Effect of combining different surface treatments on the surface characteristics of polyetheretherketone-based core materials and shear bond strength to a veneering composite resin

Statement of problem. High-performance polyetheretherketone (PEEK) has been used in dentistry because of its excellent physical and chemical properties. However, its lack of translucency requires the use of a veneering composite resin for esthetic applications. Data on bonding a veneering composite resin to PEEK are still scarce. Purpose. The purpose of this in vitro study was to assess the effect of using and combining different surface treatments on the surface roughness and wettability of PEEK core materials and the shear bond strength (SBS) to a veneering composite resin. Material and methods. Sixty square PEEK specimens were divided according to surface treatments into 6 groups: group N, no surface treatment; group A, airborne-particle abrasion; group L, ER:YAG laser treatment; group LA, laser treatment and airborne-particle abrasion; group P, plasma treatment; and group PA, plasma treatment and airborne-particle abrasion. Surface roughness (Ra) and wettability (contact angle theta) were measured followed by evaluation of the surface topography. After veneering, the SBS was measured. A 1-way analysis of variance (ANOVA) was used to assess all interactions with multiple pairwise comparisons (alpha=.05). Results. The highest mean Ra values were obtained for the combination treatment groups (LA 2.94 +/- 0.1 and PA 2.7 +/- 0.1 mu m) (P<.001). While the laser (13 +/- 0.1 mu m) and plasma treatment (1.4 +/- 0.1 mu m) groups had the lowest Ra values, LA and PA had the highest wetting of PEEK surfaces (LA 6.9 +/- 0.7 and PA 4.9 +/- 0.2 degrees) (P<.001). The highest mean SBS values were demonstrated on PEEK surfaces with combination treatments (LA 22 +/- 1.3 and PA 21.2 +/- 0.8 MPa) (P<.001). Conclusions. Combining airborne-particle abrasion with laser or plasma treatments increased the surface roughness and wettability of PEEK surfaces favorably compared with applying each of the 3 treatments individually. The combinations enhanced the bond strength of PEEK to the veneering composite resin.