26.2
Extraoral Projection Techniques
The techniques for extraoral projection include:
- Lateral jaw imaging
- Skull imaging
- Extraoral bite-wing imaging
- Temporomandibular joint imaging
- A variety of projection techniques are used in extraoral imaging
Lateral Jaw Imaging
Lateral jaw imaging is used to examine the posterior region of the mandible, which includes the body and the ramus of the mandible. It can be used on children, is not commonly used in dental offices, and a standard intraoral X-ray machine can be used. Learn more about the body and the ramus mandible in the slides below.
Skull Imaging
Skull imaging is used to examine the bones of the face and skull, can be difficult to interpret, and is mostly often used in oral surgery and orthodontics.
Skull imaging includes:
- Lateral cephalometric projection: the most common type of skull image
- Posteroanterior projection
- Waters projection
- Submentovertex projection
- Reverse Towne projection
- Temporomandibular joint (TMJ)
Learn more about the projections in the slides below.
Extraoral Bite-Wing Imaging
The purpose of this procedure is to provide diagnostic information about the maxillary and mandibular teeth, interproximal regions, the periapical bone, and surrounding structures. This imaging technique is similar to traditional bite-wing images but offers a larger view of anatomical structures.
The receptor is placed according to the manufacturer’s recommendations for panoramic imaging.
The head should be positioned with the Frankfort plane parallel to the floor, the midsagittal plane perpendicular to the floor, and the anterior teeth on the bite stick, which places the teeth into the focal trough.
Beam alignment is dependent on the specific panoramic machine being used.
Exposure factors vary with the type of receptor and equipment used. Adjustments can be made for children, teenagers, and adults, as well as for different jaw sizes. It should be noted that errors seen with panoramic imaging may also be observed when exposing extraoral bite-wing images.
Temporomandibular Joint Imaging
The joint includes the temporal bone and the mandible. The glenoid fossa and articular eminence of the temporal bone, the condyle of the mandible, and the articular disk between the bones comprise the temporomandibular joint (TMJ), also known as the jaw joint. Patients are usually referred to a specialist who will obtain the special imaging techniques necessary for diagnosis. These techniques include transcranial projection and temporomandibular joint tomography.
Learn more about the techniques in the slides below.
