Comparison of fracture strength of endocrowns and glass fiber post-retained conventional crowns

The aim of this in vitro study was to compare the fracture strength of full ceramic crowns using two techniques-indirect conventional crowns retained by glass fiber posts, and endocrowns with an "anchorage" in the pulp chamber-and analyze the failure mode. For this purpose, 20 healthy mandibular molars were divided into two groups (n=10): GroupGC contained teeth with indirect conventional crowns, filling cores, and glass fiber posts; Group GE contained teeth with restorations of the endocrown type. Teeth were endodontically treated and prepared for ceramic restorations fabricated by the injection technique(IPS e.max Press, Ivoclar-Vivadent), forming the GC and GE groups. Specimens were mount-ed in a universal test machine (EMIC) and were submitted to an oblique compression load, at an angle of 135 degrees to the long axis of the tooth, until failure. Statistical evaluation performed by the Mann-Whitney nonparametric test showed significant differences between the two groups (p=0.002), with Group GE shown to be more resistant to compressive forces than Group GC. The pre-dominant failure pattern in both groups was fracture of the tooth on the side of force application and/or consequent displacement of the restoration on the opposite side.