Effect of the screw-retained abutment material on the fatigue behavior of lithium disilicate restorations.

The aim of the study was to evaluate the effect of the screw-retained abutment material (zirconia (Yz), lithium disilicate (Ld), Polymer-infiltrated ceramic network (Picn), and Polietheretherketone (Peek)) on the fatigue behavior and stress distribution of lithium disilicate restorative material. Ld discs (Ø= 10 mm; thickness = 1 mm) were obtained and allocated into four groups according to the abutment material factor: Yz, Ld, Picn, and Peek (Ø= 10mm; thickness 3 mm). A screw access hole was made at the center of each abutment and filled with resin composite (thickness = 2 mm). The materials were adhesively bonded and tested under monotonic mechanical load (n= 3) and cyclic fatigue (n= 15; initial load: 200 N for 10,000 cycles; step size: 100 N/10,000 cycles; frequency: 20 Hz) until failure. Finite element and Scanning Electron Microscopy (SEM) analyses were also performed. The obtained data were analyzed by 1-Way ANOVA for monotonic (α=0.05) and Kaplan Meier and log-rank post-hoc for fatigue data tests. All groups presented a decrease in the fatigue failure load (FFL) when compared to the monotonic test. The abutment material affected the lithium disilicate restoration performance (p=.048; F= 4.134), since zirconia showed the highest FFL (p<.05), followed by Picn and Ld, which were similar to each other (p>.05). The lowest values of FFL were found for Peek (p<.05). The screw-retained abutment material influences the fatigue behavior of lithium disilicate restorations, being zirconia the most indicated material to enhance mechanical performance.