▎ 摘　　要

This study aimed to synthesize and characterize graphene oxide (GO) nanoparticles and study the spectral, microbiological, and mechanical analysis of GO in two types of resin adhesives bonded to two-piece zirconia abutments. GO was synthesized and the nanoparticles were characterized using a scanning electron microscope (SEM). Four experimental groups were formed based on weight percentage (0.25 wt% and 0.5 wt%) of GO added in conventional chemically activated resin cement and the other two groups with dual-cure cement. Two nonmodified adhesive groups served as the control groups. Sixty sets of zirconia abutments cemented to screwed titanium bases of implants analogs were divided into 6 groups. Spectral analysis and degree of conversion (DC) were performed using micro-Raman and Fourier-transformed infrared spectroscopy (FTIR). Bacterial viability was studied using the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazoli-umbromide (MTT) assay over the implant. On SEM analysis, GO (thickness of 1-2 nm thick flakes) nanoparticles were uniformly dispersed throughout the adhesive matrix. Raman and FTIR analysis confirmed the presence of D and G bands. Implant specimens treated with 0.5 wt% GO-modified dual-cure adhesive demonstrated the lowest mean score of DC (38.75 +/- 6.37). After 1 day and 30 days of incubation with dental adhesives, 0.5 wt% GO-modified chemically activated adhesive specimens showed high antibacterial activity; only 23% and 30% of Streptococcus mutans were able to survive after treating with 0.5 wt% GO-modified chemically activated adhesive, respectively. In conclusion, incorporation of 0.5 wt% of GO in both chemically activated and dual-cure adhesive produced superior antimicrobial and physical characteristics for bonding two-piece zirconia abutments to screwed titanium bases.