Abstract: Objective To analyze the effect of different numbers and different angles of inclined implants on the stress distribution of implants and bone tissue by three-dimensional finite element analysis under the condition of constant static force loading. Methods Six models with different inclined-angle implants which were named No.1-5 from right to left in edentulous maxilla were designed. The implant placement sites were fixed. Through the reverse engineering modeling method, the 3D CaMega optical 3D scanning system was used to scan the Bego implant and abutment entities. Finally, the obtained reverse feature parameters were constructed using forward modeling tools to construct a solid model of the implant and abutment. Model Ⅰ: No.1-5 implant axial tilted 0 degree; Model Ⅱ: No.1 and No.5 implant were distal tilted 30 degrees, the rest of the implants axial tilted 0 degrees; Model Ⅲ: No.1, 2, 4and No.5 were distal tilted 15 degrees, and the rest of the implants axial tilted 0 degrees; Model Ⅳ: No.1 and No.5 were distal tilted 30 degrees, No.2 and No.4 were distal tilted 15 degrees, and the rest of the implants axial tilted 0 degrees. Model Ⅴ: No.1, 2, 4 and No.5 were distal titled 30 degrees. Model Ⅵ：No.1, 5 were distal titled 30 degrees. No.2, 4 were miso titled 15 degrees. The stress of the implant surface and bone tissue surface was analyzed by loading 300 N load on the 15 teeth. Results Models of maximum stress values on the surface of No.1 implant were Ⅰ＜Ⅳ＜Ⅴ＜Ⅱ＜Ⅲ＜Ⅵ, and models Ⅱ to Ⅵ increased by 28.17%, 45.70%, 7.90%, 22.33%, and 57.04%, respectively, compared with model I. The maximum stress value on the surface of implant No. 3 was the highest in model Ⅰ, which decreased by 29.19%, 43.62%, 23.48%, 20.46%, and 16.44%, respectively. Based on the maximum Mise stress value of the surface of bone tissue No. 1 in model I, the surface stress values of bone tissue No.1 in models Ⅱto Ⅵ decreased by 10.12%, 58.22%, and 18.35%, respectively, and those of models Ⅴand Ⅵ increased 57.59% and 12.65% respectively. Conclusion In maxillary toothless jaw fixed prosthesis, the asymmetry adds the angle of the distal inclined implant, which is conducive to obtaining better stress distribution. The symmetrical distal inclination of the implant in the anterior dental area will significantly reduce stress on the surface of the dental implant and bone tissue, and will also reduce the risk of bone resorption in the anterior dental area and fixed denture fracture.

Key words: edentulous maxillary, 3D finite element analysis, incline implant, stress analysis