October 14, 2019

How do we treat anterior open bite? A real world study.

One of the most challenging problems that we treat is anterior open bite.  This ambitious new study was carried out in the real world of orthodontic practice.  I thought that it gave us great information.  Everyone should read this paper.

 Anterior open bite is one of the most challenging problems that we treat. This is because there is a dearth of scientific evidence on the best method of treatment. Furthermore, any treatment that simply extrudes the incisors, to close down the AOB is particularly prone to relapse.  As a result, we use a wide variety of techniques. These tend to be fixed appliance treatment only, orthognathic surgery, aligners, and temporary anchorage devices.  However, we do not the factors that may influence our treatment decisions.  The AJO published this new ambitious study. A team led by academics at the University of Washington, USA did this research.

What did they ask?

They did this study to answer this question.

“What practitioner and patient characteristics influence treatment recommendations for adults with anterior open bite”?

What did they do?

This was a very complex and ambitious study.  They did the study as part of the National Dental Practice-Based Research Network.  This is a network of dental practitioners who carry out practice-based research.  Their short mission is

“To improve oral health by conducting dental practice-based research”.

In effect, they do investigations in the “real world” of dental practice. There is no doubt that this is the way forward for dental research. Currently, most orthodontic research is carried out in dental schools. It is, therefore, doubtful that this is totally transferable to the private practice setting.  As a result, the findings of these studies are going to be very relevant.  This orthodontic team worked with the national study to do this investigation on the treatment of anterior open bite.

The team recruited providers of orthodontic treatment from six regions of the USA. They then collected data on the practitioners and their patients who were having therapy for AOB.

The patients were adults who had an Anterior open bite.  The practitioners provided information from their clinical exam, cephalogram and intraoral images.  They sent this information to the regional centres for analysis.

They collected the following data on the practitioners

  • Gender
  • Race
  • Ethnicity
  • Years in practice
  • Nature of practice

This information was gathered about the patients

  • Their age and gender
  • Dentofacial characteristics
  • ANB, mandibular plane angle, incisor angulation, facial height, overbite and overjet.


They divided the treatment decisions into

  1. Aligners
  2. Fixed appliances
  3. Temporary Anchorage Devices
  4. Orthognathic surgery

The study team also developed an AOB index (POSI) that recorded the degree of the open bite from the intraoral photographs.

Finally, they did a sophisticated statistical analysis. They did this in several stages,  The final step involved identifying any predictors of the treatment decisions.

What did they find?

They found a large amount of clinically useful information. I do not have enough space to cover all the information here. Consequently, I am going to concentrate on the predictors of the treatment.

They obtained data from 91 practitioners, and most of these were orthodontists.  They obtained usable data from 347 patients. More than 60% of these patients fell into the most severe grades of POSI.

345 patients were recommended 1 of the 4 main treatments.  These were

Fixed appliances only14642%

When they looked at the predictive models


White and Asian patients were advised Aligners almost 3 times as often as black or Hispanic/Latino patients.  Patients with tongue posture habits were 2.4 times more likely to be offered aligners over fixed appliances.


Practitioners from private practices were much less likely to offer TAD treatment than practitioners in an academic setting.


When they looked at predictors for surgery versus any other type of treatment, these were the race of the patient, whether they had insurance coverage, the presence of posterior crossbite, molar discrepancies, size of AOB and increased mandibular plane angle.

What did I think?

This was an extensive and ambitious investigation that provided a great deal of clinical information.  As a result, the well-written paper was lengthy and very detailed. I hope that I have provided sufficient information on this work, but I suggest that you read the full article, if you can get access.

I thought that the findings were fascinating.  The investigators have written a clear discussion that raised many important points. Again, I shall not go into all aspects of this. However, I thought that it was interesting that the orthodontists did most of the treatments using fixed appliances or surgery.  Currently, there is a large amount of interest in the use of TADS and Aligners for AOB. Paradoxically, this interest was not reflected in the findings of this study. This may suggest that there is a time lag for the adoption of these relatively new techniques. Alternatively, they may also not be as popular as some of their proponents would have us believe?

When I looked at the data for surgery vs all the other treatments. I felt that some of the findings, for example, the effect of the skeletal discrepancy on the treatment decision were self-evident. Nevertheless, the influence of insurance coverage on this decision was clearly significant. This means that the treatment decision was influenced by economic factors. As a result, I wonder if we could suggest that the “best treatment” was potentially being denied to patients who would have benefited had they got insurance coverage.  But I will concede that this may be the European Socialist in me!

Final comment

Finally, it was great to see research done in a practice setting. I look forward to seeing the results of the treatment that they carried out. I hope that there are sufficient numbers of similar cases treated by different methods. It could then be possible to make some comparisons on the effectiveness of the different treatments. While this would not provide us with the level of evidence that we may get from a trial. It could be a great way forward for orthodontic research.

If I were starting my research career again, I would be working with these practice-based networks to do research of real value. This is the next step and challenge for orthodontic researchers.

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Have your say!

  1. Dear Prof O’Brien

    I agree that this was a very carefully constructed and ambitious project.

    I just finished a cursory reading of the paper and it seems that there is at least one area of importance that I think might have been more extensively reported upon, and that is, precisely WHY, despite its low prevalence of about 17% (of pts. w/pre-Tx skeletal discrepancies), do adults w/Dx: AOB actually seek treatment in the first place; that is, despite what is mentioned in the ‘Methods’ section of the abstract (‘….Patients were asked about their demographic characteristics, previous orthodontic treatment, and GOALS FOR TREATMENT.’) wasn’t there mention/showing of data elsewhere in the paper about the patients’ stated objectives for seeking Tx of their AOB’s?

    Maybe something was overlooked here, but it leaves this reader anyway to infer that the primary reason for most (all?) of these adults having sought out Tx for AOB closure, was that they were maybe mostly concerned about perceived negative esthetics…..not sure, I could be wrong. But if I am even partially right here Dr..O’Brien, that would seem to imply that possibly the co-morbid skeletal traits mentioned in this paperas being often associated with pre-/post-AOB Tx, specifically, ‘transverse or A-P discrepancies, larger open bites, and steeper mandibular plane angles’, all of which are often comorbities of naso-respiratory incompetence, low tongue posture, etc. from pre-adulthood years, was not of significant importance to either the patient and/or treating (mostly orthodontist) clinicians.

    I certainly hope that I am incorrect here.

    Kevin Boyd

    • Seems that this article was not about etiology as it gave one sentence to the topic:

      “The etiology of anterior open bite may be straightforward, such as a digit habit, or multifactorial, related to skeletal, respiratory, and neuromuscular factors.3,4”

      Thats it…..from what I read, nothing is mentioned in the article about addressing any of these factors.

      Its “all about the mouse trap”, and is not concerned with “how the mice got in the house to begin with” nor “how to keep them out and avoid having mouse traps!”

  2. Kevin,
    Your topic today is a perfect opportunity to mention the AAO Winter Conference in Austin , Texas, Feb. 7-9, 2020. The topic is, All About Openbites, Diagnosis and Treatment Options for Today’s Orthodontist. Drs. Greg Huang and Jim Vaden have put together an impression group of speakers who will address these most difficult and least stable orthodontic cases. Dr. Huang is also planning to release the much awaited results of the PBRN Open Bite study. Registration is now open. More information can be found at AAOinfo.org or [email protected]

  3. FYI ,yes the “best tmnt.is denied to some pts due to finanacial coverage”.Even as a “European Socialist “sic (did not know that socialism was geographically based ,LOL) you well know that financial issues always are a major factor .
    Hence massive wait lists for NHS ortho.in the UK.
    In my area of Canada ,we are blessed with orthognathic surgery covered by medicare (at an insultingly low fee ,as usual ).We are also blessed with very ,very high quality OMFS surgeons with no wait lists of any consequence.
    I would ,in this circumstance be veering towards surgical options as I prefer not to be involved in retreatments.
    Lots of potential,that I see ,in aligners in these open bite cases.
    Great new research body ,by the way.

  4. This is an interesting study. It’s interesting partly because removable (aka biomimetic) devices were not mentioned. In 2006 we presented at the European Orthodontic Society meeting, showing how we closed AOBs in kids. Later, we published similar findings in adults (1). The point is that AOB is not a single condition (a bit Class III malocclusion in that respect). I consider that there are 4 sub-types of apertognathia, which I won’t describe here for the sake of brevity. It’s also interesting since “race” seems to be a indicator of treatment choice. The human genome has been sequenced – there is only one human race. I think the word the authors are likely missing is (cranial base) phenotype. What race is someone who has white and black parents? It doesn’t matter – what does matter is the clinical phenotype (Mr Obama is a good example). Moreover, the ‘secret sauce’ is in the post-treatment maintenance of the correction. Any data on how these cases fared in the long-term?

    1. Harris WG, Singh GD. Resolution of ‘gummy smile’ and anterior open bite using the DNA appliance. J Amer Orthod. Soc. 13(4):30-34, 2013.

    • ….but Dave, are you also unconcerned about lack of discussion about how and why AOB’s exist, resist TX, relapse and persist?


  5. Thank god for insurance! I can get my money faster and put patients at risk with surgery! Let’s see the long term results 5-10 years post surgical. Funny thing about musculature and habits how they come back to haunt us. And what about quality of life pre and post op perceived by patients.

    • “At risk is minimal (very )IF you have surgeons doing 2or 3 cases a week ie.are proficient and efficient but I accept your point.The long term retention studies have been done long ago!
      They were ,however ,generally and as usual ,carried out by orthodontists.
      Long term retention studies do not seem to be the surgeons forte !LOL

  6. Thanks for the article. This type of research is truly of significant value. Participation from clinicians is a vital part of this research. The U.S. networks for Practice Based Dental Research have done several meaningful projects, and will likely be doing more research projects like this in the near future, including a class II study, and one on root resorption. We welcome practitioners in the United States to plan on participating in these studies. More information will be forthcoming as these projects move forward.

    -Jeff Erickson, member of the AAO committee on Practice Based Research

  7. Harvold had his Monkeys, We”ve got our Sapiens in our offices, or soon to be.
    The answer is ‘blowin in the wind’ that ain’t goin in their noses.

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