Reproducibility and accuracy of measuring unerupted teeth using limited cone beam X-ray CT

Objective: The purpose of this investigation was to determine the reproducibility among observers and accuracy of the measurement of the tooth crown width of unerupted teeth using limited area cone beam X-ray CT. Methods: 3DX multi-image micro-CT (3DX, Morita Co., Kyoto, Japan) images of impacted supernumerary teeth in the median maxillary region taken prior to extraction were used for the samples. The width of the tooth on the 3DX image was measured five times by five individual observers. Significant differences in values among the observers in the measurement were determined by one-way analysis of variance for examining reproducibility. The measurement results of the ten samples on 3DX images were compared with the laboratory measurements using a three-dimensional co-ordinate measuring apparatus, using the Wilcoxon signed-rank sum test. Results: There was no significant difference among the observers in the measurement (P > 0.05). The measurement results shown on 3DX images were significantly larger than those of the laboratory measurements (P < 0.05). The mean difference was +0.088 mm. Conclusions: 3DX has high reproducibility for measuring the tooth crown width of unerupted teeth. While 3DX measurement values were larger than the laboratory measurements, the difference is clinically insignificant.