortical layer by 41%;38.8%;43% vs.the reference model (model 1).While the model without cortical bone(models 5) provided some clues as to the importance of bone quality. The stresses of correlative location increased by 10%;24%;6% vs.the reference model (model 1). The results indicate that more extensive peri-implant packing reduces implant intrabony stresses and stresses at the bone–implant interface.Conclusions:1.Complete peri-implant packing during sinus floor augmentation is essential to yield the best bony support for dental implants when the ridge height of the atrophic posterior maxilla is inadequate.2.The cusp inclination of the artifical tooth should be lowed to avoid lateral occlusion trauma when the superstructure is designed.3.In other cases,if the bone quality is favorable but the bone quantity is inadequate,some steps should be choiced to improve the bone support ability,such as bone core grafting containing a preintigrated implant,or subcomplete sinus floor elevation through a pericrestal approach.Even so,it still encounters risks of failure to let the implant support the superstructure alone under the exact conditions.More implants used together or combined the natural teeth to support are both good choices.