Absence of Passive Fit of the Prosthesis
A passive fit of the prosthesis reduces long term stresses in the superstructure, implant components and the bone adjacent to the implants. The absence of passive fit may manifested clinically as:
- Pain and discomfort to the patient.
- Loosening or fracture of the implant components.
In literature a passive fit should exist at the 10 micron level and is imperative to obtain optimal load distribution. The reasons for non passive framework include inaccurate impressions, improper laboratory techniques in terms of spacer application techniques, matching casting shrinkage of metal not matched with the mould expansion. The use of soldered connectors in long span fixed restorations is an excellent way to compensate the inaccuracies inherent to the laboratory procedures.