A 3-dimensional finite element analysis of tapered internal connection implant system (Avana SS III(R)) on different abutment connections / 대한치과보철학회지

PURPOSE: The purpose of this study was to compare the stress distribution characteristics of four different abutment connections on SS-III(R) fixture under occlusal loading, using 3-dimensional finite element method. MATERIALS AND METHODS: The fixture of SS-III(R) (Osstem, Korea) with 4 mm diameter and 11.5 mm length and 4 types of abutments were analyzed; Solid, Com-Octa, ComOcta Gold, and Octa abutment. The models were placed in the area of first molar in the mandible. The 4 loading conditions were; (1) the vertical loading of 100 N on the central fossa, (2) the vertical loading of 100 N on the buccal cusp, (3) the 30degreesinclined loading of 100 N to lingual side on the central fossa, and (4) the 30degrees inclined loading of 100 N to the lingual side on the buccal cusp. The 3G.Author program was used, the von-Mises stress was calculated and the stress contours were plotted on each part of the implant systems and the surrounding bone structures. RESULTS: Regardless of abutment types and loading conditions, higher stress concentration was observed at the cortical bone. In cancellous bone, the highest stress was observed at apical portion and the maximum stress occurred at the implant neck. The higher internal stress was observed in the fixtures than in the bone. The lowest stress was observed at loading condition 1 and the stress concentration was also lower than any other loading conditions. CONCLUSION: Within the limitation of the result of this study, it seems that the abutment connection type does not affect much on the stress distribution of bone structure.

Three-dimensional finite element analysis on stress distribution of the mandibular implant-supported cantilever prostheses depending on the designs / 대한치과보철학회지

STATEMENT OF PROBLEM: The position and length of cantilever influence on the stress distribution of implants, superstructure and bone. In edentulous mandible, implant-supported cantilever prostheses that based 4 or 6 implants between mental foramens has been attempted. Excessive bite force loaded at cantilever prosthesis causes bone resorption and breakage of superstructure prosthesis around posterior implants. To complement the cantilever length of conventional prosthesis, In 1992, (McCartney) introduced "cantilever - rest - implant" and Malo reported "All-on-Four" in 2003. PURPOSE: Analyze and compare the stress distribution of conventional cantilever prostheses with rest implant and Allon-Four(TM) implant prostheses. MATERIAL AND METHOD: The external loads (300 N vertically, 75 N horizontally) are applied to first molar area. The stress value, stress distribution and aspect of stress dispersion are analyzed by three-dimensional finite element analysis program, ANSYS ver. 10.0. RESULTS: 1. The rest implant and "All-on-Four" implant system are superior to conventional cantilever prostheses to reduce stress on the bone and the superstructure around implants. 2. The rest implant was of the greatest advantage to stress distribution on bone, implant and superstructure. 3. With same number of implants, distally tilted implants are preferred to conventional cantilever prostheses for reducing the length of cantilever.