Short answer: Dental tomography (volumetric tomography or cone beam computed tomography) is an imaging method that shows the teeth, jawbones and surrounding structures in three dimensions. It is used in situations such as implant planning, impacted teeth, complex root canal treatments, and the assessment of cysts and trauma. Its radiation dose is higher than that of a panoramic X-ray but generally much lower than that of a medical CT scan, and it is taken only when necessary.
In dentistry, imaging is the basic way to assess structures that cannot be seen during an examination. For many years, two-dimensional X-rays met this need; however, some treatments require a third dimension to see the width of the bone, the position of a nerve or a crack in a root. Dental tomography is the method that answers exactly this need. In this article we look at what it is, how it differs from a panoramic X-ray, when it is requested and how safe it is in terms of radiation.
What is dental tomography?
Dental tomography is an X-ray method that images the teeth, jawbones, sinuses and surrounding anatomical structures in three dimensions. In the medical literature it is called cone beam computed tomography (CBCT), while in Türkiye it is commonly referred to as volumetric tomography or dental CT.
The device makes a single rotation around the patient's head and takes hundreds of images with a cone-shaped beam. A computer combines these images to create a three-dimensional model. On this model, the dentist can examine any area from different angles, slice by slice, and measure the height and width of the bone and the distances between structures.
Depending on the need, the area to be imaged can be a small region (for example, around a single tooth) or a large area covering both jaws. The smaller the field of view, the higher the resolution and the lower the radiation dose.
How does it differ from a panoramic X-ray?
The basic difference between dental tomography and a panoramic X-ray is dimension: a panoramic X-ray shows all the teeth and jaws in a single two-dimensional image, while tomography presents the same area in three dimensions and in cross-sections.
- Panoramic X-ray: Used to get a quick overview of the mouth. It gives general information about cavities, missing and impacted teeth, bone loss and roots. However, because structures overlap, some details can be hidden, and magnification and distortion can vary from region to region. It does not show the width, or "thickness", of the bone.
- Dental tomography: Shows structures separately and close to their real dimensions. The distance from a nerve to a root, the width of the bone or the real size of a lesion can be clearly assessed.
These two methods are not rivals but complement each other. For most patients a panoramic X-ray is sufficient; tomography is requested to answer specific questions. The dentist decides which image is needed, taking into account the examination findings and the planned treatment; in some cases a panoramic X-ray is taken first, and then a small-field tomography is requested only for the suspicious area. This step-by-step approach helps avoid unnecessary radiation exposure.
Dental tomography should also be distinguished from the medical computed tomography used in hospitals. Medical CT was developed for every part of the body and for soft tissues; dental tomography focuses on tooth and bone structures and is usually taken with a much lower dose.
Which treatments require it?
Dental tomography is requested when two-dimensional X-rays do not provide enough information and a three-dimensional assessment would change the treatment decision. Its main uses are:
Implant planning
Before an implant, the height, width and density of the bone, the floor of the sinus and the position of the jaw nerve are assessed with tomography. This information is used to plan the size and angle of the implant and, if necessary, to determine whether a bone graft or sinus lift is needed.
Impacted teeth
When the roots of the lower wisdom teeth appear close to the jaw nerve on a panoramic X-ray, their relationship is clarified with tomography. The position of impacted canine teeth and their effect on the roots of neighboring teeth are also assessed with this method; this information is important for orthodontic treatment planning.
Root canal treatment
Small-field tomography can be helpful when investigating complex root structures, additional canals, root fractures, the real size of inflammation at the root tip or the cause of a failed root canal treatment.
Cysts, tumors and trauma
It is used to assess the borders of lesions in the jawbone and their relationship with neighboring structures, as well as fractures in facial and jaw trauma.
Orthodontics and the jaw joint
It is not requested routinely in orthodontics; however, it can be used in selected situations such as impacted teeth, marked jaw asymmetries, cases where surgery is planned or the assessment of the bone structure of the jaw joint.
What should you know about radiation and safety?
The radiation dose of dental tomography is higher than that of a panoramic X-ray but generally much lower than that of a medical CT scan. The dose varies depending on the type of device, the size of the field of view and the resolution settings. Small-field scans involve a much lower dose than large-field scans.
The basic principle in radiology is "as low as reasonably achievable". In line with this principle:
- Tomography is requested only if it will make a real contribution to diagnosis or treatment planning; it is not taken for routine screening.
- The field of view is limited to the area that needs to be examined.
- In children, the need for it is assessed with particular care because they are more sensitive to radiation.
- Where appropriate, a protective thyroid collar can be used.
If you are or might be pregnant, you must report this before the scan. During pregnancy, dental tomography is considered only in situations that cannot be postponed and that directly affect treatment. If you have had tomography scans before, it is helpful to share them with your dentist to avoid unnecessary repetition.
How does the scan work?
A dental tomography scan is a short procedure that requires no needles or medication and no preparation. The process usually goes as follows:
- Preparation: Metal items such as earrings, necklaces, glasses, hair clips, removable dentures and piercings are removed; they can cause interference in the image.
- Positioning: Depending on the type of device, you stand or sit and rest your chin on the chin support. Supports are used to keep the head still.
- Scan: The device rotates around the head. The imaging time is usually between a few seconds and half a minute. Not moving and not swallowing during this time is important for a clear image.
- Assessment: The three-dimensional images obtained are examined on a computer, and the dentist shares the findings with you.
People with claustrophobia need not worry; most dental tomography devices are open and the patient does not enter a tunnel. You can return to your daily life immediately after the scan.
What does the tomography reveal?
Tomography makes the treatment plan more predictable. For example, these images make it clear whether there is enough bone for an implant, how close to the nerve the work will be during a wisdom tooth extraction, or what is causing the problem in a tooth that has had root canal treatment. This allows the dentist to explain the options and possible risks to you with more concrete data. For other questions about imaging and treatment processes, you can visit our frequently asked questions page.
When should you seek imaging in Ankara?
In situations such as an implant, the extraction of an impacted tooth, recurring root canal problems or a swelling noticed in the jaw, your dentist may recommend a three-dimensional assessment; which image is needed is decided together after the examination. At our polyclinic in Park Oran Ofis, Çankaya, we plan the necessary imaging based on the examination findings and review the results with you in detail. To make an appointment, you can visit our contact page.
Frequently asked questions
Is dental tomography harmful?
Dental tomography involves radiation; however, its dose is generally much lower than that of a medical CT scan. When it is taken only when necessary and with the field of view limited to what is needed, the information it provides outweighs the possible risk.
What is the difference between dental tomography and a panoramic X-ray?
A panoramic X-ray shows all the teeth and jaws in a single two-dimensional image. Dental tomography presents the same area in three dimensions and in cross-sections, making it possible to see details such as the width of the bone and the position of the nerve.
How long does a dental tomography scan take?
The imaging time is usually between a few seconds and half a minute. The whole procedure, including positioning, is usually completed in a few minutes.
Is tomography required for an implant?
In implant planning, the height and width of the bone and its distance from structures such as the nerve and the sinus are assessed with tomography. For this reason, tomography is recommended in most implant cases; the dentist decides whether it is necessary.
