Comparative evaluation of fracture resistance of different CAD/CAM fabricated endocrowns - in vitro study

Background: The aim of the study was to compare the fracture resistance of recent CAD/CAM restorative materials that recently used for the fabrication of endocrown restorations.
Methods: 30 endocrowns were fabricated on 3D printed resin dies and divided into three groups (n=10) according to the endocrown material. Group A: lithium disilicate Endocrowns (IPS E-max CAD), Group B: resin infiltrated ceramic (Vita Enamic), and group C: Nanohybrid composite (Brilliant Crios). All endocrowns were subjected to axial compressive strength using a universal testing machine, until failure, and the values were recorded. Fracture resistance values in Newton (N) and failure modes of the restorations were evaluated using an optical microscope. All collected data were tabulated and statistically analyzed. Numerical data were described as mean and standard deviation and compared using a Two-way ANOVA test. The level of significance was set at α P≤0.05.
Results: fracture resistance values of all tested materials were within the acceptable clinical range for all groups. The lithium disilicates endocrowns showed statistically significantly higher mean fracture resistance values than the polymer infiltrated and nanohybrid composite endocrowns. While the nanohybrid composite Endocrowns showed better mode of fracture than that of lithium disilicate.
Conclusions: Within the limitations of this study, Emax endocrowns showed better fracture resistance followed by Vita enamic endocrowns. While brilliant crios Endocrowns revealed a better mode of failure despite it’s low fracture resistance values.