Promotion of resin bonding to dental zirconia ceramic using plasma deposition of tetramethylsilane and benzene

The aim of this study was to investigate the effects of plasma‐enhanced deposition of an organosilane and benzene on resin bonding to a dental zirconia ceramic. A total of 70 zirconia specimens, which were polished before sintering, were randomly divided into five groups according to surface treatments before applying a dental adhesive (each group, n = 14): group 1, no previous treatment (control); group 2, plasma deposition with tetramethylsilane ( TMS ); group 3, plasma deposition with benzene; group 4, sequential plasma deposition with TMS and benzene; and group 5, a zirconia primer (Z‐Prime Plus). A dental adhesive (Scotchbond Multi‐Purpose adhesive) was applied to the surface‐treated zirconia, and resin composite rods were built in to enable shear bond‐strength testing. The sequential deposition of TMS and benzene showed the highest bond strength [22.7 ± 3.7 MP a (mean ± SD )], approximately twice that of Z‐Prime Plus (10.3 ± 3.2 MP a). The plasma deposition with either TMS or benzene also significantly improved bond‐strength values compared with the negative‐control group, and their effects were not statistically different from that of Z‐Prime Plus. Following plasma deposition with TMS , the introduction of silicon–oxygen–zirconium (Si–O–Zr) bonds on the zirconia surface was confirmed via X‐ray photoelectron spectroscopy ( XPS ) analysis. Transmission electron microscopy and energy dispersive X‐ray spectroscopy showed that a silica‐like layer and a polymerizable carbon‐rich layer were formed through sequential deposition with TMS and benzene.