Bitewing X-Ray (Dental): What It Shows, How It Is Taken and How Often

The picture covers the crowns of the upper and lower teeth on one side and just the top of the bone between the roots. It does not show the root tips, which is the job of a periapical. Our guide to the types of dental X-ray lays out how they differ.

Dentists look for four things on a bitewing: decay between neighbouring teeth, decay beneath an old filling, the edges of fillings and crowns, and the height of the bone between teeth, which falls when gum disease is present. Decay between back teeth often starts where the teeth touch, a spot that neither a mirror nor floss can show.

A small sensor or film holder is placed inside your cheek, and you close your teeth gently on a tab attached to it. That is the "bite" in bitewing. The tab holds the sensor still while the machine is positioned outside and fires for a moment. You may be asked to hold still for a few seconds.

Usually one image is taken for each side, and sometimes two per side for a larger mouth, so a full set is often two to four pictures. A lead apron or collar is commonly offered. If you gag easily, tell the dentist so that they can adjust the position or take the image in short steps. Digital sensors, covered in our guide to the RVG dental X-ray, show the image at once.

There is no single interval that suits everyone. People who get cavities often, who have gum disease or who have many fillings may be checked more often than people whose teeth have stayed healthy for years. A child's decay can progress faster in milk teeth, so children can need them sooner than a low-risk adult.

A sensible approach is for the dentist to base repeats on your risk and to tell you what they are looking for. If you are unsure why one is needed, ask. If you have moved dentists, bring earlier X-rays, since a comparison can help avoid repeating them. How decay looks on the picture is covered in our guide to a dental cavity on X-ray.

It is a flat picture of a three-dimensional tooth, so a small cavity on the cheek or tongue side may be hidden behind the tooth. It also does not show root tips or the jaw. For a tooth that hurts, a periapical is usually added, and for wisdom teeth an OPG.

A finding is always checked against an examination. If you are pregnant or think you might be, say so before any X-ray. Treatment for a cavity found this way is explained in our guide to cavities in teeth.