Construction of a Bioactive Layer Containing Akermanite on Zirconia Ceramics to Enhance Osseointegration and Soft Tissue Healing for Dental Implant

Zirconia ceramics exhibit numerous advantageous properties, including excellent biocompatibility, corrosion resistance, superior mechanical strength, and desirable aesthetic characteristics. However, as a typical bioinert material, zirconia demonstrates limited osseointegration and soft tissue healing capabilities, posing a significant clinical challenge for its application in dental implants. To address this limitation while preserving its mechanical integrity, we developed a novel porous surface layer composed of akermanite (Ca2MgSi2O7, AKT) on zirconia ceramics using a dip-coating process combined with negative pressure infiltration. This study systematically investigated the influence of AKT content on the morphology, phase composition, mechanical properties, and surface characteristics of the modified zirconia. Furthermore, we evaluated the material's bioactivity, cell viability, cellular adhesion and differentiation, and in vivo osteogenic potential. Following immersion in simulated body fluid (SBF), AKT-modified zirconia ceramics exhibited enhanced bioactivity, as evidenced by the formation of hydroxyapatite on their surfaces. Compared to unmodified zirconia, the AKT-modified samples demonstrated significantly improved hydrophilicity and apatite mineralization. In vitro cell culture experiments revealed that the modified ceramics promoted the adhesion, spreading, and osteogenic differentiation of mouse bone marrow stromal stem cells (mBMSCs), as well as the early adhesion, proliferation, and fibroblast differentiation of human gingival fibroblasts (HGFs). In vivo studies using a rabbit model confirmed the enhanced bone-implant integration capacity of AKT-modified specimens. Finite element analysis further revealed an optimized stress-strain distribution in peri-implant bone tissue due to surface modification. To our knowledge, this study provides the first comprehensive evidence that AKT-modified zirconia ceramics represent a promising dental implant material capable of simultaneously fulfilling the requirements for osseointegration and soft tissue compatibility.