Orthodontics improves oral health-related quality of life: fad, fact or fallacy?

For several years there has been a significant interest in establishing the health benefits of orthodontic treatment.¹ While these were traditionally explored using clinician-based outcome measures, in recent years, we have witnessed a paradigm shift with stakeholders agreeing that potential benefits should also be explored from the perspective of patients themselves. As such, within the orthodontic literature, we have seen an exponential increase in the use of patient-reported outcome measures (PROMs) and, in particular, ‘oral health-related quality of life’ (OHRQoL).

OHRQoL aims to provide a subjective evaluation of an individual's oral status, with a particular emphasis on the impact of oral conditions or treatments, on social and emotional wellbeing, oral symptoms and functional limitations.² This is demonstrated accurately by what is now considered a universally accepted definition of OHRQoL:³

‘The impact of oral diseases and disorders on everyday life that a patient or person values, that are of sufficient magnitude, in terms of frequency, severity or duration to affect their experience and perceptions of their life overall.’

When we consider the literature on orthodontic treatment and OHRQoL, more often than not, these studies broadly aim to address one of three possible questions:

• Does the presence of a malocclusion have an impact on OHRQoL?
• Do orthodontic appliances have an impact on OHRQoL during treatment?
• Does orthodontic treatment lead to an improvement in OHRQoL following the completion of treatment?

Although it is beyond the scope of this article to systematically review the literature pertaining to these three research questions, the article explores and highlights some of the existing literature in this field.

The impact of malocclusion on OHRQoL

Numerous studies, often cross-sectional in nature, have explored the impact of malocclusion on OHRQoL.^4,5 Such studies have typically recruited appropriate samples from the population to represent individuals with and without an orthodontic treatment need, with comparisons being made between the OHRQoL of these groups.^4,5,6 Several of these studies have consistently found that individuals with malocclusions have worse levels of OHRQoL than those without.

Over the past two decades, at least four systematic reviews have explored the impact of malocclusion on OHRQoL, and all of these have reached similar conclusions regarding the detrimental impact that malocclusions can have.^7,8,9,10 One of these systematic reviews included 40 studies and carried out a meta-analysis combining the data from 9293 young people with malocclusions and 10,717 without malocclusions.⁸ Using this data, the authors found that children and adolescents with malocclusions were 1.74 times more likely to experience a negative impact on their OHRQoL.⁸ Furthermore, there is now evidence that the dimensions of OHRQoL most significantly affected by malocclusions are social and emotional wellbeing.¹⁰ These findings are perhaps unsurprising given that in the orthodontic literature, the most common motivating factor for undergoing orthodontic treatment is a desire to improve dental appearance, and not to relieve oral pain (oral symptoms) or improve dental function (functional limitations).¹¹ Overall, based on the research evidence available to date, it is reasonable to conclude that the presence of a malocclusion can have a negative impact on OHRQoL, particularly in the dimensions of emotional and social wellbeing.

The impact of orthodontic appliances on OHRQoL

As orthodontic treatment is often considered elective in nature, it is important that clinicians fully appreciate the impact of orthodontic appliances on the OHRQoL of patients. It is imperative that the research data we have in this field is interpreted correctly, and in a manner that can be discussed with patients and/or their parents appropriately. Although there have been a number of cross-sectional studies exploring the impact of fixed appliances on OHRQoL, longitudinal studies are often more useful because they can offer greater insight into the level of impact at different time points during treatment. One such study, carried out in the UK, examined OHRQoL levels at baseline, 6 weeks and 3 months after the placement of fixed orthodontic appliances in adolescents aged 11–14 years.¹² The appliances were found to impact negatively on OHRQoL during the early stages of treatment, with significant impacts witnessed in the dimensions of oral symptoms and functional limitations. Similar results have also been found in a systematic review where the authors concluded that the negative impacts on OHRQoL were most significant during the first month of treatment, but these seemed to reduce as treatment continued.¹³

With our orthodontic armamentarium continuously evolving, it is important that new forms or protocols of treatment are thoroughly evaluated, not only with regard to clinical efficiency and efficacy, but also in terms of PROMs. A recent study compared the effect of twin block functional appliances versus fixed orthodontic appliances on the OHRQoL of adolescents undergoing treatment for a Class II division 1 incisor relationship.¹⁴ The authors assessed ORHQoL levels before, during and at the end of treatment. The patterns of OHRQoL were similar in both groups: OHRQoL became worse during the initial stages of treatment and then improved as treatment progressed, with no significant differences found between the two groups, compelling the authors to conclude that either approach to the management of such malocclusions was equally acceptable to patients.¹⁴

Similar results have also been observed when conventional brackets have been compared to self-ligating brackets in a prospective longitudinal cohort study.¹⁵ In both groups, the OHRQoL of participants was measured at 1 week, and 1, 3 and 6 months after appliance placement, as well as after treatment completion. The authors found no significant difference in OHRQoL between the two groups, but found that in both groups, OHRQoL was significantly worse at 1 week and 1 month compared to other time points.¹⁵

Based on the evidence available to date, it would appear that orthodontic appliances have a negative impact on the OHRQoL of patients, particularly in the dimensions of oral symptoms and functional limitations. These impacts seem to be most profound during the initial stages of treatment. However, patients can be reassured that this is only temporary in nature, and that with time, OHRQoL levels appear to improve.

OHRQoL following the completion of orthodontic treatment

As we now know from the research, there is evidence that malocclusion has a negative impact on OHRQoL, and that orthodontic appliances impact negatively on the OHRQoL of patients. However, there is a paucity of evidence on whether the completion of orthodontic treatment leads to an improvement in this multidimensional construct.

A recent systematic review identified 13 studies (six of which were included in a meta-analysis) assessing the OHRQoL of young people following the completion of orthodontic of treatment.¹⁶ Although the evidence identified by the review was deemed to be of low or moderate quality, it did suggest that orthodontic treatment provided during childhood or adolescence may lead to moderate improvements in OHRQoL. Interestingly, the dimensions of OHRQoL that showed the most significant improvement were emotional and social wellbeing.¹⁶ The review highlighted the need for further longitudinal studies, using malocclusion-specific OHRQoL outcome measures. The inclusion of an appropriate control group in such studies is also of particular importance. A 3-year cohort study following schoolchildren aged 11–12 years found that OHRQoL improved during the study period, regardless of whether the children had undergone orthodontic treatment.¹⁷ The findings of this study suggest that a natural improvement in OHRQoL can occur during adolescence.¹⁷ If an improvement in OHRQoL is found following the completion of orthodontic treatment, it is important that the OHRQoL levels of a control group that includes participants with comparable malocclusions is also incorporated in order to determine whether a potential observed improvement in the treatment group can, in fact, be attributed to the treatment alone.

The systematic review published also suggested that if an improvement in OHRQoL following orthodontic treatment is established, it is important that future studies seek to assess whether specific types of malocclusion benefit the most.¹⁶

Conclusion

There is little doubt that this area of research is fraught with its own unique challenges. In particular, it is well established that there are several non-clinical determinants of OHRQoL such as self-esteem, psychological wellbeing and socio-economic status that must be accounted for when exploring the relationships between malocclusion/orthodontics and OHRQoL.^18,19,20

There is currently a substantial body of evidence to suggest that malocclusion has a negative impact on OHRQoL, particularly in the dimensions of emotional and social wellbeing. Additionally, orthodontic appliances also appear to have a negative impact on the OHRQoL of children, adolescents and adults undergoing treatment, although this tends to occur during the early stages of treatment and then improves.

To date however, while there is some evidence that the completion of orthodontic treatment can lead to an improvement in OHRQoL, particularly in the dimensions of emotional and social wellbeing, this evidence is only of moderate/low quality. It is, without doubt, this area of research that will need to expand in the future, with studies that will not only determine whether improvements in OHRQoL are observed, and if so, whether particular characteristics or types of malocclusion can help predict those who will benefit the most from orthodontic treatment.