Pan, Pan-ceph & 3D

The most common types of dental X-rays are captured using conventional 2D equipment described on our Digital Sensors page:

  • Bitewing – taken during most routine dental check-ups and are useful for revealing dental cavities between the teeth.
  • Periapical – show the entire tooth, including the roots, as well as the bone surrounding them. These X-rays are useful in helping to diagnose a dental abscess as well as periodontal gum disease.
More advanced types of X-rays are summarized here:
  • Panoramic – shows dentists the Big Picture, a broad overview of the entire mouth.
  • Panoramic Cephalogram (pan-ceph)
  • 3D Cone Beam Computed Tomography (CBCT) – the standard of care for implantologists, orthodontists, periodontists and oral/maxillo-facial surgeons.
Panoramic

The panoramic X-ray supplies information about the teeth, upper and lower jawbone, sinuses, and other hard and soft tissues of the head and neck. One advantage of the panoramic X-ray is its ease of use. Unlike other X-rays where the film is placed inside the patient’s mouth, the panoramic film is contained in a machine that moves around the patient’s head. Some people may be familiar with the panoramic X-ray because it is usually taken when the wisdom teeth are being evaluated. The X-ray will also reveal deep cavities and dental gum disease, but it is not as precise as bitewing or periapical X-rays.

The panoramic X-ray has many other applications, including evaluating patients with past or present TMJ or jaw joint problems; those who require full or partial removable dentures, dental implants or dental braces; those who are at risk or suspected of having oral cancer symptoms or other tumors of the jaw, have impacted teeth (especially impacted wisdom teeth) or have had any recent trauma to the face or teeth (i.e. can help identify a fractured jaw); and for those who can not tolerate other types of films (severe gaggers).The panoramic X-ray can also identify some not so common problems, such as calcification within the carotid artery that may indicate the potential for a stroke. In one unusual situation, I can recall a patient who mentioned that he had suffered for years with recurrent sinus infections. I took a panoramic X-ray that revealed an infected tooth–upside-down and stuck in his sinus!

The panoramic X-ray is an important part of a thorough dental examination. I usually recommend a panoramic X-ray once every five to seven years for most patients. Although the panoramic X-ray does not provide as much detail when evaluating the teeth and gums as other dental X-rays, it can pick-up potential problems that the other x-rays cannot.

Panoramic Cephalogram (pan-ceph)

The pan-ceph X-ray is a full lateral high-contrast view of the bony tissues of the head including the mandible, used to make accurate volumetric measurements, evaluate dentofacial proportions and clarify the anatomic basis for a malocclusion. For most orthodontics cases, a lateral pan-ceph contains much information regarding the location and angulation of unerupted teeth.

3D Cone Beam Computed Tomography (CBCT)

Older traditional CT (CAT scan) uses a narrow fan beam that rotates around the patient acquiring thin axial slices with each revolution. In order to create a section of anatomy, many rotations must be done. During these repeated rotations, traditional CT emits a high radiation dose, but it leaves a gap of information between each rotation. Therefore software must “stitch” together the images and calculate what is missing.

Cone Beam 3D imaging uses a cone-shaped beam to acquire the entire image in a single scan using only one rotation. The result is a more accurate image without missing information and a considerably lower radiation exposure.

The scanner’s accuracy is determined by the range of its grey scale, and the granularity of the image measured in voxel size (Volumetric Picture Element). A voxel represents a 3D cube in a cell of a grid. This is analogous to a pixel, which represents 2D image data in a plane.

The scanner’s Field Of View(FOV) determines how much of the patient’s anatomy will be visualized. The dimensions of the cylindrical FOV can be described as Diameter by Height(DxH). The size of FOV can typically vary from 6×6 cm up to 15×15 cm and can be selected directly from the software, before the scan.

The use of a small FOV (on user-defined region in endo, perio, implant surveys and for the localization of impacted teeth) in addition to reducing the dimension of the irradiated region, allows for a dramatic increase in the accuracy and resolution of images where it is necessary to identify very small details at high definition. In contrast, where appropriate for diagnosis, the largest FOV includes the roof of the orbits and the Nasion down to the hyoid bone. This allows with single-rotation scanning of patients where the doctor needs to see the major part of the anatomical regions of the head (e.g. Orthodontics, Orthognatics and Maxillofacial surgeons, etc.). Advanced software calculates the proper balance between FOV, dose and accuracy, using different dose protocols for each single FOV. Medium FOV are also selectable for ENT, TMJ, pano’s and implant surveys.

Treatment planning is improved through 3D computerized modeling of the movement of teeth. The 3D scene allows combination of hard and soft tissue representations. Tissue landmarks can be precisely positioned, visualized, and combined to form anatomical planes. The clear definition and separation of the teeth from the surrounding anatomy via image segmentation enhances the doctor’s ability to “see” and, if needed simulate “movement” of the teeth onscreen.

Design of surgical guides is improved through 3D computerized modeling. The precise depth and density of bone can be assessed, and the implant bed can be checked in all dimensions. The position of an implant relative to the sinuses, mandibular canal, and other structures can be measured and modeled to promote a satisfactory outcome.

Please click on one of our advanced imaging products to the right for specific product information.

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