Assessment of Micro-Gap in Hybrid Abutment-Crowns Fabricated with Different Materials

Abstract

Objective: The aim of this in vitro study is to evaluate the micro-gap changes in three dimensions after thermodynamic loading between hybrid abutment crowns made of different materials and implants with internal conical connection.
 Methods: A total of 10 morse cone connection implants (Straumann Bone Level Implant, Institut Straumann AG, Basel, Switzerland) were used. In this study, two study groups were formed using lithium disilicate glass-ceramic (LD) and polymethyl methacrylate (PMMA) in hybrid abutment-crown production (n=5). Hybrid abutment-crowns were fabricated by CAD/CAM system. Hybrid abutment crowns were designed and manufactured digitally. A 4-month of clinical cycle was applied to the samples in the chewing simulator. The micro-gap at the implant- abutment interface was visualized with micro-CT before and after thermodynamic loading. Micro-gap change was determined using these obtained images. For comparisons, independent t-test was used.
 Results: When comparing the micro-gap volumes before and after aging, no significant difference was observed between the LD and PMMA groups. The micro-gap increase after loading was 0.68 ±0.209 in the LD group and 0.45 ±0.373 in the PMMA group. Although the increase was higher in the LD group, there is no statistically significant difference between two groups.
 Conclusion: he micro-gap in the interface of implants and hybrid abutment crowns increased after aging. Hybrid abutment-crown material affected the micro-gap increase, but it was not statistically significant.