Effect of surface treatment and manufacturing process on the shear bond strength of veneering composite resin to polyetherketoneketone (PEKK) and polyetheretherketone (PEEK)

Abstract

Statement of problem: Polyaryletherketones (PAEKs) are high-performance polymer materials in which polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) are the most used. Although mechanical and shear bonding strength tests have been performed on the 2 materials, studies on the influence of processing on bonding are scarce.

Purpose: The purpose of this in vitro study was to determine the influence of the surface treatment and the manufacturing process on the shear bond strength of veneering composite resin to PEKK and PEEK.

Material and methods: Thirty pressed PEKK, 30 milled PEKK, and 30 milled PEEK specimens were distributed in 6 groups (n=13) as per the manufacturing process and treatment surface. The specimens were either treated with airborne-particle abrasion with 110-μm aluminum oxide, or no surface treatment was applied. Moreover, the PEKK specimens were grouped regarding their manufacturing process, as either milled or heat-pressed. The specimens were all bonded by using a methyl methacrylate-based adhesive (visio.link), and composite resin (Gradia Revolution 2) was bonded to the specimens. An Instron universal machine was used to calculate the shear bond strength between the PEEK or PEKK and the composite resin. Two specimens from each group had their topography modification assessed with a scanning electron microscope. Statistical analysis was performed by using a 3-way ANOVA for multiple comparisons (α=0.05) RESULTS: The groups that were surface treated with 110-μm aluminum oxide (Al₂O₃) before bonding showed significantly higher shear bond strength (P=.001) than the other groups. However, no statistically significant difference was observed among the groups, regardless of the manufacturing process (milled or heat-pressed) (P=.607).

Conclusions: PEEK and PEKK surfaces treated with 110-μm aluminum oxide airborne-particle abrasion displayed better shear bond strength to composite resin. The manufacturing process (milled or heat-pressed) did not significantly affect the bond strength of PEKK when subjected to the same bonding process.