Criteria for diagnosis of pulp necrosis in traumatized permanent incisors.

Records and radiographs of 108 patients (6-18 years) with 134 root canal treated incisors were examined. Subluxation was the most common type of injury, followed by intrusive, extrusive or lingual luxation, exarticulation and uncomplicated crown fracture. Negative response to electric stimulation was noted in 107 teeth from the first examination. In 23 teeth an initial positive response changed to negative within 3 weeks to 9 months, whereas persistent positive reactions were recorded in four teeth. The diagnosis of necrosis was based on the following observations: negative vitality and radiographic changes (76 teeth), negative vitality and discoloration (45 teeth), negative vitality only (nine teeth), positive vitality and radiographic changes (four teeth). External inflammatory root resorption confirmed the diagnosis of necrosis in all replanted teeth and in 13 of 16 intruded teeth. Discoloration and periapical lesions were the most important diagnostic factors following subluxation, extrusive and lingual luxation. Necrosis was disclosed within 4 months in 117 teeth (87%). Diagnoses based on negative vitality and discoloration were made within 6 days to 3 months in all but one case. All external root resorptions and 37 of the 49 periapical lesions were observed within 3 weeks to 4 months of the injury.