Surface treatments for polyetheretherketone (Peek): Effects on the bond strength to a resin cement and on the fatigue performance of a bonded glass-ceramic

Objective: To evaluate the effect of distinct surface treatments on Peek (polyetheretherketone) adhesion to the resin cement and the mechanical fatigue behavior of lithium disilicate adhesively bonded to it.Materials and methods: Peek slices embedded in plastic rings with self-curing acrylic resin were randomized into 4 groups for adhesion testing, considering the following surface treatment factors: Ctrl (just cleaned with 78 % isopropyl alcohol); Grinding (4219F diamond bur -46 mu m grain size); Air abrasion (45 mu m aluminum oxide for 10 s); Sulfuric acid (acid etching for 30 s). All slices received a layer of adhesive agent; resin composite cylinder specimens (& Oslash; = 3 mm; h = 3 mm) were produced and bonded onto the Peek slices using a dual resin cement for the shear bond strength tests (n = 20) through the wire-loop technique. Next, disc-shaped specimens of Peek (& Oslash; = 10 mm; thickness: 2 mm) and lithium disilicate (LD) (& Oslash; = 10 mm; thickness: 1 mm) were produced for the fatigue tests (n = 20) and paired. The LD was treated (5 % hydrofluoric acid for 20 s + silane agent) and adhesively bonded (with dual resin cement) onto Peek (treated with the previously mentioned surface treat-ments). The fatigue tests were performed with a step-stress approach (20 Hz; 10,000 cycles/step; initial load: 100 N; step-size: 50 N). Roughness, contact angle, topography and fractographic analysis were performed. The adhesive data was analyzed by one-way ANOVA and Tukey post-hoc tests, while the fatigue data were subjected to survival analysis (Kaplan Meier and Mantel-cox post hoc tests).Results: Only the air abrasion surface treatment was able to improve the bond strength between Peek and resin cement (p < 0.05); the Grinding and Sulfuric acid groups were similar to the Ctrl. All surface treatments promoted similar fatigue performance. Conclusion: Air abrasion promoted increased bond strength between Peek and resin cement, having no detrimental effect on fatigue behavior. Overall, the mechanical behavior under fatigue of a lithium disilicate glass-ceramic was not influenced by the Peek substrate surface treatments.