Marginal discrepancy of screw-retained and cemented metal-ceramic crowns on implant abutments

Th is in vitro study quantified the marginal discrepancy of the implant-to- prosthetic-crown interface on nonsubmerged dental implants restored with ei ther a cemented or a screw-retained approach. Metal-ceramic crowns were fab ricated for 20 ITI 4.1 x 10 mm solid-screw titanium implants. Ten implants received octa abutments and screw-retained crowns fabricated on premachined gold cylinders. The remaining 10 implants were restored with 5.5-mm solid abutments and metal-ceramic crowns cemented alternately with a glass-ionome r or a zinc phosphate luting agent. Inspection of the implant-crown interfa ce was conducted using light microscopy under x50 magnification at selected stages in the process of crown fabrication. Statistical analysis revealed a significant difference (P < .001) in the mean marginal fit between screw- retained (8.5 +/- 5.7 mu m) and luted implant-supported crowns. This differ ence was observed both before (54.4 +/- 18.1 mu m) and after cementation wi th glass-ionomer (57.4 +/- 20.2 mu m) or zinc phosphate (67.4 +/- 15.9 mu m ).