The fracture strength of endocrowns manufactured from different hybrid blocks under axial and lateral forces.

Abstract

This in vitro study was conducted to compare the fracture strength of endocrowns manufactured from different hybrid blocks under axial and lateral forces. Following root-canal treatment, 100 permanent mandibular first molars were randomly distributed among 5 groups according to restoration material. Endocrown restorations were produced from IPS e.max CAD (IPS), Vita Enamic (VE), GC Cerasmart (GC), Shofu (SH), and Brilliant Crios (BC) using CAD/CAM technology. Specimens were cemented, subjected to artificial aging, and further divided into 2 subgroups (n = 10) per group for fracture testing. Each specimen was placed on a universal testing machine and subjected to axial or lateral forces applied at a crosshead speed of 1 mm/min. Fracture data were analyzed using one-way ANOVA, Tukey, Tamhane T2, and Weibull tests. Statistically significant differences in fracture-strength (FS) values under axial and lateral forces were observed among the groups (P < 0.05). Group BC had the highest FS value under axial forces, whereas group IPS had the highest FS value under lateral forces. According to Weibull analysis, VE exhibited the highest reliability under axial forces (7.62), whereas IPS exhibited the highest reliability under lateral forces (4.68). No statistically significant differences were detected in the distribution of failure types under either axial or lateral forces among the groups (P > 0.05). All of the hybrid blocks tested showed sufficient fracture strength for use as CAD/CAM-fabricated endocrowns. Hybrid blocks can be used as an alternative to lithium disilicate blocks in endocrown restorations.