In most areas of the jaw, the lesion becomes evident radiographically when which occurs?

• A. Cortical bone has resorbed
• B. Trabecular bone has resorbed
• C. Periosteal reaction develops
• D. Sclerosis occurs

Answer: (A)

The main concept is that radiographic visibility of a jaw lesion hinges on destruction of the cortical bone. The outer cortex is the dense, radiopaque shield on X-rays; when a lesion grows and resorbs this cortex, it creates an opening and a noticeable radiolucent area that outlines the lesion. If the cortex remains intact, changes within the inner cancellous (trabecular) bone may be masked by the surrounding dense cortical shell and by the trabecular pattern, so the lesion may not be readily seen on radiographs. Periosteal reactions or sclerosis can appear later or in different contexts and aren’t the first signs that reveal a lesion in most jaw areas. Therefore, cortical bone resorption makes the lesion radiographically evident.