To evaluate the long-term clinical and radiographic effects of maxillary incisor root resorption in cases of ectopic canines treated during the late 1970s and 1980s in Jönköping, Sweden. The material comprised 55 incisors in 38 subjects. The posttreatment follow-up time was 13 to 28 years. All subjects underwent intraoral radiography, 33 were referred for computed tomography or cone beam computed tomography, and 24 also underwent clinical examination. The severity of incisor root resorption was correlated with clinical characteristics. Radiographs of the resorptive lesions were documented in detail and compared with intraoral radiographs taken immediately posttreatment. Four incisors in three subjects had been lost, in part because of root resorption. Of the 36 incisors with root resorption, the lesions were unchanged in 26 teeth, improved in three teeth, and exacerbated in seven. In one case the resorption had progressed to pulpal exposure, necessitating endodontic treatment. For most of the incisors, the periodontal ligament was more clearly defined and the lamina dura showed improved trabeculation. The clinical characteristics of the incisors with resorption were not significantly different from those of sound incisors. In this long-term follow-up, most cases of incisor root resorption induced by ectopic maxillary canines did not progress and teeth with root resorption showed no clinically relevant symptoms. The prognosis for long-term survival of teeth with resorbed roots is good, but in cases where extraction is indicated, lateral incisors with severe root resorption should be extracted in favor of healthy premolars.