Introduction

A panoramic image displays the patient’s maxillary and mandibular oral and facial structures across a flat surface.¹ According to Iannucci & Howerton, "panoramic imaging is an extraoral technique that is used to examine the maxilla and mandible on a single projection." Panoramic imaging was first introduced in the 1930s, but became more popular as a diagnostic tool in the 1960s.^2,3 During the 80s, panoramic imaging transitioned to a digital format, which had the advantage of less radiation as well as immediate viewing of the image for patient education.³ Panoramic imaging enables the dentist to diagnose the entire dentition and facial structures that are not visible in a full-mouth series.⁴ The technique is considered part of the standard of care and is popular due to the relative ease of use, wide scope of examination, and low radiation dose.⁵ The guidelines presented by the American Dental Association (ADA) indicate that a panoramic image and posterior bitewings are considered an acceptable full mouth series in certain cases.⁶

Dental professionals must understand the difference between normal anatomical landmarks and abnormal findings, such as artifacts or pathology, which may be present on a panoramic image when viewing both the mandible and maxilla in the one projection. It is recommended to review the image systematically in order not to overlook anything that might be a deviation from normal.⁴ The clinician may utilize the technique that they are comfortable using; however, it must be consistent and ensure that all diagnostic information is read.² For instance, Perschbacher, recommends the following sequence: 1) review osseous structures and surrounding soft tissues, 2) review the alveolar process, and 3) review the teeth.⁴

It is important to evaluate the image bilaterally to look for symmetry, or asymmetry, which can indicate a pathological condition. For that reason, the methods suggested by Langland, Langlais, and Preece, which divides the image into 6 different zones (Figure 1), is a valuable tool for use during interpretation.³

Figure 1. Zones of Interpretation.³

Image source: Courtesy of MH & Dr. Iwata.

Table 1. Zones of Panoramic Image Interpretation.³

Zone 1: Dentition	Teeth arranged with an upward smile-like curve Anterior teeth should not be too large or small Posterior teeth should be evenly sized without excessive overlap Apices/crowns of teeth should be visible
Zone 2: Nose & Sinus	Inferior turbinates and surrounding air spaces visible Soft tissue of nose should not be visible Shadow of hard palate will be seen in maxillary area Tongue should be in contact with hard palate
Zone 3: Mandibular Body	Inferior border of mandible should be continuous and smooth Ghost image of hyoid should not be visible Midline area should have proper proportions
Zone 4: Condyles	Condyles should be centered within the area of the zone Condyles should be of equal size and on same horizontal plane
Zone 5: Ramus & Spine	Ramus of mandible should be similar width bilaterally Spine, if seen, may be present as long as it doesn’t superimpose over the ramus If spine is present, the distance between the ramus and spine should be equivalent on both sides
Zone 6: Hyoid Bone	Hyoid bone should appear as a bilateral, double image with equal proportions Hyoid image may touch the mandible, but should not spread across it

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