9: Occlusal radiography

Occlusal radiography

Occlusal radiography is defined as those intraoral radiographic techniques taken using a dental X-ray set where the image receptor (film packet or digital phosphor plate – 5.7 × 7.6 cm) is placed in the occlusal plane. Suitable sized solid-state digital sensors are not currently available.

Terminology and classification

The terminology used in occlusal radiography is very confusing. The British Standards Glossary of Dental Terms (BS 4492: 1983) is inadequate in defining the various occlusal projections and in differentiating between them. The result is that there is still little uniformity in terminology among different publications and teaching institutions.

The terminology used here is based broadly on the British Standards terms, but they have been modified in an attempt to make them more explicit, straightforward and practical.

Maxillary occlusal projections

• Upper standard (or anterior) occlusal (standard occlusal)

• Upper oblique occlusal (oblique occlusal)

• Vertex occlusal (vertex occlusal) – no longer used.

Mandibular occlusal projections

• Lower 90° occlusal (true occlusal)

• Lower 45° (or anterior) occlusal (standard occlusal)

• Lower oblique occlusal (oblique occlusal).

Upper standard (or anterior) occlusal

This projection shows the anterior part of the maxilla and the upper anterior teeth.

Main clinical indications

The main clinical indications include:

• Periapical assessment of the upper anterior teeth, especially in children but also in adults unable to tolerate periapical holders

• Detecting the presence of unerupted canines, supernumeraries and odontomes

• As the midline view, when using the parallax method for determining the bucco/palatal position of unerupted canines

• Evaluation of the size and extent of lesions such as cysts or tumours in the anterior maxilla

• Assessment of fractures of the anterior teeth and alveolar bone.

Technique and positioning

The technique can be summarized as follows:

1. The patient is seated with the head supported and with the occlusal plane horizontal and parallel to the floor and is asked to support a protective thyroid shield.

2. The image receptor, suitably barrier wrapped, is placed flat into the mouth on to the occlusal surfaces of the lower teeth. The patient is asked to bite together gently. The image receptor is placed centrally in the mouth with its long axis crossways in adults and anteroposteriorly in children.

3. The X-ray tubehead is positioned above the patient in the midline, aiming downwards through the bridge of the nose at an angle of 65°–70° to the image receptor (see Fig. 9.1).

Fig. 9.1 A Diagram showing the position of the image receptor in relation to the lower arch. B Positioning from the front; note the use of the protective thyroid shield. C Positioning from the side. D Diagram showing the positioning from the side. The resultant radiograph is shown in Fig. 9.2.

Fig. 9.2 An example of an upper standard occlusal radiograph with the main anatomical features indicated.

Upper oblique occlusal

This projection shows the posterior part of the maxilla and the upper posterior teeth on one side.

Main clinical indications

• Periapical assessment of the upper posterior teeth, especially in adults unable to tolerate periapical image receptors

• Evaluation of the size and extent of lesions such as cysts, tumours or osteodystrophies affecting the posterior maxilla

• Assessment of the condition of the antral floor

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Tags: Radiography and Radiology for Dental Care Professionals 3e

Jan 12, 2015 | Posted by mrzezo in Oral and Maxillofacial Radiology | Comments Off

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