The term ‘cracked tooth’ has been used to describe many types of fractures in teeth. One type of dental fracture is the Crown-originating fracture (COF). A COF typically originates in the tooth crown and is not related to previous root canal treatment. A COF is often extremely difficult to diagnose because symptoms vary widely and may mimic other pathologic conditions. This Quality Resource Guide (QRG) provides an evidence-based discussion of the COF, including characteristics, symptoms, diagnosis (using radiographic information, clinical/tactile findings, pulp testing, percussion and periodontal probing), treatment options and prognosis. A section also discusses appropriate methods of communicating with the patient through the sometimes very difficult processes of determining a diagnosis and selecting a treatment option. The QRG is an important reference for the clinician assessing a patient presenting with pain that is suspected of being from a tooth. It also provides background information for the dental office team to answer patients’ questions regarding a potential COF and the options they face regarding therapy.