Practical Panoramic Imaging
Course Number: 589
Course Contents
Features of an Optimal Panoramic Image
There are two general features that distinguish this panoramic from a poor one: adequate exposure and correct anatomic representation.
Figure 26. Optimal Panoramic Image.
Example of an excellent edentulous panoramic radiographic image with adequate exposure and correct anatomic representation.
Adequate exposure. An assessment of adequate exposure implies that there is adequate density (overall darkness) and contrast (differences in density) to recognize anatomic features.
Density. The ideal density should be such that structures are not obstructed by areas of darkness i.e. areas of “burn out” or areas that are too light i.e. areas of “white out”. Visually this can be assessed by looking at the mandibular parasymphyseal area and region associated with the apices of the maxillary teeth. In the maxilla this is most evident when the tongue is not held in proper position during panoramic exposure.
Excessive or inadequate density
can lead to failure to detect features such as unerupted and impacted teeth or even pathology. A dark or high-density image is usually caused by overestimation of the patient’s overall size, stature, and bone density while a light or low-density image is usually caused by underestimation of the patient’s overall size, stature, and bone density.
Figure 27. Density Assessment.
Regions on a panoramic image to examine to determine adequate density
Figure 28. Overexposure.
Example of an overtly dark, overexposed panoramic image.
Excessive Exposure Examples:
Images demonstrating how excessive exposure can lead to failure to detect pathologic features. The image on the right is a digitally enhanced version of the left overexposed panoramic radiograph and clearly demonstrates the appearance of a radiolucent region causing expansion and thinning of the inferior cortex of the right mandible – features that were not evident on the original.
Figure 29A. Original Panoramic Image.
Figure 29B. Enhanced Panoramic Image
Images demonstrating how excessive exposure can lead to failure to detect pathologic features. The image on the right is a digitally enhanced version of the left overexposed panoramic radiograph and clearly demonstrates the appearance of a radiolucent region causing expansion and thinning of the inferior cortex of the right mandible – features that were not evident on the original.
Underexposure Examples:
Images demonstrating how inadequate exposure can lead to failure to detect pathologic features. The image on the right is a digitally enhanced version and clearly demonstrates the appearance of an impacted mandibular right third molar that was not readily apparent on the original (left). This enhancement also clearly demonstrates a large pericoronal lesion that involves the right mandibular third molar.
Figure 30A. Original Panoramic Image.
Figure 30B. Enhanced Panoramic Image.
Images demonstrating how inadequate exposure can lead to failure to detect pathologic features. The image on the right is a digitally enhanced version and clearly demonstrates the appearance of an impacted mandibular right third molar that was not readily apparent on the original (left). This enhancement also clearly demonstrates a large pericoronal lesion that involves the right mandibular third molar.
Contrast. The second element of adequate exposure assessment is contrast. This can best be assessed by determining if the interface between the enamel and the dentin can be seen, usually in the molar region. The dentinoenamel junction (DEJ) should be apparent.
Figure 31. Contrast Assessment. DEJ evaluation for panoramic image contrast.