Which is best? Open or closed exposure of palatally impacted canines?
This post is about a new trial that looked at the effects of open or closed exposure of impacted canines. I thought that this was a well-done trial that adds to our knowledge of these two techniques. It was fascinating because the authors looked at this from the point of view of the clinical and patient-reported outcomes. The results certainly translate into our clinical decisions.
The treatment of impacted canines is one of our most challenging treatments. In my clinical experience, it was easy for this treatment to become one long pull on a canine that seemed to last forever. There were also many ways of aligning the canines, and our first decision was always whether we went for an open or closed exposure. This decision was always the surgeons. For some reason, all the surgeons that I worked with preferred an open exposure and bonded chain. This process seemed to work fine, but we did not have any trials that looked at which technique was best.
Since then, Nicola Parkin has done a Cochrane review. She concluded that in 2017 there was insufficient evidence to recommend either technique. She also pointed out that there were three RCTs underway at the time of publication of her review. However, I could not find any other reference to these studies in the review.
I presume that this new paper was one of the studies. A team from Orebro, Sweden, did the trial. The EJO published the article.
Margitha Björksved et al. EJO advanced access: DOI: 10.1093/ejo/cjab015
What did they ask?
They wanted to find out if closed or open exposure was better in terms of
- Treatment duration
- Patient perception of pain and discomfort
- Dental fear
- Treatment complications.
What did they do?
They did a parallel-sided RCT with a 1:1 allocation of the two interventions. The PICO was
Participants: Orthodontic patients with uni or bilateral palatally displaced canines planned for surgical exposure and alignment who were not older than 16 years old.
Intervention: Open exposure of the canine
Comparator: Closed exposure of the canine.
Outcomes: The primary outcome was treatment duration. Secondary outcomes were patients perception of pain and discomfort, dental fear that they measured with a dental fear questionnaire and treatment complications.
Treatment complications included root resorption measured from CBCT images.
They enrolled the participants from January 2014 and February 2017.
They gave the patients and parents information about the trial, and they had a week to decide whether they wanted to take part. The authors used pre-prepared randomisation stratified for the centre. They did an intention to treat analysis. Their sample size calculation was precise.
What did they find?
One hundred seventeen participants completed the trial. 58 were in the open, and 59 were in the closed exposure group.
They found the following:
- The eruption time, measured in months from the exposure until the canine crown was visible, was 8.5 months (SD=5.7) in the open group and 11.5 months (SD=5.7) in the closed group. This was statistically different.
- They looked at the treatment time from the canine being visible to being in position in the arch with good root torque. They found that this was 18.0 months (SD=6.1) in the open and 14.8 months (SD=6.9) in the closed. (p=0.01).
- This meant that the total treatment time was 26.4 months in the open and 26.3 in the closed group. This was not statistically or clinically significant.
- They did not find any other differences for the other outcome measures, apart from pain and discomfort. Their analysis showed that there was statistically more significant pain in the closed than in the open group. Unfortunately, they did not mention if this difference was clinically significant.
Their overall conclusions were:
- The treatments were equally successful. The clinicians aligned all the palatally impacted canines.
- There were no differences in total treatment time
- The closed group reported more pain and discomfort than the open exposure group.
What did I think?
I thought that this was a well done and reported trial. The authors included a large amount of information in the results. I suggest that everyone interested in this subject tries to get hold of a copy of the paper.
The study had a great degree of generalisability as they did it in three centres. It was also great to see outcomes that were associated with our patient’s values. I do not doubt that treatment duration, pain, and harm are more important than ceph and occlusal index measures to our patients.
We need to consider if this paper will influence clinical practice. Firstly, there is no problem with there being no difference in treatment times. This means that the type of exposure may still rest with the surgeon and their preferred technique based on their clinical experience.
However, when we look at pain, it appears that open is best. Unfortunately, I was not too clear on whether the difference was clinically significant. Nevertheless, we can use this information to provide our patients with the necessary information for consent.
Finally, I thought it was great to see a trial done so well and written up so clearly.
Emeritus Professor of Orthodontics, University of Manchester, UK.