The investigation of the effect of various surface treatments on surface roughness, phase transformation and bond stength of polietheretherketone

Aim: The aim of this study was to see how different surface treatments for polyetheretherketone (PEEK) affected surface roughness, composite resin bond strength, and phase transformation analyses. Material and Methods: A total of 140 specimens of 5x5x2 mm dimensions were prepared from PEEK blocks. After standardizing the specimens surfaces with 1200 grit silicon carbid paper, they are divided into seven groups (n=20) to apply different surface operations: untreated samples, sulfuric acid application, piranha solution application, sander with Al2O3, tribochemical sander, and ER-YAG laser and plasma application. The surface topography assessment of the specimens was performed using a profilometer device. Scanning Electron Microscopy (SEM) was used to obtain surface imagines of the specimens, and an Energy Distribution Spectrometer was used to analyze elemental change (EDS). On extra specimens produced from each group, phase change analysis was performed using an X-Ray Diffractometer device. Following the application of the adhesive system to the samples' joint surfaces, composite resin was applied and polymerized using a 3 mm customized roller mold. The specimens were aged for 5000 cycles at temperatures ranging from 5 to 55 °C after being stored in water at 37 °C for 24 hours. Shear bond strength test was performed by the Univercal test machine. Obtained data were evaluated with one-way ANOVA test and Tukey multiple comparative test. The results were evaluated at the p˂0.05 significance level. Results: According to test data obtained, the highest surface roughness value was obtained in the sandblasting group with Al2O3 (3.09 μm) and the highest bond strength value was obtained in the sulfuric acid group (13.28 MPa) (p˂0.05). As a result of the correlation analysis, no statistically significant relationship was found between the surface roughness and bond strength values (p>0.05). Different peak points were observed in the Al2O3 sandblasting and laser groups compared to the control group. Conclusions: The surface roughness of all the surface treatment applied in the study and was found to increase the bond strength. All of the surface treatments used in the study increased surface roughness and bond strength, according to the results. Surface chemical changes have been shown to be just as important as physical changes in bond strength. Keywords: PEEK, Surface treatment, Surface roughness, Bond strength, Phase transformation