Effect of aging on fracture resistance and torque loss of restorations supported by zirconia and polyetheretherketone abutments: An in vitro study.

STATEMENT OF PROBLEM: New materials have been developed for digital processing, including implant abutments, but studies on their mechanical properties are lacking. PURPOSE: The purpose of this in vitro study was to compare the effect of aging on the fracture resistance, failure mode, and torque loss of restorations made of zirconia and ceramic-reinforced polyetheretherketone (PEEK) abutments with titanium bases. MATERIAL AND METHODS: Titanium-based PEEK and zirconia abutments were milled and veneered with composite resin or feldspathic porcelain in the form of maxillary first premolars (n=10). All the specimens were subjected to an aging process and were assessed after every 250 000 cycles under a stereomicroscope, and torque loss was recorded with an electronic torque meter. Fracture resistance was measured under static load (crosshead speed of 1 mm/min), and failure modes and final torque were determined. A t test was conducted for statistical analyses (alpha=.05). RESULTS: The fracture resistance of the zirconia restorations was significantly greater than the PEEK-based restorations (P=.001). Torque losses were not significantly different after aging (P=.18); however, significant difference was recorded after the fracture test (P=.007). The effect of fracture load was significantly greater for the zirconia group (P<.001). Unlike with the zirconia group, the failure mode in the PEEK-based restorations was mainly adhesive and favorable (9 of 10 specimens). CONCLUSIONS: Ceramic-reinforced PEEK abutments had acceptable resistance to fracture, a favorable failure mode, and successfully sustained the aging process.