October 1, 2010
by Dr. Susanne Perschbacher, DDS, MSC, DIP. ABOMR, FRCD(C) Oral and Maxillofacial Radiology. Dr. Persch
Comment on an article published May, 2010: Small Focal Field Volumetric Cone Beam Tomography: The new standard of Care in Foundational Dentistry? by Dr. F. Barnett and Dr. K. Serota
would like to thank Drs. Barnett and Serota for highlighting some of the clinical scenarios when Cone Beam Computed Tomography (CBCT) can be a valuable tool in aiding diagnosis and treatment planning for endodontic patients. There is little doubt that, when applied responsibly, there are many instances where CBCT provides information unavailable by other means because of its ability to demonstrate anatomy in all planes. I would like, however, to provide a correction and a comment regarding some of the content of the article.
In the case presented in figures 2A and B the authors identify “a circumscribe radiopaque lesion” on a panoramic radiograph. They suggest a differential diagnosis of “juvenile or cemento-ossifying fibroma (fibrous dysplasia), Stafne’s idiopathic bone cavity or a giant-cell granuloma”. In order that readers of Oral Health are not misinformed, I would first like to point out that fibrous dysplasia is not the same as a cemento-ossifying fibroma. The former is a type of bone dysplasia; an alteration in the bone architecture into a fibro-osseous mixture, which tends to cause localized expansion during the years of active growth and to become stable after puberty. A cemento-ossifying fibroma is a benign tumour with continued growth potential and, especially in the juvenile form, often presents as an aggressive swelling with displacement of cortices and neighboring teeth. Additionally, Stafne’s idiopathic bone cavities are always radiolucent because they are a localized concavity in the bone (please refer to the Diagnostic Challenge presented in this issue on pages 60, 64-65). Finally, central giant cell granulomas present radiographically as multilocular radiolucent lesions which tend to cause expansion and root resorption. In any case, none of these lesions are of endodontic origin.
The round radiopacity presented in this article represents a dense bone island (idiopathic osteosclerosis). Dense bone islands are a common variation of normal and, in this case, could have been diagnosed from the panoramic radiograph. It is important that, as we embrace the value of CBCT technology, we do not lose sight of our responsibility to prescribe this examination appropriately. Exposure to diagnostic x-rays, whether periapical or panoramic radiographs or a CBCT, can be justified when the patient is expected to receive a benefit, in the form of a more accurate diagnosis or treatment plan, which cannot be obtained by other non-invasive means. Younger individuals, such as the one presented in this case, are more susceptible to the risks from exposure to ionizing radiation because their tissues are more immature and they carry the burden of any damage received over a longer time.
The authors point out that recommendations were made regarding appropriate patient selection and quality assurance when panoramic radiography became widely available. Today, however, panoramic radiographs have become the most overused, poorly taken and incompletely interpreted images in dentistry. Without appropriate steps to educate practitioners and protect the public, we are entering an era where CBCT, along with its wonderful applications, risks following a similarly abused path. OH