Abstract: Objective To evaluate the accuracy of cone-beam computed tomography (CBCT) and digital periapical radiographs (DPRs) for teeth length measurements by different doctors. Methods 46 CBCT images and 82 premolars were collected from the patients who were go?ing to undergo orthodontic treatment and would require premolar extractions. The teeth length measurements made by digital caliper was considered as the gold standard. The teeth length was measured by CBCT software on axial planes (APs), sagittal planes (SPs) and coronal planes (CPs) by two doctors respectively. Then the extracted teeth were matched the corresponding location of a dry skull. Standardized bisecting angle DPRs were taken of all the teeth and were then measured by the two doctors. Accuracy of teeth length made by CBCT and DPRs were compared to each other. Results For single-rooted premolars, the CBCT measurements underestimated the tooth length at every plane with no statistical significance (P > 0.05), while DPRs measurements overestimated the tooth length significantly (P < 0.05). For two-rooted premolars, the CBCT-APs measurements overestimated the teeth length, but the CBCT-SPs and CBCT-CPs underestimated the teeth length. However, these differences had not statistical significance (P > 0.05). The DPRs measurements underestimated the buccal length but overestimated the palatal length significantly (P < 0.05). There was no statistical significance between the two doctors (P > 0.05). Conclusion CBCT teeth length measurements show a strong correlation with the gold standard at every plane by different doctors, which indicated the high reliability and reproducibility of CBCT measurements.

Key words: Accuracy, Cone beam computed tomography, digital periapical radiographs, tooth measurement