Finite element stress analysis of implant prosthesis according to connection types of implant-abutment / 대한치과보철학회지

PURPOSE: This study was to assess the loading distributing characteristics of implant systems with internal connection or external connection under vertical and inclined loading using finite element analysis. MATERIALS AND METHODS: Two finite element models were designed according to type of internal connection or external connection. The crown for mandibular first molar was made using cemented abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the centric cusp tip in a 15.inward inclined direction (loading condition B), or 200N at the centric cusp tip in a 30.outward inclined direction (loading condition C) respectively. Von Mises stresses were recorded and compared in the supporting bone, fixture, abutment and abutment screw. RESULTS: 1. In comparison with the whole stress of the model 1 and model 2, the stress pattern was shown through th contact of the abutment and the implant fixture in the model 1, while the stress pattern was shown through the abutment screw mainly in the model 2. 2. Without regard to the loading condition, greater stress was taken at the cortical bone, and lower stress was taken at the cancellous bone. The stress taken at the cortical bone was greater at the model 1 than at the model 2, but the stress taken at the cortical bone was much less than the stress taken at the abutment, the implant fixture, and the abutment screw in case of both model 1 and model 2. 3. Without regard to the loading condition, the stress pattern of the abutment was greater at the model 1 than at the model 2. 4. In comparison with the stress distribution of model 1 and model 2, the maximum stress was taken at the abutment in the model 1, while the maximum stress was taken at the abutment screw in the model 2. 5. The magnitude of the maximum stress taken at the supporting bone, the implant fixture, the abutment, and the abutment screw was greater in the order of loading condition A, B and C. CONCLUSION: The stress distribution pattern of the internal connection system was mostly distributed widely to the lower part along the inner surface of the implant fixture contacting the abutment core through its contact portion because of the intimate contact of the abutment and the implant fixture, and so the less stress was taken at the abutment screw, while the abutment screw can be the weakest portion clinically because the greater stress was taken at the abutment screw in case of the external connection system, and therefore the further clinical study about this problem is needed.

Three-dimensional finite element analysis on the effect of palatal vault shape on the stress distribution of edentulous maxilla surface / 西安交通大学学报(医学版)

Objective To study the effect of different palatal vault shape on the stress distribution of edentulous maxilla surface.Methods Using three-dimensional finite element method(3-D FED),we simulated five bite states,putting five loading conditions on 3-D FED model of maxillary edentulous with three different palatal vault shapes.Results We obtained the stress value and multicolor picture of 3-D FE model.Labial frenal notch zone and alveolar ridge zone were the stress concentration zone of the maxillary edentulous with three different palatal vault shapes under five kinds of loading conditions.The deep palatal vault maxillary edentulous almost had the maximum stress values in labial frenal notch zone,palate zone and alveolar ridge zone,and upper edentulous jaw with palatal torus was the minimum.Conclusion Palatal vault shape can change the stress value of edentulous maxilla surface,but cannot change the stress distribution.Loading condition can change the stress distribution and stress value.