Impact of cone beam CT on diagnosis of external cervical resorption: the severity of resorption assessed in periapical radiographs and cone beam CT. A prospective clinical study

Objectives: To compare the severity of external cervical resorption (ECR) observed in periapical (PA) images and cone beam CT (CBCT) using the Heithersay classification system and pulp involvement; and to assess inter- and intra observer reproducibility for three observers. Methods: CBCT examination was performed in 245 teeth (in 190 patients, mean age 40 years, range 12-82) with ECR diagnosed in PA images. Three observers scored the severity of ECR using the Heithersay classification system (severity class 1-4) and pulp involvement (yes/no) in both PA images and CBCT. Percentage concordance and ic-statistics described observer variation in PA images and CBCT for both inter- and intra observer reproducibility. Results: For all three observers, the ECR score was the same in the two modalities in more than half of cases (average 59%; obs1: 54%, obs2: 63%, obs3: 61%). However, in 38% (obs1: 44%, obs2: 33%, obs3: 36%) of the cases, the observers scored more severe ECR in CBCT than in PA images (p < 0.001). The ECR score changed to a less severe score in CBCT only in 3% (obs1: 1%, obs2: 4%, obs3: 4%). For pulp involvement, 14% (obs1: 7%, obs2: 20%, obs3: 15%) of the cases changed from "no" in PA images to "yes" in CBCT. In general, lc values were higher for CBCT than for PA images for both the Heithersay classification score and pulp involvement. Conclusions: ECR was generally scored as more severe in CBCT than PA images using the Heithersay classification and also more cases had pulp involvement in CBCT.