Enhancing bonding and durability of polyaryletherketone (PAEK) restorations with nonthermal plasma activation and monomer-based priming

Statement of problem: While valued for their durability in dental prosthetics, polyaryletherketone (PAEK) materials, known for their chemical inertness and low surface energy, pose significant challenges in achieving durable adhesion to resin cements, a critical factor for the long-term success of dental restorations. Purpose: This study evaluates the novel application of a methyl methacrylate-urethane dimethacrylate (MMA-UDMA) bonding primer following handheld nonthermal plasma (HNP) treatment to enhance the bonding performance and aging durability of PAEK materials with varying microfiller compositions, addressing the persistent challenge of achieving long-term adhesion in dental restorations. Material and methods: Three PAEK types, ceramic-filled polyetheretherketone (PEEK), titanium dioxide-filled polyetherketoneketone (PEKK), and PEEK with disk shape (Ø10×2.5-mm) were airborne-particle abraded using 110-µm Al₂O₃ at 0.2 MPa. Specimens were then evenly allocated into 2 main groups: one group received surface bonding primer (SBP) application alone, while the other group underwent HNP treatment followed by primer application (PLP). Surface wettability and shear bond strength (SBS) were assessed before and after artificial aging protocols, which included thermocycling and highly accelerated stress testing. Failure modes were analyzed microscopically to identify adhesive, mixed, or cohesive failures. Statistical analysis was performed using 3-way ANOVA and the Tukey HSD test (α=.05). Results: PLP-treated groups showed significantly improved wettability and increased SBS across all materials compared with SBP (P<.05), with the PLP-treated PEKK achieving the highest SBS at 16.35 MPa. After artificial aging, PLP-treated specimens revealed minimal reduction in SBS, with PEKK maintaining superior performance and the smallest decrease observed compared with others (P<.05). Failure mode analysis indicated a higher incidence of mixed failures for PLP-treated specimens, suggesting enhanced bond durability. Statistical analysis confirmed that differences across material types and treatments were significant (P<.05), highlighting the effectiveness of the HNP and primer application in improving long-term adhesion. Conclusions: HNP treatment followed by MMA-UDMA primer application significantly improved the bonding performance and durability of PAEK materials used in dental prostheses. The current findings indicated that this method addressed the persistent challenge of achieving long-term adhesion, particularly in materials with high ketone content.