Teeth restored with intracoronal restorations that provide no protection of the cusps from occlusal loading may fracture completely or partially. An incomplete dentinal fracture of a vital posterior tooth may cause pain. This condition is commonly known as the "cracked tooth syndrome". Location of the dentinal crack is difficult and must be guided by a precise history, thermal pulp testing and inspection of the dentinal walls within the suspect tooth. The number, extent and direction of the fracture lines may be ascertained readily by using transillumination and magnification. This allows the clinician to distinguish between oblique and vertical cracks. Treatment of oblique incomplete fracture relies on desensitisation of the hypersensitive dentine followed by splinting of the tooth fragments. Treatment of vertical incomplete fracture requires pulpectomy and immediate splinting of the crown. Two case reports are presented.