Orthodontic treatment and dental health: Chasing rainbows?
Most of us regularly undertaking orthodontic treatment do so with a conviction that we are making a difference. We routinely produce definite cosmetic improvement, particularly in those initially presenting with severe malocclusion. But does malocclusion of itself lead to adverse dental health? Moreover, does the correction of malocclusion produce an improvement in dental health?
These questions are particularly pertinent to those of us providing orthodontic treatment as part of a public healthcare system. Public expenditure on orthodontic treatment in England, for example, was estimated at £275m in one financial year (2015-2016). Previous studies have attempted to evaluate links between orthodontic treatment and measures of disease including dental caries, gingivitis and periodontal disease, as well as the potential for a reduction in incidence and severity of dental trauma. More recently, the possible benefit of orthodontic treatment on quality of life has generated increasing interest. This is based on the premise that a state of health encompasses more than the absence of disease and should reflect the ‘physiologic, social and psychosocial attributes that are essential to the quality of life’.
This paper represents an attempt to combine this information within a systematic review. A research team based in Manchester, UK, and Rio de Janeiro did the review.
Manchester is a wonderful, vibrant city in the North-West of England. It is home to some of the best bands including The Smiths, The Stone Roses and Oasis. It is also very close to Liverpool, home to the best football team in Europe, for a while.
Authors: Richard Macey, Badri Thiruvenkatachari, Kevin O’Brien, and Klaus Batista
Am J Orthod Dentofacial Orthop 2020;157:738-44
What did they do?
They conducted a systematic review to assess the impact of both malocclusion and orthodontic treatment on oral health. Importantly, this included their effects on oral health-related quality of life.
As the study involved two parts, the selection criteria were extensive with those involving assessment of the effect of malocclusion on oral health (Part 1) including:
- any study investigating the association between malocclusion and oral health at a single time point;
- a comparison group with no malocclusion; and
- use of a validated tool, e.g. IOTN, Dental Aesthetic Index (DAI) or an accepted objective measurement (e.g. overjet).
As such, they hoped to include baseline data from randomised controlled trials, prospective cohort studies with untreated controls, and cross-sectional studies involving a control group with no malocclusion.
To evaluate the effect of orthodontics on oral health (Part 2), they wanted to include studies assessing the oral health of participants before and after an orthodontic intervention with an untreated control. Therefore, relevant study designs were randomised controlled trials and prospective cohorts involving two-time points (before and after treatment) with an untreated control group.
Outcomes: They classified the outcomes into those relating to dental health as well as social and quality of life impacts. Specific outcomes were to include caries, periodontal outcomes, plaque levels, the occurrence of trauma and oral health-related quality of life outcomes.
They did separate searches for both parts of the review with tailored quality assessment tools used to grade the quality and risk of bias of primary studies.
What did they find?
The authors identified 87 studies relating to the effect of malocclusion on oral health; of these, five were longitudinal in design with 82 being cross-sectional. A range of outcomes was assessed with quality of life considered within 41 studies. In terms of dental trauma, the reviewers found a higher odds of dental trauma (OR: 1.98; 95% CI: 1.8, 2.17) for overjet above 5mm based on data from 21,065 participants. However, they also identified limited data relating to the effect of malocclusion on periodontal health or caries. They found a significant number of studies involving the evaluation of the quality of life effects; however, they could not do a meta-analysis because the studies used composite scores, a range of outcome measures and malocclusion types.
They found little information concerning the association between orthodontic treatment and caries or periodontal outcomes. Slightly more data was available about possible effects of orthodontics on quality of life; however, a meta-analysis was not deemed possible as there were differences in the outcome measures used. The authors reported a 12% reduction in the prevalence of trauma (31.7% to 19.7%). This has been published in a previous systematic review.
The authors concluded the following:
‘.. apart from trauma, there is an absence of evidence on the effects of malocclusion on oral health and the impact of orthodontic treatment on oral health.’
What did I think?
I thought that this was a wide-ranging and ambitious review. The authors asked two distinct (but related) questions giving us lots of information to digest. The findings, however, are relatively disappointing. We have little evidence to confirm my firm belief- that we do make a very significant difference to the lives of many (but certainly not all) of the patients we treat. This paper is, therefore, one of those that prompts more questions than answers. Do we make a health difference? If so, why are we unable to confirm this?
As the authors suggest, we lack vital studies evaluating the effect of malocclusion on dental health. These studies are challenging to do. The prolonged periods of follow-up required for particularly informative longitudinal studies may deter researchers. Furthermore, the identified studies involved a range of different outcomes making comparison particularly tricky. The advent of an orthodontic Core Outcome Set (which should be published in the coming months) may help to address this problem.
The authors were also unable to identify many studies evaluating the effect of orthodontics on dental health. Those that do attempt to pinpoint possible benefits are again often inconsistent but crucially also involve patients with malocclusion of varying levels of severity. This quandary reflects the need for a more holistic index to measure both orthodontic treatment need and implications of malocclusion.
We also know that many of our patients seek treatment for cosmetic benefit only. We may, therefore, provide treatment to address ‘want not need’ and we cannot reasonably expect to produce a health benefit in these instances. However, at the other end of the spectrum, we also see adolescents subject to relentless bullying due to malocclusion. Our treatment can be life-changing for many of them. So perhaps we are victims of our success and popularity? Demand for treatment outstrips need, and maybe we struggle to isolate health benefit on a broader scale as many of these studies encompass an array of presentations.
What can we conclude?
The evidence relating to the health impact of malocclusion and the associated benefit of orthodontics is limited, with only a reduced trauma risk proven at this stage. Absence of evidence does not imply evidence of absence. It is a truism, but more research is undoubtedly required …..
Professor of Orthodontics, Queen Mary University of London, UK