In Vitro and In Vivo Evaluation of Yttria-Niobia-Stabilized Zirconia Sandblasted Surface at Bone-Implant Interface with 3-Dimensional Visualization via Advanced Hard Tissue Clearing

Abstract

Titanium is widely acknowledged as the "gold standard" for dental implants because of its superior biocompatibility and osseointegration capabilities. However, it is limited by the possibility of metal allergies, aesthetic concerns such as gray discoloration visible through the thin gingiva, and the risk of corrosion. To overcome these limitations, metal-free implant materials, particularly yttria-niobia-stabilized tetragonal zirconia polycrystals ((Y,Nb)-TZP), have attracted increasing attention. Zirconia has been noted for its advantages, including promising mechanical properties, biocompatibility, aesthetics, and reduced bacterial adhesion. Despite these findings, comparative studies of sandblasted, large-grit, acid-etched (SLA) titanium and (Y,Nb)-TZP are limited. This study aimed to compare the in vitro osteogenic potential and in vivo osseointegration of sandblasted (Y,Nb)-TZP implants with those of conventional SLA titanium implants using 3-dimensional evaluation. (Y,Nb)-TZP implants demonstrated comparable in vitro and in vivo results to SLA titanium, despite significantly lower surface roughness. Early cell attachment and spreading were observed on (Y,Nb)-TZP, whereas alkaline phosphatase activity and late-stage osteogenic gene expression increased over time in both groups without intergroup differences. In in vivo experiments, no significant between-group differences were observed in bone-to-implant contact, bone area, and dynamic bone remodeling indices. Three-dimensional-based analysis revealed similar overall bone remodeling volumes but distinct spatial distributions of newly formed bone around the implant threads, providing additional insights into the subcortical peri-implant bone area. In conclusion, sandblasted (Y,Nb)-TZP implants exhibited osteogenic potential and osseointegration comparable to those of SLA titanium implants, supporting the potential clinical applicability of (Y,Nb)-TZP as an alternative implant material.