Adherence of polyetheretherketone (PEEK) to different veneering materials and evaluation of the mechanical properties
Hafiz, Walid Khalid
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OBJECTIVES: To test and compare the effects of thermocycling, different bilayer material combinations, and different core/veneer material combinations on shear bond strength, flexural strength, and failure load of different dental restorative materials. METHODS: In this in-vitro study, 369 specimens were prepared from four materials; PEEK (Juvora), Vita Enamic, MarkII, and InCoris (Sirona). 144 specimens were divided into 12 groups and sectioned into plates (frameworks) and rods (veneers) for the shear bond strength test. The final dimension of each plate was about 18mm in length, 2mm thick, and 12mm in width. While the rods were core drilled to have a final diameter of 3.48mm. All plates and rods underwent surface treatment before bonding with adhesive resin (3M RelyX Ultimate), half of the specimens were thermal aged with 5,000 cycles before a shear bond strength test was performed on all specimens. 225 specimens were sectioned into bars for bilayer flexural strength test and load to failure analysis. The final dimension of the bars was 18mm in length, 2mm thickness, and 4mm width, bars were assigned into groups of tension materials and compression materials to be bonded together as a bilayer bar structure. Half of the bilayer bars underwent thermal aging. All bilayer and monolayer bars were tested for flexural strength, load to failures values were also analyzed as well as the mode of failures. RESULTS: The results of this study show that Enamic groups (EN/MKII) showed the highest shear bond strength (SBS) followed by Zirconia groups (Zr/En, Zr/MKII). PEEK groups show the lowest SBS values among the tested groups. Thermal aging did not affect SBS specimens except for Zr/En group where it decreases the SBS values. There was a significant difference in bilayer flexural strength and failure loads of Zirconia groups (Zr/En, Zr/MKII) were higher than other groups. PEEK groups (PEEK/EN, PEEK/MKII, PEEK/Zr) showed the lowest FS bilayer and load to failure values. CONCLUSION: SBS to PEEK was lower as compared to the other tested groups. Materials in tension and the adhesive interface layer significantly impact the bilayer flexural strength and failure load values.