An occasionally irregular blog about orthodontics

Over 200 million injuries to incisors caused by increased overjets: What can orthodontics do?

Over 200 million injuries to incisors caused by increased overjets: What can orthodontics do?

Over 200 million injuries to anterior teeth caused by increased overjet!

Today I came across this interestingly titled paper via the Dental Elf Twitter feed.  This paper is an interesting systematic review and meta-analysis of the literature concerned with Traumatic Dental Injuries (TDI) and increased overjet.

Unknown-3Over two hundred million injuries to anterior teeth attributable to large overjet:a meta-analysis

Stefano Petti  Dental Traumatology2015; 31: 1–8;

doi: 10.1111/edt.12126


Dr Petti aimed to analyse the association between overjet and TDI and provide a picture of the problem on a global level.  He searched the literature from 1990-2014. The search included cross-sectional or case-control studies.  They also considered important variables such as overjet and lip competence.  This was a very thorough and detailed review.  The main outcome measure was the odds ratio for traumatic dental injury due to large overjet.

What did he find?

After an extensive search and filter of papers he included 54 eligible studies.  This enabled him to carry out a comprehensive meta-analysis and present a large amount of data.  I have reproduced the most important table below.

Type of teethOverjet ThresholdPooled Odds Ratio95% Confidence intervals

He also calculated that the number of TDIs attributable to a large overjet worldwide was 235,008,000!

What does this all mean?

This paper was extensive and necessarily complex.  But, it was a bit tricky to read and understand.  I will concentrate on the data in the table above.

If we start by explaining odds ratios.  I have done this in a post that can be found here.  But, I will go through this concept again.

The odds ratio (OR) is the association between an exposure (increased OJ) and outcome (trauma).  Dr Petti found that  the Odds Ratio was greater than 1 meaning that an increased overjet was with a higher odds of trauma.  As the  OR for both OJ thresholds of 3-4mm and 6mm was 2.01 and 2.24 respectively,  this meant that there is twice the odds of trauma if an overjet was greater than 3-4mm.. He concluded that this was a substantial risk and that dentists/orthodontists could provide preventative methods, for example, mouthguards, counselling on risk and orthodontic treatment  for a child with an increased overjet.

Easier said than done! What does this mean for orthodontics?

I felt that this was a very interesting paper that highlighted an important issue for the long-term dental health of children.  While I accept that the odds of me being confused appear to increase with my age, I was a little confused with this paper.  This was because it appeared to me that if a young persons overjet was greater than 3-4mm, then the chance of trauma increased by a factor of 2.  But,in my orthodontic world an overjet of this size is not markedly increased, as most of my treated Class II patients end up with an overjet this size following relapse. However, my world may not be same as that of other orthodontists….

images-25When I thought about the potential role of orthodontic treatment in reducing the chance of trauma it was clear to me that I needed to consider treatment timing.  The Early treatment Class II RCTs, revealed that a high proportion of traumatic injuries had occurred before “early treatment” had started. This makes me wonder whether we should start treatment as soon as the upper incisors erupt?

I feel that it is also important to evaluate the effects of early treatment in preventing trauma. I have previously reviewed this in this post.  This showed that we needed to treat ten patients to avoid one episode of trauma.  It is for you to decide whether this is an effective “interceptive” treatment. I am not so sure.

We could consider giving our patients mouthguards as soon as the incisors erupt, but these probably only work for contact sports and do not prevent the playground accident.

What have I got from this paper?

This is another paper which shows that children with an increased overjet have an increased chance of trauma. It, therefore, provides us with useful information.  But, it also raises many questions on the role of  orthodontic treatment in potentially preventing trauma.  Perhaps, I should consider what I would do when a 6-year-old child with a 8mm attends my clinic?.  I would explain to them, and their parents, that they are at risk of trauma. We would also make an individual risk assessment based on their activity particularly with sports (but at this age they are unlikely to be playing contact sports?). We can then come to a joint decision on management.  But this does not answer the question on whether we should correct prominent teeth as soon as  the incisors erupt?  We could do this easily with a functional, 2 X $ appliance or a simple old-fashioned removable appliance.  If we are to do this, we need to consider the following

  • the burden of care
  • can the patients parents or healthcare system afford it?
  • how do we retain the correction and for how long?
  • how effective is the treatment?

This looks like a trial for someone who wants to carry out a really useful study.  We need the evidence.

Petti, S. (2015). Over two hundred million injuries to anterior teeth attributable to large overjet: a meta-analysis Dental Traumatology, 31 (1), 1-8 DOI: 10.1111/edt.12126

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There Are 4 Comments

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  1. Laurin Rackham says:

    200+million/ 1 yr? 20 yrs?

  2. Gareth Wallis says:

    I am inclined to agree with you concerning the 3-4mm overjet. I am not sure any orthodontist would regard this anything like a significant overjet, yet it has an odds ratio of 2.01. Does this mean that a very considerable proportion of the 200million fractures had overjets of less than 4mm? Perhaps we should take the view that whilst this is most unfortunate for the patients concerned, orthodontics doesn’t have a role in preventing these fractures?
    Perhaps more revealing is that the odds increase by 0.23 (23%)for overjets of 6mm and it is to these patients that we should be aiming our advice and possible treatment?

  3. Daniele Raviglia says:

    Dear Prof O’Brien,
    Last week I attended a nice conference that was held in Florence.
    I have noticed that if you are going to act early in the class II malocclusion to reduce the incisor trauma risk you use the Twin Block.
    If I’m not mistaken there is no evidence supporting the “clinical superiority” of any functional device including extraoral traction (which I prefer to use). So what is the reason for your clinical choice?
    Best regards

    • Kevin O'Brien says:

      Hi Daniele, thanks for the comments. You have raised a good point and this is where clinical experience comes into play. As we discussed this has a role in evidence based care and my clinical preference is to use the Twin Block but I explain to my patients that there are other methods and this is just my preferred option.

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