Effect of the contamination and cleaning methods on the tensile bond strength of the polyetheretherketone restorative material cemented with dual-cure resin cement

Abstract

BACKGROUND: These days, computer-aided design/computer-aided manufacturing (CAD/CAM) resinbased materials are being used daily in clinical practice for restorations in prosthetic dentistry. In comparison with ceramic materials, they are characterized by better stress distribution and decreased abrasion of the enamel of the opposing teeth. Consequently, they have been applied as alternative materials to ceramics in various dental restorations. OBJECTIVES: The contamination of the indirect restorative material, which occurs at the clinical and dental laboratory stages, might deteriorate the bonding strength. The ideal surface treatment of the novel polyetheretherketone (PEEK) material for decontamination is yet unknown. The present study was conducted to evaluate the tensile bond strength (TBS) between PEEK and dual-cure self-adhesive resin cement, and determine the effect of contaminants, like temporary cement, artificial saliva and a fit checker, as well as the cleaning methods, like ultrasonic cleaning, phosphoric acid etching and universal cleaning paste (Ivoclean), on the bond. MATERIAL AND METHODS: Eighty PEEK disks were milled, having the final dimensions of 12 mm × 4 mm. The specimens were air-abraded with 50-micrometer aluminum oxide particles at a pressure of 2.8 bar for 15 s at a fixed distance of 10 mm, and then divided into 4 groups according to the contaminant used: temporary cement; artificial saliva; a fit checker; and a control group with no contamination. Furthermore, the first 3 groups were subsequently subdivided into 3 subgroups each according to the cleaning method applied: ultrasonic cleaning; phosphoric acid etching; and universal cleaning paste Ivoclean. The bonding of the specimens was done using dual-cure self-adhesive resin cement. The TBS of the different groups and subgroups was then measured at a crosshead speed of 2 mm/min in a universal testing machine (UTM), using a special test configuration. RESULTS: There was a significant interaction between both tested variables (the contamination and cleaning methods) (p < 0.001). The samples contaminated with artificial saliva showed a significantly higher TBS value than the samples subjected to other contaminants (p = 0.005). For the samples contaminated with temporary cement and a fit checker, there were significant differences between the different cleaning methods, with ultrasonic cleaning providing the highest TBS values, followed by phosphoric acid etching, and finally Ivoclean (p < 0.001). CONCLUSIONS: Under the conditions of the present study, temporary cement and a fit checker adversely affected the TBS of PEEK, and ultrasonic cleaning was most effective for decontamination.