Influence of Machining, Polishing, and Glazing on Surface Properties and Biological Performance of Zirconia and Lithium Disilicate Dental Ceramics

Abstract

Surface treatments play a crucial role in modifying the surface properties and biological performance of dental ceramics. This study investigated the effects of surface conditions on the wettability, cytocompatibility, and bacterial resistance of 4 mol% Y2O3-stabilized tetragonal zirconia polycrystal (4Y-TZP) and two lithium disilicate (Li2Si2O5) glass ceramics (Amber (R) Mill (AM) and Amber (R) Mill Abut-Crown (AC)). Human gingival fibroblast (HGF-1) responses and biofilm formation on the machined, polished, and glazed samples were evaluated. The polished 4Y-TZP sample exhibited the highest water contact angle (WCA; 71.3 degrees), while that of the AC samples decreased as the sample was machined (58.4 degrees), polished (46.8 degrees), and glazed (14.0 degrees). The wettability, cytocompatibility, and bacterial resistance of the dental ceramics were significantly influenced by material type and surface condition. Among the surface-treated samples, the glazed specimens exhibited the lowest WCA and bulk density; thus, wettability is an important factor for cell proliferation and bacterial resistance. Among all samples, HGF-1 cells adhered well to the glazed ceramics and significantly proliferated over time. Particularly, the 4Y-TZP and AC glazed samples exhibited the lowest biomass and strong resistance to biofilm formation and bacterial adhesion. Thus, the glaze dramatically affected HGF-1 cell growth and antibiofilm formation.