The aim of this clinical study was to assess 1032 endodontically treated roots in relation to: (i) the success rate of retreatment (612 roots)--only cases that had recall examinations of 6 months or longer were evaluated; (ii) the influence of various factors on the technical and clinical results of the retreatment; and (iii) the consequences of radiographic monitoring of 420 asymptomatic roots when the root filling was radiographically deficient (short, overextended and/or permeable root fillings). Technical assessment of the retreatment showed that the root was adequately sealed in 52.3% of cases, the root filling was improved in 33.8%, was identical with the initial treatment in 11.1% and was worse than the first treatment in 2.8% of the canals. Clinical assessment of the retreatment of symptomatic roots showed that 71.8% of the retreatments were judged successful, 18.9% showed some healing and 9.3% had failed. The initial size of the periapical lesion, the use of rubber dam, the root filling technique and the apical level of the root filling had a statistically significant influence on the result of the retreatment. Monitoring radiographically (median time span 6 years) led to maintenance of the status quo in 94.8% of cases, healing in 2.4% and failure in 2.8% of the canals. Retreatment is clearly indicated when periapical radiolucency, clinical signs and/or symptoms are present with relative success of up to 91%. When no or little radiographic evidence of periapical pathology was present, when clinical signs and symptoms were absent or when the root filling was radiographically deficient, radiographic monitoring led to complications in only a limited number of cases.
Keywords: clinical decision, endodontic retreatment, radiographic evaluation.