Digital Dental Tech LabSeoul National Univeristy School of Dentistry

Objectives: To evaluate the effect of surface treatment on the pull-out force of implant restorations supported by Ti-bases and milled from fully sintered niobium oxide-containing yttria-stabilized tetragonal zirconia polycrystals ([Y, Nb]-TZP), and to compare their fracture load with that of lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) restorations.

Methods: To evaluate pull-out force, 40 (Y, Nb)-TZP hybrid abutment-crown specimens were divided into four groups based on the surface treatment applied (n = 10): no surface treatment (FSZ-N group), airborne-particle abrasion (APA) (FSZ-A group), a 10-methacryloyloxydecyl dihydrogen phosphate (MDP) primer (FSZ-M group), and both APA and a 10-MDP primer (FSZ-AM group). After cementation and thermocycling, the pull-out forces and failure modes were examined by pull-out testing. To evaluate fracture load, 30 hybrid abutment-crown specimens were milled from (Y, Nb)-TZP (fully sintered zirconia; FSZ group), LD (LD group), and PICN (PICN group) blocks (n = 10). Following cementation and thermocycling, fracture loads and failure modes were recorded.

Results: The FSZ-M and FSZ-AM groups demonstrated significantly higher pull-out forces than the FSZ-N group. The FSZ-A group showed the lowest pull-out force. The LD group had a higher fracture load than the PICN group. The fracture load of the FSZ group showed no significant difference compared with the LD or PICN group.

Conclusions: Applying a 10-MDP-containing primer enhanced the pull-out force of hybrid abutment-crowns milled from fully sintered (Y, Nb)-TZP, with or without APA. Implant restorations fabricated from this material and supported by Ti-base abutments exhibited a fracture load comparable to that of LD and PICN restorations.

Clinical significance: For implant restorations milled from fully sintered zirconia and supported by Ti-base abutments, applying a 10-MDP-containing primer is a key step for improving retention. Furthermore, their fracture load, which is comparable to other restorations milled from established materials, supports their potential for clinical use on Ti-base abutments.