Fracture behavior of endodontically treated premolar teeth restored with different lithium silicate-based endocrown restorations

Background This study aimed to assess the fracture behavior of endodontically treated maxillary first premolars restored with different lithium silicate-based endocrown restorations. Methods Thirty intact human maxillary first premolars were root canal treated. They were divided into three groups ( n = 10) based on the CAD/CAM lithium silicate-based material used for endocrown fabrication: Group LD: Lithium disilicate-based ceramic (IPS e.max CAD), Group ZLS: Zirconia-reinforced lithium silicate-based ceramic (Celtra Duo), and Group ALD: Advanced lithium disilicate-based ceramic (Cerec Tessera). After adhesive cementation, all specimens underwent a thermomechanical aging process. Surviving specimens underwent fracture resistance testing, followed by analysis with stereomicroscopy and Scanning Electron Microscopy (SEM). Data were statistically analyzed at P-value ≤ 0.05. Results The mean failure load value was significantly higher for Group ALD (1853.89 ± 178.40 N) compared to Group LD (1425.57 ± 156.31 N) and Group ZLS (1364.12 ± 196.34 N). A statistically significant difference in failure mode was detected among tested groups, with more favorable fracture patterns observed within Groups ZLS and ALD. Conclusions All studied lithium silicate-based endocrown restorations expressed fracture load values that significantly surpassed the maximum human masticatory force reported for maxillary premolar region supporting their clinical use. Cerec Tessera endocrowns exhibited the best biomechanical behavior among tested restorative materials. Clinical trial number Not applicable.