Changes in prosthetic screw stability because of misfit of implant-supported prostheses.

Purpose: The effect of two levels of prosthesis misfit on prosthetic screw stability was evaluated.

Materials And Methods: Two levels of vertical discrepancies--100 and 175 microns--were introduced between an implant-supported complete denture and the terminal abutment. An implant-supported complete denture without vertical discrepancy served as a control. Cyclic load was delivered vertically on the cantilever portion of the prosthesis next to the terminal abutment for 48 hours for each trial. A total of seven sets of new screws were tested for each level of fit.

Results: The results revealed significant prosthetic screw instability at both the 100- and 175-micron levels of discrepancy.

Conclusion: Vertical discrepancies of 100 and 175 microns introduced between an implant-supported fixed complete denture and the terminal abutment resulted in significant prosthetic screw instability.