ABSTRACT
<p><b>OBJECTIVE</b>To investigate the feasibility and accuracy of length measurement of in vivo teeth by using cone beam CT (CBCT).</p><p><b>METHODS</b>Before orthodontic extraction, 109 vital premolars from 40 participants were scanned by 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 corresponding length of the same tooth was measured by using a digital caliper. CBCT measurement accuracy was then verified by using physical measurements as reference.</p><p><b>RESULTS</b>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 1.13 mm, -1.00 mm to 0.96 mm, and -1.00 mm to 1.05 mm, respectively.</p><p><b>CONCLUSION</b>The difference between CBCT and the physical method was not significant, and good consistency was shown. CBCT could be applied in noninvasive measurement of in vivo teeth.</p>