Comparative Assessment of Post-Fatigue Resistance of Mandibular First Molars Restored With Polyether Ether Ketone and Lithium Disilicate Endocrowns.

Contemporary dentistry focuses on more conservative treatment options such as endocrown restorations and application of dental materials with higher resemblance to tooth structure. Polyether ether ketone (PEEK) polymer is a material used for the fabrication of endocrowns. This study aimed to compare the post-fatigue resistance (PFR) of mandibular first molars restored with PEEK and lithium disilicate (LS) endocrown restorations. This in vitro, experimental study was conducted on 20 human mandibular first molars with similar dimensions. The teeth were prepared for endocrown restoration and were assigned to two groups ( = 10) of PEEK and LS endocrowns. After fabrication by the computer-aided design and computer-aided manufacturing (CAD-CAM) technique, the restorations were cemented with resin cement. Next, the teeth underwent 15,000 thermal cycles followed by cyclic loading with 600,000 cycles of compressive force (100 N, 4 Hz) and were then subjected to compressive load application in a universal testing machine. The load causing endocrown failure was recorded as the PFR of the respective restoration. The failure mode was also inspected under a light microscope. Data were analyzed by the independent -test and also chi-square, Mann-Whitney, and Fisher's exact tests ( < 0.05). The teeth with PEEK endocrowns showed significantly higher PFR than those with LS endocrowns. Irreparable fractures were dominant in both groups. PEEK may serve as a suitable alternative to LS for the fabrication of endocrown restorations.