Fatigue limits of different PEEK materials for dental implants.

The increasing use of PEEK (poly-ether-ether-ketone) as a substitute for metal implant components has led to the suggestion that it could also be used as an alternative to titanium in the field of dental implants. A major requirement for dental implant materials is their resistance to cyclic loading due to mastication. A special fatigue test was designed to evaluate the elastic behavior and long-term form stability of cylindrically shaped PEEK specimens of 4, 5 and 6mm in diameter, using 11 different PEEK materials of various grades: unfilled, filled with titanium dioxide or barium sulfate powder, reinforced with short carbon fibers or short glass fibers, and reinforced with continuous carbon fibers. The samples were exposed to cyclic loads of up to 2000N. The elastic limits ranged between 46.57±6.44MPa for short carbon fiber reinforced specimens of 6mm diameter and 107.62±8.23MPa for samples of a different short carbon fiber reinforced PEEK compound of 4mm diameter. The elastic limits of the two PEEK grades containing continuous carbon fibers could not be observed because they exceeded the limits of the test specification. The elastic moduli ranged between 2.06±0.18GPa for barium sulfate powder filled PEEK-specimens of 6 mm diameter and 57.53±14.3GPa for continuous carbon fibers reinforced PEEK-specimens of 4 mm diameter. In terms of the elastic limit all the PEEK materials in consideration were able to resist the pressure caused by maximum masticatory forces.