An occasionally irregular blog about orthodontics

Class III protraction headgear avoids orthognathic surgery: A discussion

By on September 8, 2016 in Clinical Research, Recent posts with 4 Comments
Class III protraction headgear avoids orthognathic surgery: A discussion

Class III protraction headgear avoids orthognathic surgery: A discussion

My last post on Class III protraction headgear reducing the need for orthognathic surgery was read very widely.  Several people have made comments directly and via social media. I feel that these comments were interesting and relevant. I have done an additional post so that I can discuss some of the comments.The main comments were

Was the study ethical?

I am sure that it was. If a trial is to be ethically carried out, the operators in the study need to be in equipoise about the treatment.  That is they do know which is the best treatment.  They then explain this to the patients, as part of fully informed consent.

If the operator is not in equipoise, then they ethically cannot take part in a trial.  

It was clear that when this study started, the operators did not know the best treatment. As a result, the trial was ethical.

How do the patients feel about the results of the trial?

This was a point which was relevant to the patients who were in the untreated control group. Someone suggested that they maybe unhappy because the chance of them needing orthognathic surgery is higher than if they had been treated. 

This is a fundamental issue in all trial. I think that the best way to approach this is to consider that at the start of the study no-one knew that the protraction headgear would be effective. This is why they did the study. Now the results are available practice should change. Therefore, the participants have helped improve treatment for others with their condition.

The converse of this argument is that if the study had shown no benefit, the patients in the treatment group may feel that they had been treated unnecessarily.

The assessment of the need for orthognathic surgery?

download-2I thought that one of the most interesting things about this study was the assessment of the need for orthognathic surgery. A panel of experienced orthodontists made this assessment from the case records.  As a result, this was a method that aimed to capture clinical perceptions.  We know that these are rather nebulous and difficult to measure.

It was also interesting that the panel decisions were not related to the cephalometric measurements.   Some people have raised this as an issue and questioned whether this is a valid approach.  My way of looking at this is to consider that when we make clinical decisions we do not totally rely on cephalometric measurements.  This is where our clinical experience comes into play and we assimilate a large amount of information when we make a decision.  As a result, I think that this method of measuring a complex outcome was an innovative step.  This lends to the strengths of the study.

I feel that the most important fact is that a group of patients were randomised to two interventions and there was a difference in outcome at the end of the treatment.  If the randomisation worked well there was no differences in the groups at the start. As a result, any difference at the end of the study must be due to the protraction headgear.

Myofunctional therapy and breathing

It was no surprise that this post got a few comments on these areas. I have mostly addressed these in other blog posts. While it may be easy to simply dismiss these concepts. I am sure that if I was planning a similar study now, I would include some measurement of airway volume and breathing.

Finally, these comments and discussion have reinforced my feeling that this is an important study and the authors should be congratulated on producing a real landmark paper.

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  1. Birte Melsen says:

    Marida Benedetti and I published a in the World Journal performed on the results of expansion and Delaire mask . The children were 5-9 years of age and 25 years after non of them had surgery. The reason for the correction varied a lot from a posterior rotation of the mandible to a forward growth of the maxilla. The main thing the early treatment seemed to change the tongue posture and the functional pattern . We plan to publish the results as soon as we have seen all the patients . My conclusion early treatment of Class III can be recommended.

    • Shane Curtin says:

      Dr Melsen. I would be most grateful if you could send me the link to that publication that you mentioned. I would realy like to read it. Many thanks, Shane Curtin.

  2. Dear Prof. O’Brien-Thank you for the followup on your recent review of your former student’s recently published study. To your query, ‘Was the study ethical?’, and your own conclusion, ‘I am sure that it was.’ by reason of the fact that the operators in the study had been in ‘equipoise about the treatment’ (i.e., they didn’t know which was the best treatment prior to trial’s onset in 2003.), and also to your further statement, ‘It was clear that when this study started in 2003, the operators did not know the best treatment. ….and as a result, the trial was ethical.’, Dr. O’Brien, as you are well aware, per several historically documented medical atrocities (e.g., the cruel/inhumane medical experiments exposed at the Nuremberg Trials of WW II, the U.S.’ Tuskegee Experiment, etc.), in order to gain ethics committee approval, amongst other factors, a thorough review of pertinent peer-reviewed literature is a mandatory requirement for any trial proposing to request utilizing human subjects. That said, prior to 2003, there were indeed scientifically credible published reports in top-tier journals describing the beneficial morphological effects of reverse pull headgear (RPH) Tx (a.k.a., ‘non-surgical maxillary distraction’) with or without concurrent RPE….e.g., here are just a few: 1.) Angle Orthod. 1996; 66(5):351-62; Changes following the use of protraction headgear for early correction of Class III malocclusion., Chong YH1, Ive JC, Artun; 2.) J. Am J Orthod Dentofacial Orthop 2000;118:55-62; Effective treatment plan for maxillary protraction: Is the bone age useful to determine the treatment plan?; 3.) Am J Orthod Dentofacial Orthop 1998;113:333-43; Skeletal effects of early treatment of Class III malocclusion with maxillary expansion without RPH, Tiziano Baccetti, DDS, PhDa, Jean S. McGill, DDS, MSb, Lorenzo Franchi, DDS, PhDc, James A. McNamara Jr., DDS, PhDd, Isabella Tollaro, MD, DDS). And furthermore, given what Linder-Aronson described in the 1970’s about correlation between posterior naso-pharyngeal constriction in children and increased risk for pediatric OSA (‘Naso-respiratory function and craniofacial growth’: in published proceedings of symposium honoring Professor Robert E. Moyers, February 23 and 24, 1979, in Ann Arbor, Michigan, and several published journal articles), combined with what Bacetti et al (Eur J Orthod, 21 (1999), pp. 275–281; Thin-plate spline analysis of treatment effects of rapid maxillary expansion and face mask therapy in early Class III malocclusionsT Baccetti, L Franchi, JA McNamara),revealed about how RPH-RPE combination Tx increased the nasopharyngeal corridor, I’d think the issue of equipoise possibly be called into question given the reason for the operators’ unawareness (i.e., incomplete review of the literature)…..who knows. But, as you conclude, now that validated published evidence is even more easily accessed/accessible (than in 2003 I’d admit), to withhold RPH and/or RPE Tx for research purposes from a child who might surely otherwise acquire better health outcomes, would not only be deemed unethical, but also be correctly categorized as medically and scientifically indefensible.

    And finally, per you posed question, ‘How do the patients feel about the results of the trial?’, you stated that, ‘Someone suggested that they (untreated control cohort subjects) maybe unhappy because the chance of them needing orthognathic surgery is higher than if they had been treated.’ I was at least one of the clinicians who made that observation (also Dr. Elbe Peter?), and I’m disappointed that, in spite of the (maybe not so easy to readily access) previously published evidence to the contrary, you stated, ‘ no-one knew that the protraction headgear would be effective. This is why they did the study’; but I am encouraged that you concluded, ‘now (that) the results are available practice should change. Therefore, the participants have helped improve treatment for others with their condition. Thanks again for starting this vital conversation Dr. O’Brien

    • Kevin O'Brien says:

      Thanks for your comments. I really do not agree with your view that the evidence was there before the study started. This is because the papers that you quote are retrospective investigations and are really low levels of evidence. This is why we need trials. I am 100% certain that the investigators carried out a review of the literature, but we must appreciate that the level of evidence that is required before a trial is carried out. This is pretty basic scientific method.

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