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Keywords:

  • Cross-pin;
  • gasket;
  • implant supported restoration;
  • leakage

Abstract

Background:  Advantages of cross-pin retained implant supported restorations (ISRs) include predictable retrieval and predictable retention. Unlike direct to fixture (DTF) or cement retained restorations, the prosthetic design of a cross-pinned restoration retains gaps at the interfaces between the crown, abutment and cross-pin screw. These spaces permit leakage into the suprastructure and gasket placement has been recommended to prevent this leakage.

Methods:  Five different gaskets were assessed for their ability to prevent leakage into a cross-pinned ISR. The gaskets tested were: cement admixture on the cross-pin screw; cement admixture on the inner surface of the coping and the cross-pin screw; cement admixture on the inner surface of the coping only; cement admixture placed 1 mm from the margin of the coping and a filler placed in the abutment chimney.

Results:  Only gaskets which sealed both the cross-pin screw interface and the abutment-crown interface prevented leakage. A filler placed in the abutment chimney prevented leakage into this space but did not prevent fluid accumulating between the coping and abutment. Conservative placement of cement at the margin of the coping failed to prevent leakage.

Conclusions:  Cement gaskets may effectively prevent leakage into a cross-pinned ISR. However, the use of a cement as a gasket has to be weighed against the issue of predictable retrieval, cement extrusion and incomplete seating.