Effect of a crown ferrule on the fracture strength of endodontically treated canines restored with fiber posts and metal-ceramic or all-ceramic crowns.

The aim of this study was to comparatively evaluate the fracture strength of endodontically treated canines restored with glass-fiber posts (GFPs) and either metal-ceramic (MC) or all-ceramic (AC) crowns in the presence or absence of 2 mm of ferrule height. Fifty human maxillary canines were endodontically treated and randomly divided into five groups of 10 specimens each. The first group remained intact (control), while the remainder were restored with GFPs and composite cores with either MC or AC crowns. Each of the AC and MC groups was equally divided between teeth with or without ferrule. Teeth were embedded in acrylic resin and loaded at a 135-degree angle to their long axis until fracture. Fracture strength was not significantly different between ferrule and no ferrule groups (P = .571), but was significantly larger for the MC groups compared with the control and AC groups (P = .009 and P = .024, respectively). A significant effect of the type of restoration was found as teeth restored with MC crowns presented significantly higher fracture strength, independently of ferrule.