[Validity of tooth volume determinations using cone beam computed tomography].

OBJECTIVE

To determine the accuracy of volumetric analysis of teeth in vivo using cone beam computed tomography (CBCT).

METHODS

The physical volume (Vw) of 24 bicuspids extracted for orthodontic purposes (16 were imaged with the i-CAT and 8 with the CB MercuRay before extraction) was determined using water displacement technique. Corresponding pre-treatment CBCT image data were uploaded into Amira 4.0 for segmentation and radiographic volume (Va). All measurements were performed twice by two observers. The statistical difference between Vw and Va was assessed using a paired t-test. The intra- and inter-observer reliability was determined by calculating Pearson correlation coefficients and intraclass correlation coefficients (ICC).

RESULTS

The overall mean Vw of teeth specimens was (0.553 + or - 0.082) cm(3), while the mean Va was (0.548 + or - 0.079) cm(3), (0.529 + or - 0.078) cm(3) for observer 1, and (0.567 + or - 0.085) cm(3) for observer 2. There were statistically significant differences between Va and Vw (P<0.05). Between two observers, Va had statistically significant difference (P<0.05). The inter- and intra-observers correlation coefficient for Vw was high. Lastly, surface smoothing reduced the volume by 3%-12%.

CONCLUSION

In vivo determination of tooth volumes from CBCT data is feasible. The measurements slightly deviate from the physical volumes within -4% to 7%. Smoothing operations reduce volume measurements.