Comparative Evaluation of Fracture Resistance of Structurally Compromised Canals Restored with Different Dowel Methods

PURPOSE: The objective of this in vitro study was to evaluate and compare the fracture resistance and fracture mode of endodontically treated teeth with wide root canals restored with various dowel methods. MATERIALS AND METHODS: Fifty human uniradicular mandibular premolar teeth were decoronated and endodontically treated. The canals were widened with diamond points. The specimens were divided into five groups on the basis of type of dowel method used: conventional custom-made cast metal dowel; single glass fiber-reinforced resin dowel; glass fiber-reinforced resin dowel with accessory fiber dowels; relined glass fiber-reinforced resin dowel; and dowels formed with the help of polyethylene fiber ribbon-reinforced resin composite. Specimens were restored with indirect composite crowns, and 150,000 cycles of cyclic loading were applied. The specimens were loaded to test the fracture resistance and fracture mode (repairable and nonrepairable). RESULTS: The cast metal dowel groups had the highest fracture resistance but showed nonrepairable fracture in 90% of specimens. CONCLUSIONS: Cast metal dowels had the highest fracture resistance but led to nonrepairable fracture while restoring the wide root canals under cyclic loading. Specimens restored with fiber dowels, accessory dowels, relined dowels, and ribbon-reinforced resin provided adequate fracture resistance with increased incidence of repairable fractures.