The influence of the restorative material on the mechanical behavior of screw-retained hybrid-abutment-crowns

Abstract

BackgroundThe use of polymers in implant dentistry is gaining popularity, as they might have several advantages due to their shock absorption capacity. PurposeThe aim of this study was to evaluate the performance and fracture strength of three resilient shock-absorbing polymer-based materials as well as the widely used ceramics as one-piece screw-retained implant-supported hybrid-abutment-crowns. Materials and methodsForty custom-made CAD/CAM one-piece screw-retained restorations were milled out of 5 different monolithic materials (n = 8); Z: 3Y-TZP zirconia, L: lithium disilicate, P: ceramic-reinforced polyetheretherketone (PEEK), C: nano-hybrid composite resin and E: polymer-infiltrated ceramic-network. Specimens were subjected to dynamic loading for 1,200,000 cycles with integrated thermal cycling. The surviving specimens were subjected to quasi-static loading until failure. Shapiro-Wilk test was used to test for normality, and Levene test was conducted to test the homogeneity of variance. One-way ANOVA test followed by Tukey's post-hoc test were used to detect statistically significant differences between groups. ResultsAll specimens withstood 1,200,000 cycles of thermo-dynamic loading with no signs of cracks or screw loosening. The median values of fracture strength varied from a minimum of 670 N for group E to a maximum of 2645 N for group Z. ConclusionsFracture strength of screw-retained hybrid-abutment-crowns is influenced by the material used. Zirconia showed superior results. However, its fracture strength was comparable to that of PEEK, which additionally enjoys a shock absorbing property.