CBCT imaging does not meaningfully change decisions on impacted canines?
We all know that CBCT gives us great images of impacted teeth. We can justify this additional radiation dose if the images improve our decisions. However, there is little evidence on whether this is the case. I have posted about this before, and there was a very active discussion on my posts. Several years have passed, and I was interested in this new paper. I wanted to see how the situation has changed (or not).
One of the most logical reasons to take a CBCT image is when we are managing impacted teeth, particularly when there is suspicion of root resorption. However, few “real-world” studies have assessed the value of taking additional CBCT images and exposing a child to an increased radiation dose. This was the focus of this new study.
Peter Stoustrop et al
EJO: Advanced access. DOI: https://doi.org/10.1093/ejo/cjad062
A team from Aarhus, Denmark did this study. The EJO published the paper.
What did they ask?
“What is the impact of cone beam computed tomography on treatment planning for impacted maxillary canines”?
They were also interested in gathering details about the variables that might have contributed to a modification in the treatment strategy and identifying any indicators suggesting the need for an additional CBCT scan.
What did they do?
The team conducted a prospective clinical observational study on the treatment decisions made by 10 orthodontic specialists.
The study had several stages.
- The team identified patients with at least one impacted maxillary canine, and the initial 2D radiographs showed an overlap between the canine and adjacent teeth. In other words, the orthodontists were concerned about root resorption.
- A referring specialist orthodontist initially saw the patient and took 2D radiographs. The orthodontists then referred the patients to Aarhus for the CBCT.
- Before the orthodontist referred the patients, they recorded relevant clinical factors about the canine. These included, for example, whether there was adjacent tooth resorption and the position of the canine. They also prepared their treatment plan based on the 2D imaging.
- A radiologist then reported the CBCT images. The referring orthodontist then viewed the report and the CBCT. The orthodontist then formulated the the final treatment plan.
- They then used the relevant logistic regression analyses to compare the treatment plans and decision changes.
What did they find?
They included 125 impacted canines from 91 patients in the study. These were referred by 10 specialists with experience ranging from 1 to 28 years.
When the new treatment plans were devised. They found a modification in the plan for 34.4% of the canines. The most common alteration involved a change in the direction of orthodontic traction. This was subsequently followed by the extraction of other teeth (12.8%) and the surgical exposure of the canines (10.4%). Notably, in only 3 cases was the plan adjusted from extraction to retention of the canines.
When they examined root resorption, they discovered that 67 teeth were diagnosed with resorption following CBCT, whereas with 2D imaging, this was only 9. However, the analysis did not reveal any impact of CBCT-diagnosed root resorption on the treatment plan.
Finally, when they looked at factors from the 2D images that could identify the best patients for additional CBCT imaging, they found that a significantly larger alpha angle was associated with changes in plans towards removing the canine.
Their most important conclusion was;
“The CBCT images resulted in a change in the treatment plan for approximately one-third of the canines. This was mostly a change in the direction of orthodontic traction. The least frequent change in plan was the decision to remove the canine for only 4 cases.”
Importantly, although the CBCT images provided much additional information, their use did not significantly impact the treatment decisions.
What did I think?
This was a well-done study that looked at a clinically relevant question. Unlike other studies in which orthodontists examined specially prepared case records, this study looked at patients in a “real-world” setting. Importantly, the orthodontists examined the records from their own cases. This adds externality to the study.
We must also remember that these cases were selected because the orthodontists suspected that adjacent teeth were resorbed. The CBCT views were also targeted on the patient’s initial examination. Importantly, these were not CBCT images that had been taken as part of a “routine” set of records.
As a result, the finding that there was only minimal change in the decisions is even more important. This is because if these changes are minimal in targeted patients, it is very unlikely that “routine” CBCT imaging would add any further relevant information. I accept that my view may be controversial. However, we cannot justify exposing young people to increased levels of radiation “in case we find something”.
Emeritus Professor of Orthodontics, University of Manchester, UK.