In the study of Naumova et al., volume and vertical wear of PICN crowns, compared to other materials such as a nanoceramic resin and a lithium silicate reinforced ceramic after CS, were tested [11]. They used the same settings of CS as in the present study, but the crowns were luted to extracted molars instead of implants and extracted molars as antagonists were used as well. Concerning volume and vertical wear after CS, PICN crowns showed the lowest cusp abrasion, much lower than in our study. Due to the use of abutment teeth instead of dental implants, the results cannot be compared to ours.

Mörmann et al. compared the surface wear of different dental ceramics including Vita Enamic [12] after the same type of mechanical loading as in the present study. The results showed similar wear to other CAD/CAM materials as well as to human enamel. Since enamel of extracted molars was used as indenters in this study, it cannot be compared directly to our procedure. Nevertheless, a remarkable difference could be found in the results of the SEM images. Mörmann et al. described the surface of abrasion as similar to the polished surface [12], which cannot be found in our specimen.

According to Lauvahutanon et al., PICN crowns show minor wear compared to direct restorations made of composite [13].

Until now, there have been numerous publications on VE [3,4,5,6, 10,11,12,13,14,15,16,17,18,19,20,21,22,23,24] but only one study has investigated the combination with zirconia implants [5] where fracture strength of VE and feldspathic ceramic on zirconia implants was compared using different luting agents. Fracture strength was tested by applying an axial force to the specimen until fracture. The results showed higher fracture strength of VE. The samples were placed in distilled water for 24 h after cementing, so no dynamic loading occurred. Due to the different study designs—no pull-off forces, no dynamic loading, and no wear tests—it cannot be compared to ours.