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FIG 4. On comparable cross sections, defined distances and diameters were measured on dental MR images and CT scans and by direct osteometry. Two sets of measurements were obtained in every quadrant of the mandibles: the first set was taken from the cross-sectional slice at the level through the mental foramen, the second from the cross-sectional slice at a point 15 mm posterior to the mental foramen. The following distances were measured: ABL, the longest axis in the bucco-lingual direction of the cross section; AAB, the longest axis in the apico-basal direction of a cross section; DTT, the distance from the top of the foramen (set 1) or top of the mandibular canal (set 2) to the top of the alveolar ridge; DBB, the distance from the bottom of the foramen (set 1) or bottom of the mandibular canal (set 2) to the base of the mandible; and DBC, the diameter of the bone cortex at the alveolar ridge.
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