Measurement of the bone height of mandibular incisors and canines on computed tomography-Limitations according to bone thickness.

Aim: To verify the correlation between cone beam CT (CBCT) and spiral CT (SCT) images and direct measurement of the bone height and to verify whether bone thickness (BT) influences the accuracy of bone height measurement on CT.

Setting And Sample: One hundred and fourteen measurements were obtained in 10 dry human mandibles.

Materials And Methods: The alveolar bone height was measured on volumetric and linear images.

Results: Negative, average and significant correlations (-0.622** to -0.489**) were verified between BT and the absolute error. When the alveolar bone thickness was at least 0.6 mm, the mean differences were 0.16 and 0.28 mm on linear images and 0.12 and 0.03 mm on volumetric images for CBCT and SCT. Additionally, these values ranged from -0.46 to 0.79 and -0.32 to 0.88 mm on linear images and from -0.64 to 0.67 and -0.57 to 0.62 mm on volumetric images for CBCT and SCT. When the alveolar bone thickness was less than 0.6 mm, the CT evaluation varied from -1.74 to 5.42 and -1.64 to 5.42 mm on linear images and from -3.70 to 4.28 mm and -3.49 to 4.25 mm on volumetric images for CBCT and SCT.

Conclusions: Spiral CT and CBCT images demonstrate significant correlation with direct measurement for the alveolar bone height. Measurement of the alveolar bone labial and lingual to the mandibular incisors and canines presented higher accuracy when its thickness was greater than 0.6 mm. When the thickness was less than 0.6 mm, bone dehiscence can be diagnosed despite bone being clinically present.