PERIOSTEAL NEW BONE-FORMATION IN THE JAWS - A COMPUTED TOMOGRAPHIC STUDY

Objectives: To investigate the diagnostic significance of a periosteal reaction (PR) in diseases of the jaws. Methods: The frequency of PR w as investigated in 1142 patients who had undergone CT of the maxilla o r mandible. The pattern of PR was categorized as either parallel, irre gular, spicule or Codman's triangle. We examined the relationship of t he pattern of PR to the specific disease categories of osteomyelitis, trauma, cysts, benign tumours and malignant tumors. Results: Seventy p atients were found to have PR. It was found in 40% of cases with osteo myelitis and 15% of malignant tumors. The only benign lesion was an eo sinophilic granuloma. There were no cysts. The frequency of PR was hig her in younger patient and in those with sarcomas or bone metastases c ompared with those with carcinomas. Ninety-one percent of the patients with osteomyelitis showed single or multi-layered PR parallel to the cortical bone, while 61% of those with malignant tumors had a spicule pattern. With the exception of Codman's triangle, none of the PR patte rns were specifically associated with any one disease category. When t he PR pattern was combined with the pattern of cortical bone destructi on, 90% of the patients with PR could be correctly assigned to one or other of the four disease categories of osteomyelitis, trauma, benign lesion or malignant tumor. Conclusions: The pattern of PR on CT in com bination with the pattern of the cortical destruction of the cortex is useful in differentiating osteomyelitis from malignant tumors.