April 23, 2014

Is interceptive orthodontics a hopeless pipedream?

Is interceptive orthodontics a hopeless pipedream?

In this blog I will address another of the “great unanswered questions” in orthodontics that featured in a previous blog. This is the long-standing issue of whether it is possible to provide interceptive orthodontics and either “cure” orthodontic problems before they develop or make any eventual treatment easier. This process of interception is closely allied to the concept of screening., because if we intend to intercept a disease this needs to be done via screening.

As a result, I would like to start with a short discussion on screening. This is classically carried out to detect disease early and ward off the consequences of a disease by providing treatment when the disease has not done harm or can be treated easily. There is a great summary of screening in “Testing Treatments” by Evans et al. In this book they outline that screening for disease is not as effective as we may hope and suggest that screening should only be done under certain circumstances. I have adapted this for orthodontics.

  1. The condition being screened for is important in terms of public health. Malocclusion certainly affects large numbers of people so this would qualify
  2. There is a recognizable early stage of the condition. Again, we can identify the early development of malocclusion
  3. There is a valid and reliable test for the condition. We know that IOTN can identify malocclusion that requires treatmen
  4. There is a effective and acceptable treatment for the condition so that screening is likely to have an effect on its outcome. This is where we run into problems for orthodontic treatment because can we intercept malocclusion?


Can we intercept malocclusion?

In order to address this question I would like to start with considering our history as orthodontists. Before the advent of the widespread use of fixed appliances, orthodontists used to treat Class I crowding cases by removal of first premolar teeth and allow spontaneous alignment. The advantage of this treatment was that the teeth aligned and may have ultimately been placed in the “zone of stability”. Over the years we have discarded this form of treatment because we were concerned that residual features of malocclusion remained and that the posterior occlusion was not totally corrected. However, it is certainly worth us considering whether this treatment, which aligns the social six, should be explored further and in many ways may be reasonable way forward for our patients who are not so concerned with the attainment of a six key occlusion. But, I hear you say “where is the science behind your statement”? There is none and perhaps we need to investigate this further.

What about discussing scientific evidence?

If I now turn to evidence based practice and address the features of malocclusion that we intercept. The first is the interception of palatally displaced permanent canines. I have covered this in a previous blog post and concluded that there is no evidence that removal of the primary canine can intercept the impaction of a palatally displaced canine.

What about children with increased over jets? Again this is covered in a previous post that reviewed the findings of a Cochrane Systematic review. There is no evidence that early treatment is of benefit, apart from a reduction in the incidence of trauma, but the level of uncertainty about this treatment is still high.

We know that we can correct crossbites “early” and that this treatment is effective.

However, when we consider the statements on screening, we should remember that we are screening to intercept a disorder that affects a large number of people and it is clear to me that the examples that I have given above do not fall into this category. However, I have become very interested in some work carried out by two research teams and I will go into this in more detail.

Orthodontic intervention in the early mixed dentition: A prospective controlled study on the effects of the eruption guidance appliance

This was a really interesting study carried out in Finland. The investigators screened a sample of children in two towns and included 315 children in their study and they started treatment with an eruption guidance appliance for 255 children. These were then compared to a randomly selected sample of children from another town who did not receive treatment.

They showed that interceptive treatment with the appliance resulted in a significant improvement in the occlusion. These findings look encouraging, however, we need to interpret them with some caution. Firstly, this was not a trial, it was a cohort study and there may be biases present between the groups. Secondly, they reported that 33% of the patients who were given the interceptive treatment did not wear the appliance and were excluded from the analysis. The results of this study are, therefore, only applicable to the patients who co-operated and this raises doubts about the overall effectiveness of the treatment. Nevertheless, I still feel that these results are very interesting and while they have not found the solution, this study may provide a direction of future research.


Randomized Clinical Trial of interceptive and comprehensive orthodontics.

This was carried out in Washington State, USA, This was a trial in which patients who were eligible for funded orthodontic treatment were randomly allocated to receive comprehensive treatment or to interceptive treatment, such as space management, strategic extractions, correction of crossbites etc. At follow up, they showed that the patients who had comprehensive treatment had better PAR scores by approx. 4 points, which is just about clinically significant. However, both groups achieved significant reduction in PAR, suggesting that both treatments were effective. They concluded that interceptive treatment provided significant short-term benefits. Importantly, the interceptive treatment is likely to be accompanied by a reduction in costs.

This was a really interesting paper that suggests that interceptive may effective, but it does not result in perfect occlusions. However, we need to consider if all our patients require perfect occlusions and whether some (or many) may be happy to “trade off” a less perfect occlusion for a shorter course of treatment. Perhaps the next step is to develop this concept further and ask our patients what they want?

I have found preparing this post very interesting and I am becoming more convinced that this is one of the “unanswered questions” that should be answered. I think that I will work this up as a study…


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Have your say!

  1. Thanks Kevin. It makes interesting and much useful reading.

    I work in a public hospital where although I am willing to provide treatment with six keys to normal occlusion to all , many are not ready for various reasons including missed school hrs. We do practice some times extraction of premolars to allow crowded teeth to align naturally so called “Driftodontics” followed by short course of fixed appliance.

    Choice of Interceptive treatment as well case selection needs careful consideration, failing which, it may not benefit but prolong treatment duration.

  2. As always Kevin I enjoy your Blog and it’s thought provoking content. I would like to discuss the Keski-Nisula study and other similar studies in more detail. The study involved children commencing treatment at age ~5 using 2 – 3 appliances over a period of 3.3 years. This resulted in an average overjet improvement of only 2.4mm and an overbite reduction of 2mm. There are a number of studies examining the clinical effects of myofunctional appliances such as the eruption guidance appliance and the MRC pre-orthodontic trainer appliances. (Keski-Nisula. Am J Orthod Dentofac Orthop 2008;133:254-60; Methenitou. Journal of Pedodontics 1990;14:219-30; Usumez. Angle Orthodontist 2004;74:605-60; Janson. Am J Orthod Dentofac Orthop 2007;131:717-28). These studies provide somewhat limited clinical evidence as to the compliance and effect of these appliances (but it is all we currently have). A randomised trial of the MRC pre-orthodontic trainer appliance versus a custom made Activator appliance (Idris. Eur J Paediatr Dent. 2012;13:219-24) found the custom made Activator caused less discomfort than the MRC pre-orthodontic trainer appliance and was more acceptable. All four of the previous studies showed that treatment lasted from 13-36 months and protrusion of the top teeth was reduced by only a small amount (1.5-2.5mm). The study of the MRC pre-orthodontic trainer appliance (Usumez) showed it had no ‘growth’ effect and only a dental tipping effect. Another study (Janson) on the eruption guidance appliance followed patients over time and found the 2mm improvement in crowding relapsed to the initial state while the 2mm improvement in bite depth was also unstable and relapsed leaving only 0.5mm of change. Would you then consider this 2mm change in overjet with 1-3 years of treatment to be worthwhile and cost-effective particularly when we have much better evidence for treating overjets of >7mm in similar or shorter time frames?

    • Hi Peter, thanks for the comments. You are way ahead of me on some of this literature! I will have to try and catch up…. You make very good points about cost-effectiveness and this needs factoring into every discussion on interceptive treatment. We need to consider that all methods of interceptive treatment are “additional” procedure to the traditional approach of providing treatment in adolescence. For example in the Class II early treatment studies, several investigators concluded that the costs of treatment were increased with limited benefit. This suggests to me that when we think about interceptive treatment we need to keep it simple.

      Best wishes: Kevin

  3. Indeed, Peter Miles is remarkably well versed in literature. While trying to keep up with treatment timing publications, it occurs to me that rarely (if at all) are the parent’s/patient’s chief complaints mentioned in studies or reviews of articles. Additionally, an accurate assessment of the parent’s/patient’s degree of satisfaction with time and money spent appears to be a sidelined section of investigation. As a “non-researcher” but as a clinician my obligation is to discuss the risks and benefits of treatment timing and to the best of my ability provide evidence based information. Thus, allowing the parties responsible to make an informed decision. Thanks to Kevin and Peter for making that obligation less time consuming.

  4. Kevin your comments relate only to the teeth, as do the other comments. However, early interceptive treatment can enhance the nasal airway by developing the palate – the roof of the mouth is also the same bone that forms the floor of the nasal cavity – and correction of a retruded mandible will enhance the pharyngeal airway. With the increasing awareness of sleep disorders in children, also now associated with mouth breathing and ADHD, shouldn’t we start to look beyond the teeth and begin taking responsibility for these medical conditions which we have it in our power to address.

  5. In this blog post you say

    ” I have covered this in a previous blog post and concluded that there is no evidence that removal of the primary canine can intercept the impaction of a palatally displaced canine.”

    I thought the consensus from the KOB OrthoBlog was that it probably was a benefit depending on timing and canine position – which was the article that said there was no evidence?

    Stephen Murray
    Swords Ortho

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