Effect Of Different Surface Pre-treatments On The Bond Strength Of PEEK Bioactive Composite

Objective:To evaluate the effect of different surface treatments on the bond strength betweenpolyetheretherketone (PEEK) or PEEK bioactive composite and a universal composite resincement (RelyXTMUnicem). The surfaces were observed by scanning electron microscopyafter the different pretreatments. The de-bonding surface was examined under astereomicroscope to evaluate the failure modes of the samples. However, as this was thebasic study, the main goal was to assess the overall feasibility of establishing bonding toPEEK. This study is to provide a theoretical basis for PEEK that becomes alternative repairmaterials for future clinical development.Materials and Methods:PEEK and PEEK composites were prepared for this study. PEEK was recorded ascontrol group. PEEK composites were recorded as experimental group. The specimens ofcontrol group or experimental group were randomly divided into six test groups (n=10)according to the following surface treatments:(A) no treatment,(B)98%sulfuric acid,(C)9.5%hydrofluoric acid,(D) silanization (E) argon plasma treatment, and (F) sandblast with50μm Al2O3particles. Then, the different pretreatments surfaces were observed by scanningelectron microscopy to perform micro-morphologic examination. A universal compositeresin cement (RelyXTMUnicem) was bonded onto the specimens. After24h at37°Cdistilled water storage, bond strength was measured in a shear test, and failure modes wereassessed by stereomicroscopy. Through comparing the values of shear bond strength ofspecimens with literature, we analyzed and discussed the effect of six different surfacetreatments on the bond mechanism of polyetheretherketone (PEEK) or PEEK bioactivecomposite.Result:SEM analysis showed the different surface morphology after different surface treatmentand grooves or cracks appeared on the PEEK surface. For the control group, Etching with98%sulfuric acid treatment can significantly enforce the shear bond strength of incomparison to the group of sandblasting or argon plasma treatment (p <0.01). No significantdifference (p>0.05) was observed between sandblasting and argon plasma treatment. For the experimental group, shear bond strength values were statistically significant among thegroups. These values were ordered by magnitude as follows:98%sulfuric acid treatment>argon plasma treatment> sandblasting (p <0.01). No adhesion was established on thegroups of no treatment, hydrofluoric acid and silanization treatment in the control andexperimental groups. Using the same pretreatment, there is no statistical difference (p>0.05)between the control and experimental group, excepting for the sandblasting group (p <0.01).The main failure mode was adhesive in all groups by stereomicroscopy.Conclusion:1. Etching with98%sulfuric acid and argon plasma treatment can significantly enforcethe bond strength of RelyXTMUnicem to PEEK or PEEK composites.2. Sandblasting can enforce the bond strength of RelyXTMUnicem to PEEK or PEEKcomposite. But, the former was higher than the latter with sandblasting.3. The use of9.5%hydrofluoric acid and silanization are not viable. Thus, effectivesurface treatments of PEEK composites and favorable adhesives need to be explored infuture experimental studies.