Interpreting an orthopantomogram

An orthopantomogram (OPG) is a common radiograph used to identify the hard tissues of the oral cavity and surrounding skeletal structures. It is an extra-oral radiograph that approximates the focal trough of the mandible. Although resolution is not as detailed as intra-oral radiographs for examination of the teeth, gross changes in calcification of the dental structures, and changes in ossification of the underlying mandible and maxilla can aid in identification of dental disease such as caries (decay), periodontal bone loss, and abscess and cyst formation.

This article outlines key anatomical features identifiable in an OPG and illustrates some common pathology that may be seen.

The large amount of data visible on an OPG may appear daunting to the viewer unless a systematic approach is used to examine structures present. Distortion due to flattening of the curve of the mandible and dentition will give an overall view of these structures and requires the viewer to reinterpret these in their mind for a three-dimensional appreciation of the image.