Does Orthodontic Treatment Provide Long-term Improvements in Patients' Self-esteem and Oral Health-related Quality of Life? A Literature Review

Studies examining effect on oral health-related quality of life (Table 1)

A study of 1675 Brazilian adolescents in 2004 found that participants who had completed orthodontic treatment were 1.85 times less likely to report oral health impacts than those currently under treatment, and 1.43 times less likely than those who never received treatment.²² Differences in OHRQoL were mostly related to activities such as smiling, laughing and showing teeth without embarrassment. The large sample size and the excellent response rates were the main strengths of this particular study. In agreement with these findings, Palomares et al reported that adults who had not received orthodontic treatment displayed OHIP scores five times those of their treated counterparts, indicative of significantly poorer OHRQoL.²³ A number of limitations to this study is however evident: in addition to small sample size, the ‘untreated control group’ comprised patients from the university's orthodontic waiting list, which may have resulted in participants reporting exaggerated oral health impacts in an attempt to enhance their priority level for treatment.

While both of these studies used validated measures to indicate that orthodontic treatment improves OHRQoL, their cross-sectional design restricted the possibility of drawing conclusions regarding the long-term effect of orthodontic treatment on OHRQoL.

Three longitudinal studies supported orthodontic treatment improving patients' OHRQoL. Feu et al²⁴ observed a 60% reduction in the OHIP-14 scores of participants following orthodontic treatment. The study's two control groups – those awaiting treatment and those who never sought treatment – showed slightly increased scores over the follow-up period. Only half of participants receiving treatment, however, had the treatment completed by the end of the study. As participants were not allocated randomly into treatment and control groups, a further limitation relates to the possibility of selection bias. In 2010, Chen et al²⁵ found that mean OHIP-14 scores reduced significantly from 8.65 pre-treatment to 2.65 post-treatment. Both of these studies had high response rates, used validated measures and present higher levels of evidence than cross-sectional designs. Short follow-up periods, however, prevent conclusions in relation to the long-term effect of orthodontic treatment on OHRQoL. While Healy et al²⁶ found only a slight increase in OHRQoL immediately after debond in 104 patients, there was a substantial increase in OHRQoL when measured at 2 years post-treatment.²⁶

The findings of the above studies were disputed by Taylor et al and Agou et al.^27,28 In 2009, Taylor et al found no significant differences in OHRQoL between adolescents either awaiting treatment, had completed treatment or were not actually seeking treatment²⁷. Despite this finding, self-reported improvements were noted in the treatment group with regard to oral appearance, function, health and social wellbeing.²⁷ This study's cross-sectional design was a major limiting factor. Agou et al²⁸ carried out a longitudinal study in 2011, the results of which suggested a significant difference in CPQ11–14 scores between treated and untreated groups. Interestingly, when the children's psychological wellbeing was considered as a covariant, the effects of treatment on OHRQoL status was no longer found to be significant.²⁸ This study highlights the importance of considering the impact of individuals' psychological characteristics on their perception of their OHRQoL status.

Studies examining effect on self-esteem (Table 2)

In a study of 172 adults, Pabari et al²⁹ found that participants who had completed orthodontic treatment expressed SE scores 2.4 points higher, on average, than those of pre-treatment or in-treatment groups. Similarly, Jung et al³⁰ reported increased SE levels in participants who had received orthodontic treatment; however, this improvement was gender-dependent and only observed in female participants. A large sample was this study's main strength. However, as neither of these studies collected data longitudinally, and considering that many confounding factors exist in establishment of individuals' SE levels, the difference in scores between treatment and non-treatment groups cannot be directly interpreted to be a result of treatment.

A multicentre, randomized control trial, carried out in 2003 in the UK, reported higher self-concept scores and a reduction in negative social experiences as a result of early treatment of Class II division 1 malocclusions with twin block appliances.³¹ Conflicting results were found in a similar study carried out by Dann et al³² who concluded that early orthodontic growth modification did not exert an effect on self-concept scores. As mean overjet reduction was much greater in the more recent study, it is possible that the changes in smile aesthetics achieved by Dann et al were below the threshold to affect self-concept scores. Both of these studies again have the recurring limitation of short follow-up periods.

Varela et al,³³ Birkeland et al³⁴ and Avondroodt et al³⁵ carried out longitudinal studies that failed to show that orthodontic treatment exerts any influence over an individual's SE. While Varela et al³³ noted improvements in facial and overall body image of participants, SE levels did not change over the observational period. Small sample size, limited male participation and very short follow-up periods comprise the main limitations of this study. Birkeland et al³⁴ stated that improvements in adolescents' SE levels over their study's follow-up period were a result of age-related changes and not related to orthodontic treatment status. Participants did, however, report higher self-confidence as a result of obtaining treatment, with this effect particularly evident among girls.³⁴ While an extended follow-up period was employed compared to the other reviewed studies, 4 years remains inadequate to judge the long-term psychological benefits of treatment. Avondroodt et al³⁵ agreed with the above findings in that no changes in SE were recorded throughout and after orthodontic treatment, concluding that SE acts as a protective factor during orthodontic treatment. Although this study was prospective and had a large sample size, there was a high dropout rate of 63%, and patients were only followed-up until 1 month post-treatment.³⁵

Studies examining effect on self-esteem and oral health-related quality of life (Table 3)

Some studies have examined treatment effect on both SE and OHRQoL. Johal et al reported no improvements in OHRQoL scores but increases in SE scores as a result of treatment.³⁶ In contrast, Seehra et al found that interceptive orthodontic treatment in bullied adolescents resulted in significant improvements in OHRQoL, although no improvement in SE between pre- and post-treatment was noted.³⁷ Limited follow-up and small sample sizes were drawbacks of these studies. Jaeken et al³⁸ found an overall improvement in OHRQoL following orthodontic treatment with a reduction in CPQ11–14 scores after treatment. A greater improvement in OHRQol was reported when baseline SE was higher, again suggesting that SE has a protective effect on OHRQoL.³⁸ Despite the large sample size and prospective design, this study was limited by its short follow-up period, lack of control group and failure to specify the type of orthodontic treatment provided.

The Cardiff Dental Study followed participants for 20 years, the longest follow-up period of any of the reviewed studies. Similar to findings by Agou et al,²⁸ when SE at baseline was controlled for, orthodontic treatment was found to provide little benefit to psychological health and quality of life in adulthood. The authors concluded that lack of orthodontic treatment in cases where there was definitive objective need did not appear to lead to psychological difficulties later in life.^18,39 Several limitations are apparent in this study, however. With less than one-third of the original cohort returning for follow-up, attrition rates were high. The study employed general health and not oral specific QoL measures, which may not have been sensitive to detect the full extent of change. A longitudinal study of comparable length was carried out between 1988 and 2006 in Australia.⁴⁰ However SE and OHRQoL measures were only carried out at follow-up, preventing the possibility of drawing any meaningful conclusions.

Studies examining effect on oral health-related quality of life (Table 4)

There appears to be a general consensus in the literature that orthognathic surgery increases patients' OHRQoL. Rustemeyer et al, Choi et al, Lee et al and Esperão et al all reported significant reductions in post-surgical scores for OHRQoL questionnaires.^41–44 Murphy et al⁴⁵ carried out the first longitudinal study involving an Irish population with dentofacial deformities. In agreement with other research, statistically significant differences indicative of improved OHRQoL were found post treatment. Researchers employed an array of validated generic health-, oral health-, and condition specific-QoL measures. Studies examining the effect of orthognathic surgery on patients' OHRQoL tend to use much smaller sample sizes than those examining the effect of conventional orthodontic treatment. The majority of studies are longitudinal in design; however, average follow-up periods range from only 6 to 12 months. The exception to this is a randomized clinical trial carried out by Motegi et al⁴⁶ which followed patients for 5 years after surgical intervention. All components of the Oral Health Status Questionnaire showed significant improvements at 5 years post-surgery, with improvements stable from 2 to 5 years.

Studies examining effect on self-esteem (Table 5)

There are few studies pertaining to the effect of orthognathic surgery specifically on SE. Nicodemo et al⁴⁷ found a minimal improvement in SE of female patients following surgery. Although this study used a validated measure, and was of longitudinal design, short follow-up period and small sample size present limitations. Palumbo et al⁴⁸ supported the latter's findings where two-thirds of patients in the study reported improved SE following treatment. This study is constrained by its cross-sectional design, lack of control group, use of a non-validated measure and small sample size.

Summary of main results

While there is a general consensus in the literature that orthognathic surgery improves patients' OHRQoL,^41–45 conflicting reports exist regarding the effect of conventional orthodontic treatment. Some studies have reported significant enhancements in OHRQoL,^22–25,37 whereas others have found no discernible change.^27,28,36 Where improvements have been reported, they tend to be related to the psychological discomfort domain scores of OHRQoL measures.

Similarly, findings in the literature are inconsistent regarding the effect of conventional orthodontic treatment on SE. Some studies report significant increases in participants' SE levels following treatment,^29,31,36 while others have found no apparent difference.^{18,32–34,37,38}. Only two studies have examined the effect of orthognathic surgery on SE specifically. Both observed increases in SE on completion of treatment.^47,48

As dentofacial changes are much greater following orthognathic surgery compared to conventional treatment, it is unsurprising that more consistent changes in OHRQoL and SE measures are reported following surgical intervention.

Quality of evidence

The quality of evidence presented by the reviewed studies regarding the long-term effects of orthodontic treatment on SE and OHRQoL is low. The majority of studies employ validated OHRQoL and SE scales; however, an array of different scales are used in the literature making it difficult to accurately compare the results. As SE and OHRQoL cannot be objectively measured, research relies on subjective reporting, which leads to the problems of self-presentation and disclosure. The data collected represent what study participants are prepared to say about themselves to a third party, rather than a true reflection of self.

While OHRQoL is a relatively well-defined construct, the concept of SE is considerably more ambiguous. A great number of factors affect SE, each to varying degrees in different individuals. It is a difficult task to isolate the effect of one particular variable (ie orthodontic treatment) on SE levels. The contribution of dentofacial appearance to an individual's SE is exceedingly difficult to determine.

Due to ethical constraints orthodontic research does not frequently lend itself to randomized control trials.⁴⁹ Strength of evidence suffers as a result. Cross-sectional studies present inherent limitations and many of the longitudinal studies are of short duration. The only long-term study examining the effects of orthodontic treatment on QoL found no apparent changes; however, general health-rather than oral health-related measures were employed.^18,39

Further considerations

An important point to consider is that lack of objective change in OHRQoL or SE measures following intervention may not necessarily be a poor reflection on orthodontic treatment, but may simply be a product of human behaviour. Diener et al stated that ‘good and bad events temporarily affect happiness, but people quickly adapt back … individual and societal attempts to increase happiness are doomed to failure’.⁵⁰ Many psychologists believe that an individual's SE and general wellbeing remain reasonably stable throughout life and are not readily altered.¹⁰ As orthodontic treatment occurs over a number of years, patients have time to adjust back to their ‘set point’. They may have forgotten their initial malocclusion or have already adapted to the final treatment result, and as such, one should not expect changes in psychological measures following treatment.

Implications for practice

It is essential for good practice to provide patients with insight into evidence-based benefits from orthodontic treatment, allowing them to make fully informed decisions prior to receiving treatment. If orthodontic treatment provides a purely cosmetic benefit, and cannot be shown to have significant quality of life benefits, it brings into question the justification for its inclusion in publicly funded healthcare.

Implications for research

Studies in the dental literature have yet to provide conclusive evidence for psychosocial benefits from orthodontic treatment. A number of limitations of the existing research have been highlighted throughout this review. More research is required in this area to confirm and validate the longevity of treatment effects on both SE and OHRQoL. Well-controlled, long-term longitudinal studies that employ validated measures relevant to the study population will eventually improve our knowledge in this area