Rapid canine retraction: Is it actually happening?

Abbas et al did a commendable job in taking upon themselves a huge project involving 2 surgical procedures with a control intertwined in a prospective randomized clinical trial. However, much is desired in the way the results were measured, reported, and interpreted. The article claims that surgical procedures such as corticotomy and piezocision are efficient treatment modalities to accelerate canine retraction, when compared with conventional techniques. We have some concerns regarding the results as they appear in the article.

The mean canine retractions over 12 weeks were reported to be 1.22 mm (±0.08 mm) in the corticotomy group and 0.99 mm (±0.1 mm) in the piezocision group (Table I). In the same time period (3 months), the recorded amounts of molar mesialization were 2.99 mm (±0.55 mm) and 3.0 mm (±0.38 mm) for the surgical groups. This means that the anchorage loss was 3 times the canine retraction! That is, for every 1 to 1.22 mm of canine retraction, the molar came forward by 3 mm. This is very unconventional. Is this acceleration? What is being accelerated, the molar or the canine? The surgeries were performed for the canine; however, the molar ends up getting accelerated. This is perplexing especially when the study concludes that the techniques proposed are efficient methods for accelerating canine retraction.

The authors in the introduction stated that “conventional techniques result in canine retraction rates of 0.5 to 1 mm per month.” Most orthodontists, researchers, and systematic review authors will agree with this statement. Therefore, simple math tells us that in 3 months a canine should be retracted at least 1.5 mm (assuming slow movement) to 3 mm (assuming fast movement). The article, however, reported only 1.22 and 0.99 mm of canine crown retraction by surgically assisted methods, and 0.6 mm by conventional methods (control) over 3 months of continuous force application (150 g). How can this even remotely qualify as “accelerated” tooth movement? The data are not at all supportive of these conclusions. In fact, they are completely out of sync with the orthodontic literature.

Figure 6 shows 1.8° of canine tipping (84.3°−82.5°) as per the reference lines drawn between the long axis of the canine and the palatal plane. A simple visual examination shows that the angular measurements are incorrect. The canine looks way more tipped than just by 1.8°. The angle shown in Figure 6, A , is nowhere close to 84.3°. Such careless mistakes can be avoided.

There is also no mention of how root resorption was evaluated. Was it volumetric analysis or just based on periapical replacement resorption? There is just 1 figure showing some numbers in millimeters. The authors should have given more information.

We think the discrepancies in tooth movement as reported in the article warranted a detailed evaluation, but for some reason it has been overlooked. Complete, accurate, and transparent reporting is an integral part of responsible research conduct. It is important to remember that the correct interpretation and presentation of the data are fundamental in responsible dissemination of information. “Expedited tooth movement” is attracting a lot of attention in the orthodontic community. As soon as an article on those lines appears in a journal, it grabs a lot of attention. The individuals involved in such projects must realize that they are dealing with a very sensitive topic here. The results reported can be repeatedly used in research papers and presentations across the world. The outcomes have the potential to change treatment plans, treatment philosophies, diagnostic decisions, and marketing strategies. This can impact not only orthodontists but also the patient population.

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Apr 4, 2017 | Posted by in Orthodontics | Comments Off on Rapid canine retraction: Is it actually happening?
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