Effects of various laser applications on surface roughness and bond strength to veneering composites of polyether ether ketone (PEEK) and polyether ketone ketone (PEKK) materials.

The aim of this study was to investigate the bond strength between PEEK/PEKK and composite resins after various laser treatments and to compare the effectiveness of lasers on these polymers. 130 disc-shaped PEEK and PEKK blocks were obtained (10 mm diameter-4 mm height). One sample from each group (10 in total) was selected for scanning electron microscopy (SEM) analysis. The samples were randomly divided into 5 different surface treatment groups for each material (PEEK and PEKK): Er: YAG laser, Nd: YAG laser, diode laser, femtosecond laser and control (no surface treatment) (n = 12). Baseline and post-treatment surface roughness measurements were performed using a profilometer. The composite resin was bonded and SBS was measured. Comparisons among the groups were conducted via Kruskal-Wallis, one-way ANOVA; Tukey and Dunn tests were used as a post hoc test (p ≤ 0.05). All lasers significantly increased the roughness values of the PEEK and PEKK samples. In terms of shear bond strength; the Er: YAG and femtosecond laser groups had the highest values and the Nd: YAG, diode and control groups had the lowest values of the PEEK samples (p ≤ 0.05). The control group had the highest bond strength values and the femtosecond group had the lowest values for PEKK samples (p ≤ 0.05). All laser treatments increased the surface roughness of the PEEK and PEKK. Lasers increased the bond strength of PEEK to the veneering composite resin and decreased the bond strength values of PEKK. This shows that lasers behave differently in PEEK and PEKK materials.