Rapid Review on Radiation and CBCT in Dental Practice

Rapid Review on Radiation and CBCT in Dental Practice

Exposure to ionizing radiation and its potential risks are often major concerns of our patients. Ambiguity and confusion exist among the general public, mainly due to the risks discussed in the media and from spurious online information. This leads to confusion, fear, and avoidance by the patient. Therefore, this review aims to attenuate the ambiguity and to provide a clear and evidence-based summary of the current knowledge base for the reader.

As dental professionals, we are aware of the benefits of dental radiography in diagnosis and treatment planning. Therefore, this article aims to arm treatment providers with a thorough understanding of the associated risks and benefits of dental radiography, specifically in regard to an imaging technology that has disrupted dental imaging; 3-dimensional cone beam computed tomography (CBCT).

Written by: Amanda B. Longo and Peter C. Fritz

3D Dental X-rays

3D Dental X-rays

Cone beam computed tomography (CBCT) is a recent advancement in dental imaging and provides a 3D image of the tooth and jaw with high spatial resolution and diagnostic ability.

The dental CBCT does not replace conventional 2D x-rays, but is an additional tool that your dentist or periodontist uses to gain more information, to avoid exploratory surgery, and to perform a ‘virtual surgery’.

A CBCT works by three basic steps: Acquisition, Reconstruction, and Analysis

1. Acquisition
CBCT technology uses the same basic technology of conventional 2D x-rays.  That is an x-ray source sends a beam of x-rays through the object of interest and an x-ray detector collects them on the other side.

As the x-ray beam travels through the object of interest (i.e., our teeth), some x-rays pass through the less dense material and others are absorbed by the dense tissue.

For example; If your tooth has a crack in it, the x-ray beam will be absorbed by the tooth, but will pass right through the empty space of the crack and hit the detector.  This paints a picture on the detector of a solid tooth with an empty space through it.  Voila! Your dentist or periodontist can now confirm a crack in 3D, something they would have missed with the low resolution of a 2D x-ray.

The major difference in the acquisition stage between a 2D and 3D image is the sheer number of ‘pictures’ taken.  With 2D technology, only one photo is captured at a single angle.  With 3D technology, many many photos are captured as the x-ray source and detector move around the patients head.

2. Reconstruction
After all of the individual images are acquired, sophisticated software reconstruct the images to re-create the 3D volume.

Like a Rubik’s cube, the individual images are stacked on top of one another in the sequence they were taken in to build a 3D cube.

3. Analysis and Interpretation
The final stage involves the analysis and interpretation of the images captured.  A great benefit to CBCT technology is the ability to manipulate, maneuver and rotate the 3D volume to scroll through the “stack” of images created.

This drastically improves the ability of your dentist or periodontist to diagnose and plan treatment accordingly.

A question that we are asked all the time is “How much radiation is this going to expose me to?”

This is a highly complex question, with so many factors influencing the answer for each individual patient.  The simple answer is, not more than three dental film x-rays but the information we receive from a single CBCT is exponentially more!

There are many factors and settings in the acquisition stage of the CBCT scan that can be manipulated by the dentist or periodontist to limit the radiation exposure to the patient.  To stay informed, always ask your prescribing dentist or periodontist how they plan to limit you to the lowest possible radiation exposure.

Rapid Review on Radiation and CBCT in Dental Practice

Dental Radiation

Radiation exists in many forms, not all of which are ionizing, the form of radiation that poses a risk to our health.

Low frequency radiation, such as radio waves, thermal/microwaves, infrared, and visible light waves are to low penetrating power to cause changes to the atoms and molecules that make up our body, therefore classifying these types as non-ionizing.

However, higher frequency radiation such as UV, x-ray, and gamma-rays are able to displace electrons from their natural state, and therefore have the capacity to cause cellular damage and pose a risk to human health.

We are constantly and continuously exposed to radiation in the environment (i.e., cosmic sources, radioactive nucleotides) as well as through man-made sources (i.e., medical imaging).

All dental and medical professionals must always weigh the direct benefit and consequences to their patient when prescribing diagnostic imaging (such as chest x-rays, mammograms, CT scans, dental x-rays, etc.). They must ask themselves, “Is the information I will receive from this x-ray worth the size of the risk to my patient?”  They must also ask, “Is there an alternative to this x-ray?”

In the case of dental x-rays.  Most dental professionals can prescribe either 2D dental x-rays or a 3D x-ray, known as a CBCT.

The CBCT allows the clinician to see the teeth and their location in the jaw bone in all 3-dimensions and allows them to map critical structures, to view the quality and quantity of the bone, and to perform a ‘virtual periodontal or endodontic surgery’ without the need for gloves!

In many cases, this amount of information is unnecessary and a single (or multiple) 2D x-rays are sufficient for diagnosis of tooth decay, periodontal disease, or other common dental issues.

Although a dental CBCT does emit more radiation to the patient than a conventional 2D digital x-ray, the amount of radiation is still negligible compared to many other medical imaging devices and other common sources of radiation.

Concerns about radiation exposure and your risk are valid, but you should take every opportunity to speak to your dentist or periodontist about the safety measures and considerations to your personal health when they prescribe an x-ray to help in your dental care.