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Occlusal radiographs in the mandibular arch are properly executed by tipping the patient’s head backwards and pointing the X‐ray tube at right angles to a receptor held between the teeth in the occlusal plane (Figure 4.1). The head will need to be tipped back to permit the positioning of the X‐ray tube under the chin. In the lower canine/premolar region, the occlusal view is a ‘true’ occlusal view and should depict all the posterior standing teeth in cross‐section, thereby providing bucco‐lingual positional information on the tooth and any associated structures in a plane at right angles to that seen on the periapical radiograph. Due to the thickness of bone traversed, detail is much poorer, unless there is expansion owing to a large cyst or a bucco‐lingually displaced tooth.

Fig. 4.1 The angle of the central ray in a true occlusal view of the lower jaw depends on the area of interest.

Source: Reproduced from previous edition. Adrian Becker, The Orthodontic Treatment of Impacted Teeth, 2nd ed., 2007 with the kind permission of Informa Healthcare – Books.

In order to produce a true occlusal view in the anterior region of the mandibular arch (Figure 4.1), the head will need to be tipped back further and the tube pointed at the symphysis menti, at an angle of 110° to the occlusal plane, in line with the long axes of the incisor teeth. To achieve the same for the molar teeth, the 90° angle to the occlusal plane will need to be augmented by a 15° medial tilt of the tube, to compensate for the characteristic slight lingual tipping of these teeth [3]. This means that, ideally, the radiograph should be performed individually for each side, in order to capture each molar in its long axis and its true occlusal view.