An OPG, short for orthopantomogram, is a panoramic X-ray that captures your entire mouth, jaw, and surrounding facial structures in a single image. Unlike the small X-rays your dentist places inside your mouth, an OPG is taken from outside with a machine that rotates around your head. The result is a wide, flat image showing all your teeth, both jawbones, your sinuses, and the joints where your jaw connects to your skull.
What an OPG Shows
The strength of an OPG is its broad view. In one image, your dentist or surgeon can see the full upper and lower jaw, all teeth (including ones that haven’t come through yet), the nasal cavity, the hard palate separating your nose from your mouth, the maxillary sinuses above your upper back teeth, and the cheekbones. The nerve canal running through your lower jaw, which carries the main nerve supplying sensation to your chin and lip, is also visible as a faint channel bordered by two white lines.
This makes an OPG useful for a wide range of assessments: checking overall dental health, evaluating bone loss from gum disease, spotting infections at tooth roots, planning wisdom tooth removal, preparing for dental implants, assessing jaw fractures after trauma, and diagnosing problems with the jaw joint. Orthodontists also use OPGs to map tooth positions before braces or aligners.
What to Expect During the Scan
An OPG is quick and painless. You stand or sit in front of the machine and place your chin on a small rest while forehead and side supports hold your head still. You may be given a small bite block to open your mouth slightly, which helps separate the upper and lower teeth in the image. The technologist will ask you to remove earrings, glasses, necklaces, and any other metal objects near your head, since these show up on the X-ray and can obscure important details.
Once you’re positioned, the X-ray arm swings in a slow arc around your head, typically taking about 15 to 20 seconds to complete the rotation. You need to stay completely still during this time. A lead apron may be placed over your torso as an added precaution. The entire appointment, from walking in to walking out, usually takes only a few minutes.
Radiation Exposure
An OPG delivers a very low dose of radiation, typically between 4 and 30 microsieverts. To put that in perspective, you receive about 7 microsieverts of background radiation simply from living on Earth for a single day. Modern digital OPG machines have reduced doses further compared to older film-based systems, with some units recording effective doses as low as roughly 9 microsieverts per scan.
Digital systems also eliminate the need for chemical processing in a darkroom, producing images almost instantly on a computer screen. This means your dentist can review the results with you right away rather than waiting for film to develop. Digital images can also be enhanced, zoomed, and shared electronically with specialists.
Where an OPG Falls Short
Because an OPG flattens a curved, three-dimensional jaw into a two-dimensional image, it comes with trade-offs. The image can distort the size and shape of teeth, particularly in the front of the mouth, and overlapping structures sometimes make fine details hard to read. For detecting cavities between teeth, bitewing X-rays (the small ones placed inside your mouth) are consistently more accurate. A systematic review of diagnostic studies found bitewing radiographs superior to panoramic images for picking up cavities overall, especially between teeth where decay commonly starts.
For this reason, an OPG is rarely used alone. Dentists treat it as a screening tool that gives the big picture, then follow up with smaller, targeted X-rays or a 3D cone-beam CT scan when they need finer detail for a specific tooth or area. If you’re having a single tooth investigated for a possible crack or root canal issue, a periapical X-ray focused on that tooth will give a much sharper result.
When Your Dentist Orders One
You’re most likely to have an OPG taken during your first visit with a new dentist, as it gives them a baseline view of your entire mouth. After that, repeat OPGs are ordered based on need rather than on a fixed schedule. Common reasons include monitoring impacted wisdom teeth, tracking bone levels if you have gum disease, planning for implants or orthodontic work, and evaluating jaw pain or clicking in the joint.
If you’re pregnant, let the dental team know before the scan. In many cases the OPG can be postponed until after delivery, but if it’s clinically necessary, the radiation dose is extremely low and protective measures can be taken to minimize any exposure.