Does using cervical pull headgear improve unerupted canine position?
Cervical pull headgear is used to correct molar relationships. But does it influence the position of unerupted canines? This new paper looked at this clinical question.
The interception of potentially impacted permanent canines is one goal of early orthodontic treatment. The use of the early application of headgear has been looked at in several trials. Unfortunately, these had severe methodological problems and it is difficult to come to clear conclusions. As a result, I was very interested to see this new paper. A team from Norway and Finland did this study. The EJO published it.
Sigurd Hadler-Olsen et al
EJO on line DOI: 10.1093/ejo/cjy013
What did they ask?
They did this study to answer this question:
“Does headgear treatment in young children influence the eruption path of permanent maxillary canines”?
What did they do?
They took data from two randomised trials that looked at the effects of early headgear treatment on seven year old children. In the first study they evaluated the results of headgear treatment on 71 children. The second study was similar and they studied treatment for 67 participants.
The PICO was:
Participants: 7 year old children with Angle Class II malocclusion.
Intervention: Cervical pull headgear with a force of 400-700g worn 8-10 hours per day.
Comparision: No treatment
Outcome: Radiographic position of maxillary canines at the start and end of headgear treatment (when they obtained bilateral class I molars).
They randomised the children into the two groups at the start of treatment. They did not report the details of the trial in this paper. However, I have looked at the original papers and they gave no details of randomisation, sequence generation, concealment or blinding.
When I looked at the current paper, I could not find any information on blinding of data collection.
They carried out an appropriate and detailed statistical analysis.
What did they find?
They provided a large amount of data and I have summarised the main points:
The use of cervical pull headgear resulted in:
- An increase in arch perimeter of 3mm (95% CI 1.13-4.89, p=0.002)
- A more vertical and distal eruption of maxillary permanent canines, but the effect sizes were generally a few degrees and I do not think that they are clinically significant.
- The canine angulation changed more if there was spacing in the arch.
- When there was crowding the HG did not influence canine position.
“Headgear treatment influences the eruption pattern of maxillary canines, especially when there is spacing in the arches”.
What did I think?
Firstly, we need to consider that this is a new analysis of data from two previously published trials. Both trials were very similar and it may be logical to combine the data to increase the power of the studies. However, I decided to look at the original trial reports. The first was published in 2005 and I think that the second was reported in 2004 (but this was not clear). I found several problems. I would like to point out that this reflects the state of development of orthodontic trials over 10 years ago. As I mentioned before, they did not give sufficient details of randomisation, sequence generation, allocation concealment, consent and blinding. When we combine this with the lack of blinding of the recording of data in this paper, this means that the studies are at high risk of bias.
Furthermore, I think that we need to be cautious in the way that we interpret their results. In this respect, the authors are clear. They only measured the radiographic position of unerupted canines. This study was not about a treatment to intercept palatally impacted canines.
Therefore, we can only conclude that early headgear treatment may result in a small change in the eruption patterns of canines. This does not translate into less impactions.
This finding tends to agree with other studies that have looked at the effect of headgear on impacted canines. Unfortunately, these studies have methodological and reporting errors. As a result, we need to be cautious.
My overall feeling is that the current research suggests that there may be an influence of creating space on the eruption pattern of permanent canines. This may be particularly true for the extraction of primary canines. However, before we go fitting headgear to normalise canine position, we certainly need better studies.
I will continue extracting primary canines to attempt to intercept impacted canines.
Emeritus Professor of Orthodontics, University of Manchester, UK.