Development and Evaluation of a Novel Self-Etch Dental Adhesive Incorporating Graphene Oxide-Zirconia (GO-ZrO(2)) and Hydroxyapatite-Zinc (HA-Zn) for Enhanced Bond Strength, Biocompatibility, and Long-Term Stability.

The aim of this study was to develop an experimental self-etch dental adhesive (SE) by synthesizing graphene oxide-functionalized zirconia (GO-ZrO(2)) and hydroxyapatite-functionalized zinc (HA-Zn) as inorganic powders together with bis-GMA ((0-2)) (bisphenol A-glycidyl methacrylate) oligomers as main components of the organic matrix. The adhesive was compared to the current gold standard adhesive Clearfill SE Bond 2 (CSE) using cytotoxicity assays, shear bond strength (SBS) tests, and resin-dentin interface analyses. Cytotoxicity assays with human gingival fibroblasts (HGF-1) revealed reduced cell viability at early time points but indicated favourable biocompatibility and potential cell proliferation at later stages. SBS values for the experimental adhesive were comparable to CSE after 24 h of storage while aging did not significantly affect its bond strength. However, SBS exhibited more consistent resin tag formation and higher Weibull modulus values post-aging. A scanning electron microscopy (SEM) analysis highlighted differences in resin tag formation, suggesting the experimental adhesive relies more on chemical bonding than micromechanical interaction. The experimental adhesive demonstrated promising potential clinical properties and bond durability due to the integration of GO-ZrO(2) and HA-Zn fillers into the adhesive.