Abutment connection structural changes in dual-retained and screw-retained metal-ceramic implant-supported restorations: an in vitro study, part I

Abstract

Abstract Background This study sought to compare the rotational freedom and structural changes of abutment connections in dual-retained and screw-retained metal-ceramic implant restorations at different fabrication stages and following thermomechanical loading. Methods Twenty metal-ceramic restorations were equally divided into two groups. Group 1 (G1) consisted of dual-retained restorations on prefabricated titanium abutments, while Group 2 (G2) comprised screw-retained restorations on UCLA chromium-cobalt overcast abutments. Specimens underwent 500 cycles of thermocycling and 500,000 cycles of mechanical loading. Changes in connection dimensions and rotational freedom were compared within and between the groups before- and post-loading. Statistical analyses were conducted using a generalized linear model (GLM). The significance level was set at α = 0.05. Results Initially, no significant differences in connection dimensions were observed between the groups (P >.05). After loading, G2 exhibited significantly smaller hexagon side lengths and diagonal measurements, along with increased hexagonal angle deformation and concentricity (P .05). Conclusions Dual-retained restorations outperformed screw-retained ones with minimal connection alteration and higher rotational stability.

Keywords

• Dental implants
• Dental prosthesis
• Implant supported dental prosthesis
• Prosthesis fitting
• Single tooth dental implant