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CAD/CAM - international magazine of digital dentistry, Italian Edition, No.1, 2017

research _ computed tomography Sagittal tomographic cuts Cut 1 Cut 2 Cut 3 Cut 4 Cut 5 Cut 6 Cut 7 Cut 8 Cut 9 Cut 10 Cut 11 Cut 12 Cut 13 Cut 14 Cut 15 Cut 16 Cut 17 Cut 18 Radiographic measurements (n = 39) Mean ± SD† Bone measurements (n = 39) Mean ± SD Discrepancies Mean ± SD 24.53 ± 3.88 24.96 ± 3.93 -0.42 ± 1.11 24.61 ± 4.02 25.16 ± 3.98 -0.55 ± 1.11 25.13 ± 4.15 25.98 ± 4.19 -0.84 ± 1.07 26.07 ± 4.08 27.31 ± 4.05 -1.23 ± 1.21 27.71 ± 4.22 29.17 ± 4.35 -1.46 ± 1.26 29.67 ± 4.30 30.61 ± 4.31 -0.92 ± 1.15 29.53 ± 4.21 30.29 ± 4.36 -0.75 ± 1.31 29.38 ± 4.35 30.09 ± 4.43 -0.71 ± 1.16 29.34 ± 4.47 30.11 ± 4.74 -0.77 ± 1.53 29.41 ± 4.55 30.24 ± 4.62 -0.82 ± 1.15 29.25 ± 4.36 30.17 ± 4.45 -0.92 ± 1.18 29.26 ± 4.37 29.83 ± 4.55 -0.56 ± 1.36 28.67 ± 4.62 29.51 ± 4.65 -0.83 ± 1.13 27.26 ± 4.83 28.29 ± 4.91 -1.03 ± 1.37 26.14 ± 4.89 27.02 ± 4.75 -0.87 ± 1.26 25.14 ± 4.94 25.94 ± 4.71 -0.79 ± 1.46 24.71 ± 4.83 25.37 ± 4.78 -0.66 ± 1.25 24.73 ± 4.84 25.64 ± 4.64 -0.91 ± 0.41 p-value 0.064 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 0.001 < 0.001 < 0.001 < 0.001 < 0.001 0.004 < 0.001 † SD = standard deviation. Table 2_Discrepancies between radiographic measurements (mm) and measurements taken directly from the bone (mm) using the basal plane as the axial reference plane (Student’s t-test). 20 1_2017 the axial reference plane, discrepancies were found in all of the tomographic slices as- sessed. These discrepancies were positive in nine (50%) of the slices, while in the remaining nine (50%), the measurements taken from the CT scans were lower than the measure- ments taken from the bone. In six of the 18 slices analyzed (33.33%), the discrepancies observed showed statistically significant dif- ferences (p ≤ 0.05; Table 1). When the basal plane was used as the axial reference plane, discrepancies were also found between mea- surements taken from tomographic slices and clinical measurements of the mandibles in all 18 slices analyzed. These discrepancies were negative in all cases. In 17 of the slices (94.44%), the dis- crepancies showed statistically significant differences (p ≤ 0.05; Table 2). In this sense, with regard to positioning the patient when the CT scans were taken, use of the occlusal plane as axial reference produced the most accurate measurements (Fig. 4). When the distribution of discrepancies in millimeters found in each of the 18 tomo- graphic slices was compared in relation to the axial reference plane, a higher percent- age (99.44%) of discrepancies greater than

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