A panoramic film shows both jaws in one frame; a periapical film shows a few teeth in detail. Here is when each one is taken and what each one can miss.
A panoramic radiograph captures both jaws, the jaw joints and the floor of the sinus in a single image. A periapical radiograph shows two or three teeth together with their root tips and the surrounding bone. One is a map, the other is a close up of a single street on that map, which is why they rarely replace each other.
What a panoramic film answers
It is the film of choice for impacted wisdom teeth, cysts and other larger lesions, suspected fractures, jaw joint areas, unerupted teeth in children and the general bone height before implant planning. The machine rotates slowly around your head, the exposure takes about twenty seconds, and nothing is placed inside the mouth.
What a periapical film answers
Inflammation at the root tip, the length and density of a root canal filling, a suspected root fracture and decay hidden under an old filling all show up here. During root canal treatment this film is used to check working length and to document the result afterwards. Resolution is higher because the sensor sits directly behind the tooth.
The practical differences
- Coverage: both jaws versus a few teeth
- Detail: fine root outlines and small cavities read better on a periapical
- Sensor position: outside the mouth versus inside it
- Purpose: screening and surgical planning versus following one tooth
- Overlap: the front region of a panoramic film is often obscured by spine and opposing jaw shadows
Why both are sometimes taken
When the source of pain is unclear, the dentist starts wide and then narrows down. Gum disease is assessed differently again, with a series of small films that show bone levels around each tooth, and that series usually guides periodontal treatment planning.
About radiation and image quality
Dental exposures are low, and digital sensors need less radiation than film did. Even so, every image should have a reason behind it, and you are entitled to ask what a film will change in your plan. Tell your dentist if you are pregnant. Positioning matters too: movement blurs a panoramic image, and a sensor that is not parallel to the tooth makes roots look longer or shorter than they are, which can mislead measurements.
Bringing your old films
A shadow at the tip of a root means one thing if it appeared this year and something quite different if it has been the same size for a decade. Only a comparison can tell you which. If you have previous radiographs, bring the digital files and note the dates they were taken. It often saves a repeat exposure and it always makes the interpretation more reliable.
