Medical imaging notice: CBCT uses ionising radiation and should be prescribed only when the expected diagnostic benefit justifies exposure. It is not a routine screening scan and does not replace a clinical examination or specialist radiology report.

What is a dental CBCT scan?

Cone-beam computed tomography, or CBCT, is a three-dimensional X-ray technique. A rotating source and detector acquire multiple projections that software reconstructs into a volume. The dataset can be viewed in axial, coronal, sagittal and curved sections, allowing assessment of teeth and surrounding hard tissues without the superimposition found in two-dimensional radiographs.

CBCT is particularly good for mineralised anatomy. It may show roots, impacted teeth, jawbone, sinus boundaries, the mandibular canal and some calcified pathology. It is not equivalent to hospital medical CT and has limited soft-tissue contrast. Metal restorations can create streaks and other artefacts.

When may CBCT be justified?

A scan may be considered when clinical examination and lower-dose two-dimensional imaging do not provide the information needed for a management decision. Examples include selected implant sites, complex impacted teeth, suspected root fracture, resorption, unusual root-canal anatomy, jaw lesions, trauma and certain orthognathic or surgical plans.

These are possible indications, not automatic reasons. A straightforward implant site or routine root canal may not need CBCT. The prescriber should document the clinical question and explain how the result could change care.

CBCT for dental implants

Three-dimensional imaging can measure ridge dimensions and show relationships to the sinus, nasal floor or inferior alveolar canal. It may support virtual implant planning and surgical guide design. The scan cannot determine bone quality perfectly, guarantee primary stability or compensate for inadequate clinical assessment.

Image acquisition should include the region required for planning and, when relevant, a radiographic guide or reliable digital workflow. Errors in scanning, segmentation, matching or guide support can transfer to surgery, so virtual measurements require clinical safety margins.

CBCT in endodontics

Limited-field CBCT may help in selected cases involving complex anatomy, non-healing treatment, resorption, suspected vertical root fracture or surgical planning. Guidelines describe it as an adjunct rather than a replacement for periapical radiography. Artefacts from posts, crowns and root fillings can obscure the very feature being investigated.

Radiation dose and field of view

CBCT dose varies substantially with machine, field of view, resolution, exposure settings and patient size. It cannot be represented by one universal number. A small field that answers a local question generally exposes less anatomy than a large craniofacial volume. Higher spatial resolution often requires a higher dose.

Optimisation means using the smallest suitable field, appropriate resolution and exposure protocol while still producing diagnostically adequate images. “Low dose” is meaningful only in relation to the actual protocol and task; it does not mean zero risk.

What happens during the scan?

The operator removes removable metal objects, positions the head and asks the patient to remain still while the unit rotates. Acquisition often takes seconds, although positioning and verification take longer. Movement can blur the volume. Pregnancy status, previous relevant imaging and the clinical question should be reviewed before exposure.

Interpretation and incidental findings

The entire acquired volume must be reviewed, not only the tooth or implant site. CBCT can reveal findings in the sinuses, jaws, airway region or cervical structures that need assessment. Interpretation should be performed by someone trained for the volume and scope; referral to an oral and maxillofacial radiologist may be appropriate.

An incidental finding is not automatically disease and can lead to further investigation. This possibility should be included in consent, especially for large fields of view.

Limitations

Uses ionising radiation.
Limited soft-tissue contrast compared with medical CT or MRI.
Metal and motion artefacts can reduce diagnostic value.
Voxel size is not identical to clinical resolution.
Measurements and segmentation require trained interpretation.
A scan may reveal uncertainty rather than a definitive diagnosis.

CBCT versus panoramic and intraoral X-rays

Panoramic and intraoral radiographs remain appropriate first-line tools for many questions. They are two-dimensional and may miss features hidden by superimposition, but typically use less radiation than many CBCT protocols. CBCT should add information likely to affect management, not simply provide a more impressive image.

Children and repeat imaging

Children are more radiosensitive and have a longer lifetime in which radiation effects could develop. Justification and optimisation are therefore especially important. CBCT should not be repeated merely because another clinic cannot access an existing scan. Previous diagnostically adequate images should be requested and reviewed when possible.

Questions to ask before a scan

What precise clinical question will the scan answer?
Would an intraoral or panoramic radiograph be sufficient?
What field of view and protocol will be used?
Who will interpret the complete volume?
Can I receive the DICOM dataset and report?
How will the result change treatment planning?

Preparing for a CBCT appointment

Bring details of recent radiographs or scans and explain the planned treatment, symptoms and relevant medical history. Removable jewellery, glasses, hearing aids and dentures may need to be taken off because metal can create artefacts. Fixed crowns and implants cannot be removed; the operator can sometimes adjust positioning or protocol to reduce their effect.

Most dental CBCT examinations require no injection, fasting or special medication. Contrast agents are not normally used. Patients who cannot remain still because of pain, movement disorder or anxiety should tell the imaging centre in advance so that positioning, support and whether the scan remains appropriate can be considered.

Understanding the report

A useful report links observations to the clinical question and records limitations such as motion, metal artefact or incomplete coverage. Terms such as radiolucency, cortical perforation or mucosal thickening describe appearances rather than a final diagnosis by themselves. The treating dentist should explain which findings affect care and which need monitoring, referral or correlation with another test.

Measurements should be interpreted with the reconstruction orientation and safety margins in mind. The printed screenshot used in a consultation is only a selection from the full volume. Keeping the original DICOM data allows later reformatting and independent review.

Data ownership and transfer

Patients may request the scan and report according to local rules. The transferable record should preferably include the original DICOM series rather than only a PDF or video. When digital implant planning has been performed, related scan, surface-scan and planning files should be identifiable. Secure transfer protects privacy and avoids lossy compression.

Quality assurance

Imaging centres need equipment testing, exposure-protocol review, staff training and procedures for clinical evaluation of image quality. A failed scan should be analysed before any repeat exposure. Audit should track retakes, reasons for referral, field selection and whether reports cover the entire volume. A new machine or higher resolution does not by itself establish better care.

Evidence summary

CBCT is valuable when three-dimensional information is necessary for a defined decision. Safe use depends on individual justification, optimised acquisition, competent interpretation and avoiding routine or duplicate exposure.

Sources

Prepared as general educational information. Imaging must be justified and interpreted by appropriately trained dental professionals.

CBCT Scan