Analysis Of Stress In Fixed Prothesis Of Maxillary Edentulous Jaw For Pterygomaxillary Implanting Design

Background Implant fixed prosthesis has incomparable advantages compared with traditional removable denture.It has been successfully applied to the restoration of dentition defect and dentition loss.Scholars at home and abroad have different opinions on the implant design of edentulous patients.For maxillary edentulous patients,owing to the limitation of anatomical condition,the maxillary posterior teeth cannot be designed for conventional implant because of the severe bone atrophy.All-on-Four technology has become an alternative method for edentulous patients with limited occlusal force and large cantilever.For young patients with large maxillary arch,it is easy to cause cantilever fracture.In order to overcome these limitations,some scholars have proposed the pterygomaxillary planting(TPP)technology,which appeared almost at the same time as the zygomatic planting,but has not been well developed.Recently,many scholars have tried to make up for this defect by combining TPP technology with All-on-Four design,but its long-term effect has not been confirmed.TPP technology is highly sensitive,and the current evidence-based medical literature on pterygomaxillary implantation is insufficient.It is necessary to form a better regularity summary in theory,such as implant angle,relationship with anatomy,mechanical analysis and so on.Objective: To study the variation of stress distribution of implants and bone tissues in fixed prothesis of maxillary edentulous patients for pterygomaxillary implanting design by applying three dimensional finite element method.Method: A total of 6 implants(No.1~No.6)are designed from right to left in maxillary of edentulous patients,and six sets of models are respectively established by fixing the implanting position,changing the number of implants and inclining the implanting angle.300 N static force is applied vertically to the functional cusp of bilateral posterior teeth,then the Mises stress on the surface of implants and bone tissues is calculated by utilizing Abaqus6.13 finite element analysis software,and statistical analysis is performed on the data with Spss21.0 software package.Result: Two pterygomaxillary implants are added while keeping the implanting angle of four middle implants unchanged,and the stress on No.2~No.5 implants is reduced significantly and distributed symmetrically and uniformly.In the case of keeping the number of implants unchanged,the stresses on the surface of implants and bone tissues are respectively altered by 3.25% and 5.08% through changing the implanting angle of distal implants,and the difference of maximum stresses on the surface of implants and bone tissues is not statistically significant(P>0.05).Conclusion: Pterygomaxillary implanting design can well disperse and transmit stress and make the stress on the surface of implants and bone tissues be distributed more reasonable,therefore it’s regarded as a reasonable and effective method for the implant restoration of maxillary edentulous jaw patients.