Occlusal radiography
Lower 45° occlusal This projection is taken to show the lower anterior teeth and the anterior part of the mandible. The resultant radiograph resembles a large bisected angle technique periapical of this region. Main clinical indications • Periapical assessment of the lower incisor teeth, especially useful in adults and children unable to tolerate periapical films • Evaluation of the size and extent of lesions such as cysts or tumours affecting the anterior part of the mandible • Assessment of displacement fractures of the anterior mandible in the vertical plane.
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Technique and positioning 1. The patient is seated with the head supported and with the occlusal plane horizontal and parallel to the floor. 2. The film packet, with the white (pebbly) surface facing downwards, is placed centrally into the mouth, on to the occlusal surfaces of the lower teeth, with its long axis anteroposteriorly, and the patient is asked to bite gently together. 3. The X-ray tubehead is positioned in the midline, centring through the chin point, at an angle of 45° to the film (see Fig. 10.9).
Fig. 10.9A Diagram showing the position of the film packet (white pebbly surface facing downwards) in relation to the lower arch. B Positioning for the lower 45° occlusal from the side. C Diagram showing the positioning from the side. Resultant radiograph
Fig. 10.10 An example of a lower 45° occlusal radiograph with the main radiographic features indicated.