Polyether ether ketone in protocol bars: Mechanical behavior of three designs

Abstract

Aim: This study evaluated the compressive strength (CS) of protocol bars on polyether ether ketone (PEEK) implants compared to metallic bars (NiCr). Materials and Methods: Thirty PEEK bars and thirty metallic bars (control) were produced using three different cross-sectional designs (n = 10): rectangular cross-section solid bar (R), T-type (T), and inverted T-type (T inv). All bars were 30 mm long. The bars were screwed to Cone Morse implants of 3.75 mm × 11.0 mm and submitted to compression strength test in a universal testing machine (0.5 mm/min), with the load applied to the bar cantilever. After the test, we measured the counter torque on the screws. Results: Compression strength (N) and counter torque (N/cm) data were analyzed with two criteria: ANOVA and Tukey (α = 0.05). PEEK bars showed mean compression strength significantly lower than NiCr bars, for all designs (P < 0.001), with R bars showing the best results and T inv, the worst results. PEEK bars showed smaller counter torque values than NiCr bars for R or T designs (P = 0.002). Conclusion: For PEEK bars, T inv design resulted in the smaller compression strength. PEEK solid bars, with rectangular cross-section, showed larger resistance to compression in comparison to the other designs. However, PEEK bars showed lower compression strength than that verified for metallic bars.