Comparative in vitro assessment of zirconia, lithium disilicate, and advanced lithium disilicate ceramics for Ti-base restorations: Surface roughness, cytocompatibility, and quantitative fibroblast adhesion response.

Statement of problem: Peri-implant soft tissue integration and compatibility is critical for the long-term success of implant-supported restorations. Ceramics used with Ti-base abutments differ in their physicochemical properties and biological behavior. However, these differences remain incompletely understood.

Purpose: The purpose of this in vitro study was to compare the surface properties, cytocompatibility, and fibroblast adhesion response of zirconia (ZIR), lithium disilicate (LD), and advanced lithium disilicate (ALD) ceramics used for Ti-base restorations. All comparisons were performed using a standardized 2-dimensional (2D) in vitro culture model of human gingival fibroblasts.

Material and methods: Standardized ZIR (inCoris ZI), LD (IPS e.max CAD), and ALD (CEREC Tessera) (n=13) were fabricated according to manufacturer instructions. The study focused on 2D polished or glazed surface topography (Ra), cytotoxicity, integrin beta-4 (ITGB4) expression, and cytomorphology. Human gingival fibroblasts (hGFs) were cultured on each material, and cytotoxicity was assessed at 24, 48, and 72 hours using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. ITGB4 expression in hGFs, evaluated as an adhesion-related integrin marker, was quantified by enzyme-linked immunosorbent assay (ELISA) after 7 days. Cell morphology was examined by scanning electron microscopy (SEM).

Results: ZIR exhibited significantly lower surface roughness than LD and ALD (P<.001). All materials remained below the International Organization for Standardization (ISO) 10993-5 cytotoxicity threshold. ZIR demonstrated the lowest mean cytotoxicity and higher ITGB4 expression in hGFs compared with LD (adjusted P=.022), whereas ALD did not differ significantly from the other groups (LD, adjusted P=1.0; ZIR, adjusted P=.221). SEM was used solely for qualitative biological support.

Conclusions: All tested ceramics were biocompatible; however, ZIR provided the smoothest surface and a more favorable cellular response, as indicated by fibroblast adhesion. These findings suggested that polished ZIR may offer advantages for peri-implant soft tissue compatibility in the transmucosal region of Ti-base restorations.