Effect of the interface and alloy composition on the in vitro marginal fit and mechanical properties of implant-supported frameworks

A precise or so-called passive fit between the implant supported prosthesis (ISP) and implant abutments is regarded essential to protect the load bearing capacity of the screw joints and implants from high stresses. The efficacy of section-and-solder and Preci-Disc methods to correct ISPs inaccuracies following their castings were evaluated as well as the load bearing capacity of the modified frameworks.; Standardised ISP frameworks were fabricated using either Preci-Disc system (palladium-gold (PdAu); cobalt-chromium (CoCr) or silver-palladium-gold (Ag-Pd-Au) alloys) or cast-over method (PdAu alloy). The relative distortion of the frameworks to the prosthetic analogue was assessed before and after modification of the frameworks according to the specific modification method, using coordinate measuring machine. The load under which the modified frameworks failed was measured using universal testing apparatus.; None of the measured frameworks provided a completely passive fit. However, their modification, by either section-and-solder or Preci-Disc system, reduced the three-dimensional distortion relative to the prosthetic analogue. The Preci-Disc system was the more efficacious system in improving framework fit to the master model and the resultant distortion values were lower than the components manufacturing tolerance. Regardless of the alloy used in this study, this system consistently produced passively fitted frameworks, without apparent reduction in their mechanical properties. Moreover, the latter system can be used intraorally and can reduce the cumulative error from all fabrication stages.