Three groups of zirconia abutments (n = 5) consisting of different connection designs or manufacturers were investigated (All-Zr, ASC-Zr, and AM-Zr groups). All-electric dynamic test instruments were used to place static loading on a specimen with a crosshead speed set at 1 mm/min. A Kruskal–Wallis test and a post hoc Mann–Whitney U test were used for statistical evaluation. The mean fracture resistance was 252.37 ± 82.79 N for the All-Zr group, 384.62 ± 45.24 N for ASC-Zr group, and 361.83 ± 90.31 N for the AM-Zr group. The difference of fracture resistance between the three groups was marginally significant (Kruskal–Wallis test, p = 0.054), with the ASC zirconia abutment tending to have higher fracture resistance than the full zirconia abutment. The modes of failure among the three types of abutments are different. The All-Zr group showed an oblique fracture line starting from the buccal aspect at the region of the implant platform. While the ASC-Zr and AM-Zr groups showed a relatively horizontal fracture line with a greater distance from the implant platform. The titanium inserts cannot significantly improve the fracture resistance of the zirconia abutment. However, they may alter the modes of failure, allowing buccal fracture surfaces of the zirconia abutments to be placed away from the implant platform, thereby protecting the implant–abutment connection.

The use of aftermarket computer-aided design/computer-assisted manufacturing (CAD/CAM) prosthesis components in dental implants has become popular. This study aimed to (1) compare the accuracy of aftermarket CAD/CAM screws with that of original equipment manufacturer (OEM) abutment screws and (2) examine the biomechanical effects of different abutment screws used with zirconia abutment in an implant fixture by using three-dimensional finite element analysis (FEA). Significantly different measurements were obtained for the aftermarket CAD/CAM and OEM screws. The FEA results indicated that under the same loading condition, the maximum stress of the aftermarket CAD/CAM screws was 15.9% higher than that of the OEM screws. Moreover, the maximum stress position occurred in a wide section of the OEM screws but in the narrowest section of the aftermarket screws. The stress of the OEM zirconia abutment was 14.9% higher when using the aftermarket screws than when using the OEM screws. The effect of the manufacturing differences between aftermarket and OEM screws on the clinical effect of aftermarket screws is unpredictable. Therefore, aftermarket screws should be cautiously used clinically.

The purpose of this in vitro study is to compare the maximum load capacity and modes of failure under static loading in three types of titanium abutments (n = 3) with different processes or manufacturers. The Pre-Ti group consists of prefabricated titanium abutments from original equipment manufacturers (OEM), the CAD-Ti group consists of OEM titanium abutments fabricated with computer-assisted design/manufacturing (CAD/CAM) technique, and the AM-Ti group is CAD/CAM titanium abutment made by aftermarket manufacturers. A full zirconia crown was fabricated and cemented to each abutment. An all-electric dynamic test instrument was used to place loading on the zirconia crown with a crosshead speed set at 1 mm/min. The mean maximum load capacity of both OEM titanium abutments was significantly higher than the aftermarket titanium abutments. All these three types of implant–abutment complexes exhibited similar modes of failure, which included deformation of the abutment and implant, fracture of the abutment and retentive screw.