To demonstrate the need for proper restoration of root-filled teeth.
Tooth fracture can be a sequel to root-canal treatment. It is associated with the removal of excessive amounts of the tooth substance during the instrumentation phase, the use of unnecessary force during obturation, or inadequate planning of the design of the eventual coronal restoration to include appropriate cuspal protection. Rarely, a fracture may be present in a tooth before treatment commences, but remains undetected. A case describing incomplete vertical tooth fracture of a root-filled mandibular first molar is presented.