[Stress distribution of two kinds of fixed prosthese supported by four or six dental implants in edentulous mandible].

PURPOSE

To investigate the stress distribution of 2 kinds of distal cantilevered fixed prostheses supported by 4 or 6 dental implants in edentulous mandible with three-dimensional finite element method.

METHODS

The first design was 4 implants supported fixed prostheses with 6mm distal cantilever; the second design was 6 implants supported fixed prostheses with 6mm distal cantilever. Vertical force of 100 N was applied to the distal cantilever of fixed prostheses.

RESULTS

The bone stress was concentrated at the cortex of mandible. The maximum bone stress was at the cortex near the second implants from the point that the vertical force was applied. The maximum implant stress was at the terminal and medium implant-prostheses interface.

CONCLUSIONS

The bone around the terminal implant is easily to absorb and the terminal and medium implants are easily to fracture. The maximum stress of the implants and prostheses of two kinds of design are almost same(239Mpa). Two kinds of design can be applied in the clinic. 6 mm distal cantilevered fixed prostheses supported by 6 implants have the less bone stress than 4 mm distal cantilevered fixed prostheses in edentulous mandible.