3-DIMENSIONAL FINITE-ELEMENT ANALYSIS OF STRESS-DISTRIBUTION AROUND SINGLE TOOTH IMPLANTS AS A FUNCTION OF BONY SUPPORT, PROSTHESIS TYPE, AND LOADING DURING FUNCTION

The elastic limit of bone surrounding implants may be surpassed and th us produce microfractures in bone. The purpose of this study was to us e computer simulations to examine clinical situations with IMZ implant s in edentulous mandibles and to identify loading conditions that coul d lead to bone microfractures. Three-dimensional finite element analys is models were used to examine effects of: (1) types of edentulous man dibles, (2) veneering materials, (3) the absence of cortical bone, (4) different intramobile elements, (5) loading directions, and (6) loadi ng levels. Stress distribution patterns were compared and interfacial stresses were monitored specifically at four heights along the bone-im plant interface. Stresses were concentrated toward cortical bone (0.8 to 15.0 MPa). There were no differences between types of veneering mat erials and the absence of cortical bone increased interfacial stresses . The use of a titanium intramobile element decreased stresses. Minor stress increases were associated with smaller mandibles. Oblique loads increased stresses 15 times, and 200 N loads increased stresses 10 ti mes. Conditions for bone microfracturing were associated with oblique loads, high occlusal. stress magnitudes, and the absence of cortical b one.