A Study on the Fracture Strength of Implant-Supported Restorations Using Milled Ceramic Abutments and All-Ceramic Crowns

Purpose: The purpose of this study was to compare five different abutment-crown combinations for single implant-supported restorations regarding their capabilities to withstand loads. Materials and Methods: Fifty implants were placed into resin blocks, and the restorations were connected to the implants. The five tested restorations were: (1) metal-ceramic crowns cemented to titanium abutments, (2) In-Ceram crowns cemented to titanium abutments, (3) Celay feldspathic crowns cemented to titanium abutments, (4) In- Ceram crowns cemented to milled ceramic abutments, and (5) Celay feldspathic crowns cemented to milled ceramic abutments. The specimens were loaded at 0- and 45-degree angles to the long axis, and the load values at the moment of failure were recorded using a universal testing machine. Results: The fracture strengths under vertical loading were greater than those under oblique loading. The fracture strengths of metal-ceramic crowns cemented to the titanium abutments were higher than those of all-ceramic crowns cemented on the milled ceramic abutments, regardless of loading direction. There were no differences in the fracture strengths of the ceramic crowns between the two different abutment types under oblique loading. Conclusion: All-ceramic crowns on the milled ceramic abutments were weaker than the metal-ceramic crowns on the titanium abutments under oblique loading.