Comparison of the Fracture Strength of Endocrowns Manufactured from Hybrid Blocks under Axial and Lateral Forces

Objectives: The present study aimed to compare the fracture strength of endocrowns manufactured from hybrid blocks under the axial and lateral forces.
Methods: One hundred permanent lower first molar teeth were root canal treated and assigned to 5 groups according to the material type. Endocrown restorations were produced from IPS e.max CAD (IPS Group) (Ivoclar Vivadent, Schaan, Lichenstein), Vita Enamic (VE Group) (Vita Zahnfabrik, Bad Sackingen, Germany), GC Cerasmart (GC Group) (GC America, Alsip, IL, USA), Shofu (SH Group) (Shofu Dental Mfg.CO., Kyoto, Japan) and Brilliant Crios (BC Group) (Coltene Whaledent, Altstatten, Switzerland) using CAD/CAD technique. Restorations were luted using self-adhesive resin cement. Following cementation all specimens were subjected to thermal cycle process. After, artificial aging the specimens were mounted on Universal test device and divided into 2 subgroups. Half of the specimens were subjected to axial and the other half was subjected to lateral forces. Loading was applied at a crosshead speed of 1 mm/min until fracture occurred. Fracture types were evaluated under stereomicroscope. Data were statistically analyzed.
Results: Statistically significant differences were observed among groups regarding the fracture strength values under axial and lateral forces (P < 0.05). The highest fracture strength values under axial and lateral forces were detected in BC Group and IPS Group, respectively. The lowest fracture strength values under axial and lateral forces were detected in SH Group and GC Group, respectively. No statistically significant differences were detected among groups regarding the distribution of failure types under axial and lateral forces (P > 0.05). The fracture types under axial and lateral forces were mostly Type I and restorable fractures.
Conclusions: The content of hybrid blocks was effective on the fracture strength of materials.