Methods: Rectangular plates of commercially pure (CP) titanium grade 2 (20.0 mm length, 12.0 mm width，1.0 mm thickness) were prepared in this study. The plate surfaces were polished using an abrasive paper #800. The masking tape with the hole of 4.8mm in diameter was attached to the titanium surface so that adherent area was determined. After the specimens were set up at distance of 1 cm from ultraviolet rays lamp, UV was irradiated under the following conditions: output 15 mW/cm2, wave length λ=254 nm, irradiation time 30 and 60 min, using a UV radiation device (UV/Ozone Cleaner, BioForce Nanosciences, USA). Metal adhesive primer (alloy primer, Kuraray) was immediately applied to bonding surface and auto-polymerized polymethyl methacrylate (PMMA) resin (Provista, Sun Medical) was poured and polymerized using brush-on technique. As a control, the bonding specimen without UV irradiation was also prepared. Tensile test was performed using autography (Instron 5565) at a crosshead speed of 1.0 mm/min. Bonding strengths (n=5) were analyzed using a one-way ANOVA and Tukey’s multiple comparison test (α=0.05).
Results: UV irradiation more than 30 min showed the higher bonding strengths than the control (p<0.05). However, there was no significant difference of irradiation time between 30 and 60 min (p>0.05). This was due to the improvement of the wettability of the titanium surface would by UV irradiation.
Conclusions: The UV irradiation of 30 minutes or more could improve the adhesive property of the PMMA resin to the titanium surface.