Cone beam computed tomography (CBCT) is a type of dental X-ray that produces a three-dimensional (3D) image of the teeth, jaws and surrounding bone. This article explains how CBCT works, how it compares with standard dental X-rays, what it is used for, and the risks and limits to be aware of.

How CBCT works

During a CBCT scan, a cone-shaped X-ray beam rotates around the head, usually in less than a minute, taking many images from different angles. A computer combines them into a 3D model that can be rotated, enlarged and viewed in thin slices. This shows the position of teeth, roots, bone, nerves and sinuses in a way a flat image cannot.

CBCT compared with standard dental X-rays

Standard dental X-rays are two-dimensional (2D). They include small intraoral X-rays (bitewings and periapicals), which show a few teeth in detail, and panoramic X-rays (OPGs), which show both jaws in one image. They remain the usual first choice for finding decay, checking gum and bone levels and routine monitoring.

Because 2D images flatten everything into one plane, structures can overlap, and distances and the true position of a tooth or nerve can be hard to judge. CBCT avoids this, which is why it is used when the extra detail will change the diagnosis or plan.

	Standard 2D X-rays	CBCT
Image	Flat, single view	3D, viewable from any angle
Typical use	Decay, gum and bone checks, routine monitoring	Implant planning, impacted teeth, complex root canals, some jaw problems
Radiation	Lower	Higher than 2D X-rays; usually lower than a medical CT scan
Availability	Most dental practices	Some practices and radiology clinics

What CBCT is used for

Dental implants

CBCT shows the height, width and shape of the jawbone where an implant may go, and the position of nerves and sinuses. This helps choose the implant size and position and shows whether bone grafting may be needed. The scan can also be used to design a surgical guide that helps place the implant as planned.

Root canal treatment

Some teeth have extra or curved canals, cracks or infections that do not show clearly on a 2D X-ray. A small-area CBCT can help find these, and can help assess a tooth that is still causing symptoms after treatment.

Wisdom teeth and oral surgery

When a lower wisdom tooth sits close to the nerve on a standard X-ray, CBCT can show how close it really is. It is also used to locate impacted teeth, cysts and other changes in the jaw before surgery.

Orthodontics

CBCT can show the position of unerupted or impacted teeth, root angles and the relationship between the jaws, which can help plan more complex orthodontic treatment or jaw surgery. It is not needed for most routine orthodontic cases.

Gum and bone problems

In some cases of gum disease, CBCT can show the shape of bone loss around teeth more clearly than 2D images, and help plan surgical treatment.

Risks and limits

Radiation

CBCT uses ionising radiation. Doses vary widely with the machine, the size of the area scanned and the settings. A CBCT scan generally gives more radiation than a small intraoral or panoramic X-ray, and usually less than a conventional medical CT scan of the head. The risk from a single scan is small, but radiation adds up over a lifetime, and children are more sensitive to it.

For this reason, CBCT should only be used when it is likely to change the diagnosis or treatment, following the ALARA principle (as low as reasonably achievable). Using the smallest area and lowest settings that answer the clinical question keeps the dose down. If you are or may be pregnant, tell the dentist before any X-ray.

Image limits and interpretation

Movement during the scan, and metal fillings, crowns or implants, can create streaks or blurring (artefacts) that hide detail. CBCT shows hard tissues well but soft tissues poorly. Scans can also reveal incidental findings outside the teeth, so the whole image needs to be reviewed by someone trained to read it, and findings checked against a clinical examination.

Cost and availability

CBCT machines are expensive and not every practice has one. You may be referred to a radiology clinic for the scan.

Safety rules in Australia

Dental X-ray equipment, including CBCT, is licensed and regulated by state and territory radiation safety authorities, with national guidance from ARPANSA (the Australian Radiation Protection and Nuclear Safety Agency). Requirements cover equipment testing, operator licensing and keeping doses as low as reasonably achievable. Staff stay behind shielding or outside the room during scans.

Developments to watch

Newer machines offer lower-dose settings and smaller scan areas. Software, including artificial intelligence tools, is being developed to help identify problems on scans, although results still need checking by a clinician.

Common questions

Does a CBCT scan hurt?

No. You sit or stand still while the machine rotates around your head. Metal items such as earrings, glasses and removable dental appliances are usually taken off first.

Will I need a CBCT scan?

Most people never need one. It is usually reserved for implant planning, impacted teeth, complex root canals or other cases where 2D X-rays do not give enough information.