Understanding Dental X-Rays

Why images are needed at all

A visual examination can only assess surfaces the dentist can see and reach. The areas where adjacent teeth touch, the inside of a tooth, the tips of the roots and the level of the supporting bone are all invisible to direct inspection. Radiographs make those regions assessable.

This is why a dentist may say a tooth looks fine but they would still like an image: the two answer different questions.

The common types

Different images are taken for different purposes.

• Bitewings — show the crowns of upper and lower back teeth together; used mainly to detect decay between teeth and to check bone levels
• Periapical — shows one or two teeth from crown to root tip; used when investigating a specific tooth, its nerve or the bone around its root
• Panoramic — a single broad image of both jaws, the sinuses and the joints; useful for an overview, wisdom teeth or planning, but too low in detail to reliably diagnose small cavities
• Cone beam CT — a three-dimensional scan used selectively, most often for implant planning or complex assessment

Radiation and safety

Dental radiographs use low doses, and digital sensors have reduced them further compared with film. Protective measures, tight collimation and taking images only when clinically indicated all limit exposure.

The guiding principle across dentistry is that images are justified case by case rather than taken on a fixed schedule out of habit. If you are pregnant, or unsure why an image is being proposed, say so — the reason should be explainable in a sentence.

Asking to see your own images

Radiographs are among the most useful teaching tools in dentistry. Asking your dentist to point out what they are seeing — the dark shadow between two teeth, the height of the bone crest, an existing filling and where it ends — tends to make the rest of a treatment discussion far easier to follow.

You are also entitled to request copies of your images if you move practices or seek a second opinion.