ObjectiveTo investigate the feasibility and accuracy of length measurement of in vivo teeth by using cone beamCT (CBCT).MethodsBefore orthodontic extraction, 109vitalpremolars from 40 participantswere scannedby using CBCT and reconstructed by using InVivoDental software. Buccal-lingual sectional images along the long axis of teeth were then acquired, and the crown, root, and tooth length were measured separately. After careful extraction and fixation, the cor-responding length of thesametooth was measured byusing a digitalcaliper. CBCT measurement accuracywas then verified by using physical measurements as reference.Results CBCT and the physical method did not obtain significantly different measurements of the root, crown, and tooth length of experimental teeth (P=0.790, P=0.621, P=0.657, respectively), and the measurements were found to be consistent. The 95% limits of agreement of root, crown, and tooth length were -1.10 mm to
1.13mm, -1.00 mm to 0.96mm, and -1.00 mm to 1.05 mm, respectively.Conclusion The difference between CBCT and the physical method was not significant, and good consistency was shown. CBCT could be applied in noninvasive measure-ment of in vivo teeth.
