Bioquimica

ak radiographic anatomy and common alies seenin cephalometricjilms
%?i L. Kantor, D.D.S.,* and Louis A. Norton, D.M.D.**
Ghapel HZ, N.C., and Farmington, Corm. Lateral and posteroanterior cephalometric radiographs are used routinely in the diagnosis and quantification of dentofacial anomalies that require orthodontic treatment. The anatomic information that these films contain is occasionallyoverlooked as the clinician prepares tracings and makes measurements. With the increase of the average age of the orthodontic patient population, there is greater likelihood of the presence of disease. This article describes some important features of rnormal radiologic anatomy of the head and neck so that a clinician can better recognize pathologic changes. Common pathologic findings and anatomicanomalies are also illustrated. (AM J Ow~at? DENTOFAC ORTHOP 1987;91:414-26.) !Key words: Cephalometrics, radiographic anatomy, radiographic anomalies, diagnosis

ring the course of evaluation

and treat-

image does not change, but the amount of information
that can be retrieved from each image is greatly affected

dontist often takes cephalometric radiographs of the patient’s skull. Amathematic analysis is usually done to help diagnose and quantify skeletal and dental malocclusions, make growth predictions, or monitor the patient’s treatment progress. However, fortuitous findings must not be overlooked or ignored. The clinician should evaluate the skull radiographs for any abnormahties that might be present. To assist the orthodontist with this responsibility, we will reviewnormal radiographic anatomy of the human skull emphasizing a systematic approach to interpretation. Examples illustrating variations of normal anatomy that may be mistaken for pathosis are provided as well as examples of pathologic changes that are often overlooked. No attempt will be made to illustrate the full range and distribution of normal anatomy in this limited review. References dealing withthis subject are cited.

The information content of a radiograph is a complex function of film/screen selection, technique factors, processing, and patient anatomy. The first three of these parameters can be controlled and should be optimized to ensure the best radiographic image with the least patient exposure. However, once a radiograph is processed the amount of information recorded in the*Previously\hith the Division of Oral Radiology, University of Connecticut School of Dental Medicine; currently in the Sectionof Oral Radiology, University of North CarolJnaSchoolof Dentistry. “*Department of Orthodontics, University of ConnecticutSchool of Dental Medicine.

by the circumstances under which the film is viewed. ‘,2 Reduced ambient lighting, quiet surroundings, and theelimination of peripheral light improve visual a~uity.~,~ Kundel and Nodine have described two modes of visual perception of radiographs. First is “global perception” resulting from rapid parallel processing of the entire retinal image by means of pattern recognition and rapid association with previously acquired visual concepts. The second is “analytic perception,” which is based on the extraction offeatures from the incoming visual data and the use of logical rules to combine them in a meaningful way. This technique results in a gradual buildup of the perception. They suggest that experienced radiologists perceive abnormalities in a global manner and that specific features are perceived secondarily. The experienced orthodontist can often rapidly scan a cephalometric film and tell whether apatient has a dental or skeletal problem or a combination of the two and what part of the anatomy is contributing the most to the problem. The cephajiometric analysis usually corroborates this global impression and quantitates a qualitative judgment. Christensen and associates6 evaluated the effect of search time on perception and found that obvious abnormalities are detected almost instantaneously...