The short answer
Dental X-rays show what an exam cannot: decay between the teeth, bone loss from gum disease, infection at a root tip, and teeth that have not come in. Read plaque vs. tartar for why bone loss happens. How often you need them depends on your history, your exam, and your risk of decay and gum disease, not a fixed schedule. The dose is very low, and ADA and ACOG consider dental X-rays safe during pregnancy.
General information, not a diagnosis. Your dentist will examine your mouth before recommending treatment.
Why your dentist wants a picture when nothing hurts
Most of what goes wrong in a mouth starts out invisible. A cavity between two back teeth, bone slowly dissolving around a root, an infection at the tip of a tooth that has not started to ache yet: none of these show up in a mirror, and many do not show up to a dentist looking straight at the tooth either.
The ADA describes X-rays as the way dentists diagnose damage and disease that is not visible during a regular exam. They also do the opposite job: confirming that teeth are healthy, and giving a baseline so that a change at the next cleaning and exam can be measured instead of guessed at.
This guide covers the main types, how often they are taken, what the radiation means in plain terms, and what to expect if you are pregnant. If you are new to the practice, the first visit guide explains where X-rays fit into the appointment.
The main types and what each one finds
Each type answers a different question, which is why a dentist chooses them individually rather than taking everything at once.
- Bitewing. You bite on a small tab and the image shows the crowns of the upper and lower back teeth together. The ADA and FDA selection criteria call it the most efficient method for finding decay between the teeth. It is the X-ray most adults get at recall visits.
- Periapical. Shows one or two complete teeth from the crown to the tip of the root and the bone around it. Used for a toothache, a suspected abscess, an injured tooth, or to check the bone around a specific root when gum disease is suspected.
- Panoramic. A machine rotates around your head and captures all the teeth and both jaws in a single image. It is useful for impacted teeth and for new patients with a long dental history, but MedlinePlus notes it is not well suited to detecting cavities unless decay is advanced.
- Full-mouth series. A set of periapical and bitewing images covering every tooth. The selection criteria reserve it for patients with signs of widespread disease or an extensive history of dental treatment.
- Cone-beam CT. A three-dimensional view of the jaws. The ADA's 2024 recommendations say it should be used only when a lower-exposure image will not provide the information needed.
How often you need them
There is no fixed interval, and a dentist who takes the same X-rays on every patient every year is not following the guidance. The ADA and FDA jointly published patient selection criteria that say radiographs should be ordered after a clinical exam and a review of your health history, based on your individual risk of decay and gum disease.
The ADA states it directly: there is no one-size-fits-all interval between dental X-rays. Someone with several recent cavities, dry mouth, or a history of gum disease may need bitewings more often than someone who has gone years without a cavity. Children and teens may need them more often than adults because their teeth and jaws are still developing.
New patients often get X-rays to establish a baseline. If you had X-rays at a previous office, ask them to send the images rather than retaking them. At a dental checkup here, the dentist decides which images are needed after looking at your history and your mouth, and will explain why if you ask.
| Type | What it shows | Commonly used for |
|---|---|---|
| Bitewing | Upper and lower back teeth together; the most efficient view for decay between teeth | Recall visits, at an interval set by your cavity risk |
| Periapical | One or two whole teeth, crown to root tip, with the surrounding bone | A toothache, a suspected abscess, an injured or cracked tooth |
| Panoramic | All teeth and both jaws in one image; not well suited to finding cavities | Impacted teeth, new patients with an extensive history, jaw evaluation |
| Full-mouth series | Periapicals and bitewings covering every tooth | Signs of widespread disease or extensive past dental work |
| Cone-beam CT | A three-dimensional view of the jaws | Only when a lower-exposure image will not answer the question |
Radiation in plain terms
Dental X-rays use a very low dose of radiation. The ADA notes that dental imaging is a minor contribution to the total radiation a person receives from all sources, natural and man-made. The FDA states that the risk of developing cancer from medical imaging radiation is generally very small, and that it rises with larger doses and more exams, which is exactly why unnecessary images are avoided.
Dentists are expected to follow the ALARA principle: as low as reasonably achievable. In practice that means justifying every image, using digital sensors instead of film, and narrowing the beam to the area being imaged. Infinite Dental Wellness uses digital X-rays.
One change surprises patients. In 2024 the ADA's review panel concluded that lead aprons and thyroid collars are not necessary to protect patients and can block the beam, which may mean a retake. It no longer recommends them for any patient, regardless of age or pregnancy. Some offices still use them because of state rules, so do not be alarmed either way.
X-rays during pregnancy
Tell your dentist if you are or might be pregnant. That said, the ADA's pregnancy guidance states that radiographs are considered safe for the pregnant patient at any stage of pregnancy, and the ADA's MouthHealthy site cites the American College of Obstetricians and Gynecologists on the same point.
The usual rules still apply: images are taken only when they will change your care, and the beam is focused on the area being examined. Routine and emergency dental care, including local anesthetic and the treatment of gum disease, is also considered safe during pregnancy. Pregnancy hormones can make gums react more strongly to plaque, so cleanings may matter more during this time, not less.
Questions worth asking
You are allowed to ask why an image is being taken. The FDA suggests these questions for any X-ray exam, and a good answer is short and specific.
- What are you looking for, and how will the result change my treatment?
- Is there an image with lower exposure that would answer the same question?
- Can my previous dentist send recent X-rays instead of retaking them?
- Do you use digital sensors and a narrowed beam?
- Can I get a copy of my X-rays for my records?