Borders:
Benign lesions tend to have smooth, well-defined borders. This means the borders are easily traceable with a distinct beginning and end to the lesion.On the other hand, malignant lesions are generally poorly demarcated, reflecting their infiltrating and destructive nature. The borders of malignancies will often appear 'fuzzy' or 'jagged.'Cortex:
When benign lesions involve the adjacent cortices of the mandible or maxilla, the cortex will be thinned and expanded. In these cases, the cortex will still be continuous, even if just barely visible.With malignant lesions, often the cortex will be destroyed or perforated. Sometimes a 'periosteal reaction' will also develop (a formation of a new, thin layer of bone along the outside of the cortex).Teeth:
Benign lesions can displace or resorb adjacent teeth; however, root resorption also occurs in malignant lesions!'Floating' teeth can appear in the presence of malignant lesions. This is where the supporting bone and associated structures around the teeth have been destroyed, leaving a tooth that appears to be 'floating' in space. Malignant lesions also may invade into the PDL space, resulting in irregular and nonconcentric widening of the PDL space.