TADS or surgery to close anterior open bite: The search for evidence?
While working in the clinic, I felt that an anterior open bite was one of the most challenging malocclusions to correct. Nearly all my treatment involved orthognathic surgery. Even then, I thought that the long-term correction was very tenuous! With the advent of TADS, we can obtain intrusion of the upper posterior segments. This then leads to the potential for nonsurgical correction of this complicated malocclusion. However, do we really know the effectiveness of these two very different techniques?
This question was looked at in these two systematic reviews. One is rather old, and the other is relatively recent. I came across these when I looked at the excellent Kieferorthopädie Facebook group.
I have been critical of numerous orthodontic systematic reviews being churned out. However, I thought these were interesting and provided a discussion point on the treatment of AOB. I will briefly look at each of these separately and then discuss their findings.
A team from Seattle did the first review. The AJO-DDO published the paper.
Geoffrey M. Greenlee et al.
Am J Orthod Dentofacial Orthop 2011;139:154-69). doi:10.1016/j.ajodo.2010.10.019
What did they ask?
They did this review to answer this question.
“What is the current state of evidence for the stability of surgical and nonsurgical therapies for AOB malocclusion”.
What did they do?
They followed a standard systematic review methodology. The PICO was
Adequately described interventions for the treatment
Stability of treatment assessed at greater than one-year post treatment.
The exclusion criteria for papers were case reports, editorials/personal opinions, craniofacial syndromes and mixed measures of AOB.
What did they find?
They found a final sample of 21 studies. All studies were case series. Notably, no study included a control group. This meant that they could not get data on standardised mean differences. As a result, they could not carry out a meta-analysis. In general, the quality of the papers was low. This was because of the high dropout rate, lack of consideration of cofounders, no control groups and bias.
At this point, things don’t look so good!
The authors decided to consider the data descriptively. They divided the sample into surgical and nonsurgical groups. No group of patients had posterior intrusion with TADS. Tooth movement was achieved with fixed appliances and extraoral forces when necessary.
They provided a rather complex set of data. However, the most important findings were that after 3 years of follow-up, 75% of the nonsurgical treatment and 82% of the surgical treatments were stable.
Their final conclusions were
“There is no high-level controlled evidence for the treatment of AOB using either surgical or nonsurgical treatment methods”.
Stability with either method is greater than 75%”.
What about the second, more recent paper?
A team from Belem, Brazil, did this study. Progress in orthodontics published the paper.
Daybelis González Espinosa et al
Progress in orthodontics 2020 DOI: https://doi.org/10.1186/s40510-020-00328-2
What did they ask?
They did the study to answer this question:
“What is the stability and improvement for anterior open bite treatment with molar intrusion with skeletal anchorage”?
What did they do?
Again, this team followed a standard systematic review methodology. However, this was a recent paper. As a result, the team reported the review according to PRISMA guidelines. This made it easy to read and interpret.
The team included randomised and non-randomised studies in the review. This immediately lowers the confidence that we can have in the findings. I have discussed this previously.
The PICO was
Adults or adolescent patients who had orthodontic treatment for AOB correction using upper or lower molar intrusion.
Intrusion supported by temporary anchorage devices.
Clinical studies comparing treatment at the start, end of treatment and at least one year into retention.
The stability of AOB. This was done by measuring overbite, lower anterior facial height etc.
The team assessed the quality of the studies using the relevant measure for the case series. Finally, the overall strength of evidence was assessed using the GRADE approach.
What did they find?
After filtering for eligibility, methods and outcomes, the team identified 6 studies for qualitative analysis and 4 for a meta-analysis. None of these studies was an RCT.
There were many differences between the clinical techniques used for intrusion and retention. This meant that there was a high degree of heterogeneity in the findings.
They presented a large amount of data from the meta-analysis of the four studies. I thought that the most important findings were
The mean relapse of overbite was 1.23 mm. Molar intrusion showed a relapse rate of around 12% for the maxilla and 27% for the mandibular molars.
Their overall conclusion was
“The stability of AOB through intrusion and TADS can be considered similar to that reported in surgical approaches to this treatment.”
“More research is needed”!
The overall level of evidence was low.
What did I think?
Firstly, I cannot help thinking that the evidence for correcting AOB is weak. This is because the studies are at the case series or retrospective investigations level. These reviews illustrate the problem of looking for evidence for complex orthodontic treatment.
In an ideal world, we may have information from a clinical trial. However, running a trial into AOB treatment is fraught with problems. Firstly, the prevalence of AOB is relatively low, meaning it would be challenging to recruit a large sample for randomisation.
The next issue is with randomisation. As part of the ethics of a trial, an operator is supposed to explain to the participant that they do not know the best treatment for their condition. They then need to explain the options. For a trial of TADS against surgery, this is clear. In lay people’s terms, the competing interventions are
! Screwing a small attachment into your jawbone or
2 Giving you a general anaesthetic, detaching your upper jaw from your heading, taking some bone away and putting you back together!
I imagine most patients would say,
“If you don’t know which is best, I would rather have the screws in my jaw”?
So, a trial is not possible or unlikely to succeed. Another approach is a cohort. One of these is being done by the Seattle team, and the results will be exciting. However, it may be a while until we get these results.
So, what do we do?
In effect, our evidence is weak. So I would discuss the two options and explain to my patients that we do not know the best treatment. But the TADS are the least invasive, and perhaps this is the way to go, instead of surgery.
I realise that there are case reports about clear aligners treating AOB. In addition, to myofunctional techniques and all the other fringe methods. However, the level of evidence for these techniques is even lower than we have discussed.
As a result, we need to be cautious and use the least invasive method until we get better evidence from ongoing studies. So, it would be TADS for me!
Emeritus Professor of Orthodontics, University of Manchester, UK.