Investigation of the effect of fiber laser applications on the bonding between polyetheretherketone (PEEK) and resin cement material

The aim of this study; To investigate the effect of ultrafast fiber laser on the surface roughness of PEEK and its bond with resin cement. In this study, 114 samples (8x8x3 mm) were obtained from PEEK blocks. The samples were randomly divided into 10 separate groups: Group 1 (Ko); untreated (control), Group 2 (Ku); Sandblasted with 50 μm Al₂O₃, Group 3 (KuMP); Sandblasting with 50 μm Al₂O₃ and metal primer application, Group 4 (KuSP); Sandblasting with 50 μm Al₂O₃ and ceramic primer application, Group 5 (Uf); ultrafast fiber laser (5W) application, Group 6 (UfMP); ultrafast fiber laser and metal primer application, Group 7 (UfSP); ultrafast fiber laser and ceramic primer application, Group 8 (Er); Er, Cr; YsGG laser (3W) application was made, Group 9 (ErMP); Er, Cr; YsGG laser and metal primer application, Group 10 (ErSP); Er, Cr; YsGG laser and ceramic primer application. The surface roughness of the samples was measured with a profilometer. One sample from each group was examined with a scanning electron microscope (SEM). Metal (Alloy Primer) or ceramic (Clearfil Ceramic Primer Plus) primers were applied to the samples. Adhesive agent (Visio.link) and resin cement (Panavia SA Cement Plus) were applied to all samples. All samples were thermally aged up to 5000 cycles. Fracture values were calculated by applying shear test. One sample from each group was analyzed by TEM and energy distribution spectrometry (EDS) analysis. Data were analyzed by one-way Anova and Tukey's post hoc test. In this study, the highest surface roughness value was determined in the Er group compared to other surface treatments. According to the results, the highest bond strength value was found in the Ku group, while the lowest values were found in the Er, ErMP and ErSP groups, respectively. In the SEM images of the samples roughened with Er,Cr; YsGG laser, it is seen that the adhesive and resin cement cannot flow into the craterlike areas formed on the PEEK surfaces. Uf group showed significantly higher connectivity values than the control group (p<0.05). Metal and ceramic primer application did not increase the bond value after mechanical surface treatments. As a result, fiber laser applications can be an alternative to sandblasting to increase the bond between PEEK and resin cement. Sufficient mechanical locking could not be achieved due to the inability of the adhesive and resin cement to flow into the pits formed by the Er,Cr; YsGG laser etching.