Effect of different surface pre-treatments and luting materials on shear bond strength to PEEK

Objectives. To assess the bonding potential of a universal composite resin cement and an adhesive/composite system to differently pre-treated PEEK surfaces. Methods. One hundred and fifty PEEK disks were embedded in epoxy resin, polished (P4000 grit) and treated as follows (n = 30/group): (A) no treatment, (B) acid etching with sulfuric acid (98%) for 1 min, (C) sandblasting for 10 s with 50 mu m alumina, (D) sandblasting for 10 s with 110 mu m alumina and (E) silica coating using the Rocatec system (3M ESPE). Polished and sandblasted (50 mu m alumina) cp titanium (grade 4) served as a control. Acrylic hollow cylinder were either luted with a universal composite resin cement (RelyX Unicem) or an unfilled resin (Heliobond) and a hybrid composite (Tetric) to the specimens. Bond strength was measured in a shear test and failure modes were assessed. Statistic analysis was performed with one-way ANOVA followed by a post hoc Scheffe test and unpaired t-tests. Results. With the universal composite resin cement, no bond could be established on any PEEK surfaces, except specimens etched with sulfuric acid (19.0 +/- 3.4MPa). Shear bond strength to titanium was significantly lower (8.7 +/- 2.8 MPa, p < 0.05). Applying the adhesive/composite system, shear bond strength values on pre-treated PEEK ranged from 11.5 +/- 3.2 MPa (silica coating) to 18.2 +/- 5.4 MPa (acid etched) with no statistically significant differences (p > 0.05). No bond was obtained on the polished surface. Significance. Bonding to PEEK is possible when using a bonding system. No adherence can be achieved with the tested universal composite resin cement except on an etched surface. The results strongly encourage further research in PEEK application in dentistry. (C) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.