Plasma Flow Effects on Bonding Between Composite and Fiber Post

The perfect bonding interface between the fiber reinforced composite post and composite resin is required in order to achieve the monobloc characteristic.  At present, it is difficult to obtain such a perfect interface between two different materials. Objectives: The objective of this study was to evaluate the effect of two plasma flows on tensile shear bond strength using pull out test. Methods: Two fiber reinforced composite posts, DT light post (DT) (RTD, St. Egreve, France) and FRC postec (FRCP) (Ivoclar Vivadent, Schaan, Liechtenstein) were used as substrate in surface preparation. DT represented epoxy and FRCP represented aromatic, aliphatic dimethacrylate resin matrix. Each brand of post (n=6) was ionized in 2x10^-2 Torr vacuum chamber with Argon plasma flow (AR) or Oxygen plasma flow (O) using radiofrequency generator at 13.56 MHz, 50 W for 10 minutes. No treatment on post (n=6) served as control. After treating post with plasma flow, the parallel coronal end of 2 mm in height was bonded with Multicore Flow (Ivoclar Vivadent, Schaan, Liechtenstein) without any bonding or coupling agent application. The pull out tensile test was performed using a universal testing machine (Lloyd, LR10K, UK) with a crosshead speed of 1 mm/min.  The tensile shear bond strength (MPa) was calculated by dividing the maximum force with bonding area.  The data were analyzed using 2-ways ANOVA and Scheffe multiple comparison at p<0.05. Results: The means ± standard deviations for control, AR and O of DT were 11.75±3.3, 11.90±2.1 and 10.12±2.3 MPa respectively. For control, AR and O of FRCP were 7.91±1.9, 15.97±2.2 and 10.99±2.5 MPa respectively. Two-way ANOVA revealed significant differences on treatment factor and the interaction. Scheffe revealed significant differences between argon treatment and the others. Conclusion: Argon plasma flow enhances tensile shear bond strength between resin composite and fiber reinforced composite post.