Mechanical complications of dental implants.

Adverse occlusal forces can result in mechanical complications of implant components. While unacceptably high incidences of mechanical failures have been reported for the two-stage external hex screw-type implant systems, the standard-diameter ITI solid-screw implant does not seem to be vulnerable to these problems. The 8 degrees Morse taper has eliminated abutment screw loosening and fracture. The incidence of prosthetic screw loosening has been minimized by the 45 degrees bevel on the implant shoulder and by the 1.5 mm vertical abutment walls. The design of the standard-diameter solid-screw ITI implant and the material used in its fabrication (cold worked type IV cp titanium) have eliminated fixture fracture. However, because there have been some reported instances of fractures involving reduced-diameter and hollow implants, these designs should be used with caution.