Figure 17a. Squamous cell carcinoma of the oral cavity invading the mandible. (a) Transverse view shows destruction (arrowheads) of the mandible and cortex, without expansion of the jaw. Note involvement of the mandibular canal (arrow). Compare these findings with those on the normal left side. (b) Cross-sectional dental CT scans again show destruction of the cortex (arrowheads) and involvement of the superior aspect of the mandibular canal (arrow). Note that signs of a benign lesion, bone expansion, and mandibular canal displacement are absent in this malignancy. Compare these findings with those of the benign lesion in Figure 15c.