Dental Panoramic Tomogram or OPG is a sophisticated x-ray machine used to take radiographic images of the teeth and jaws bone which is in a arch position. We used to call this machine as OPG (which stands for ORTHOPANTOGRAM), which was named after the first x-ray unit.
OPG performed by using a technique called “tomography”.
The X-ray tube moves around the head, the x-ray film moves in the opposite direction behind your head. This generates an image slice where the mandible and teeth are in focus, and the other structures are blurred.
The anatomy consists of the body, ramus and angle of mandible, coronoid process, mandibular notch, condyle of mandible, alveolar ridge, symphysis menti, maxillary sinuses, nasal fossae and 16 upper and 16 lower teeth, as shown in the image below.
Reasons for OPG requests
- Caries – appear as different shaped areas of radiolucency in the crowns or necks of teeth.
- Peridontioiditis – when inflammation extends into the underlying alveolar bone and there is a loss of attachment.
- Peridontal Abscess – Radiolucent area surrounding the roots of the teeth.
Impacted or embedded teeth (eg. wisdom teeth)
- OPG shows angulation, shape of roots, size and shape of crown, effect on other teeth.
- To look for impacted canine
- Eg. Developmental, to show size, number, shape and position.
Lesions in the jaw bone
- Cyst of jaw bone – shape, size, extension, involving nearby structure
- Tumour/growth – benign, malignant
Trauma to teeth and facial skeleton
- Mandible fractures are often bilateral.
- Panoramic view of mandible to view the fracture.
- Determine site and direction of fracture lines.
- Relationship of teeth to fracture lines.
- Alignment of bone fragments after healing.
- Evidence of infection or other complications post intervention.
- Follow up to assess healing.
Planing for implant placement
- To identify the position and location for implant placement
- Bone quality and quantity
- Anatomical structure that should be avoided such as the maxillary sinus and the inferior dental nerve