Screw loading and gap formation in implantsupported fixed restorations: Procera implant bridge vs. conventionally cast screw-retained restorations

Objectives: It was the purpose of this finite element analysis to compare the implant-restoration connection created by Procera Implant Bridge (PIB) and conventional screw-retained prostheses with respect to screw loading and gap formation. Method and Materials: Finite element models representing a conventional screw-retained restoration and a PIB were set up. A horizontal load of 200N was applied on the restorations while resulting gap formation and screw loading was recorded. Results: Increasing the preload of the retaining screws led to a decrease in gap formation. Smaller gaps were observed in the conventional restorations. Loading of the screws was of comparable magnitudes in both cases. Conclusion: The use of screw-retained implant-supported restorations representing butt-joint connections at the restorative interface may result in increased gap formation. Keywords: gap formation, implant-abutment interface, Procera Implant Bridge, screw joint stability