The fit of cast and premachined implant abutments

Statement of problem. There is insufficient information regarding the adaptation of abutments to implants. Purpose. This study assessed the adaptation of premachined, cast, and laboratory modified premachined abutments to implants at two sites: abutment/implant interface and screw to screw seat. Material and methods. Six combinations of abutments and implants were studied: CeraOne abutments joined to Nobel Biocare implants; STR (Implant Innovations Inc.) abutments joined to 31 implants; Cast UCLA (31) abutments subjected to porcelain firing cycles and joined to 31 implants; Cast UCLA abutments subjected to porcelain firing cycles and joined to Nobel Biocare implants; UCLA. premachined abutments cast with gold palladium alloy and subjected to porcelain firing cycles (later joined to 31 implants); and UCLA premachined abutments joined to 31 implants. Each group contained five assemblies. Results. The adaptation of abutments to implants was closer and the amounts of contact larger for assemblies with premachined and laboratory modified premachined abutments than for those with cast abutments. Conclusion. The finishing of custom-made abutments requires further refinement.