The European Journal of Orthodontics Advance Access published February 19, 2015 European Journal of Orthodontics, 2015, 1–8 doi:10.1093/ejo/cju092
Impact of self-esteem and personality traits on the association between orthodontic treatment need and oral health-related quality of life in adults seeking orthodontic treatment Maïté Clijmans*, Jurgen Lemiere**, Steffen Fieuws*** and Guy Willems* *Department of Oral Health Sciences – Orthodontics, Katholieke Universiteit Leuven & Dentistry, University Hospitals Leuven, **Child and Adolescent Psychiatry/Pediatric Haemato-Oncology, UZ Gasthuisberg – Katholieke Universiteit Leuven, ***Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Katholieke Universiteit Leuven and Universiteit Hasselt, Belgium Correspondence to: Guy Willems, Department of Oral Health Sciences – Orthodontics, Katholieke Universiteit Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium. E-mail: [email protected]
Summary Objective: The aim of this study was to investigate whether an association exists between orthodontic treatment need and oral health-related quality of life (OHRQoL) and whether this association is moderated by self-esteem (SE) and/or personality traits. Materials and methods: In this cross-sectional study comprising 189 adults (55 males and 134 females) aged 17 or older (mean age 31.3 years), the OHRQoL was scored by the use of the shortened version of the Oral Health Impact Profile-14 (OHIP-14). The Rosenberg self-esteem scale was used to evaluate SE, and the Dutch adaptation of the Neuroticism Extraversion Openness Five-Factor Inventory was used to assess personality profiles. Need for treatment was defined by the Index of Orthodontic Treatment Need. Spearman correlations, Mann–Whitney U-tests, and regression models were used to analyse the data. Results: There is a modest to weak association between treatment need (Dental Health Component and aesthetic component) and OHRQoL as measured by the total OHIP-14 score (ρ = 0.21, P = 0.01216; ρ = 0.18, P = 0.02960, respectively). A significant, yet modest to weak, association between SE and the total OHIP-14 score was found (ρ = −0.34, P = 0.00057). Moreover, significant associations were found for the total OHIP-14 score and neuroticism and extraversion. Significant associations can be found between SE and all personality traits. Conclusions: There was a significant association between orthodontic treatment need and OHRQoL. Moreover, a significant association can be found between SE and OHRQoL, as well as certain personality traits and OHRQoL. No evidence was found that SE or personality traits moderate the association between OHRQoL and treatment need.
Introduction Malocclusions are considered to be deviations from the aesthetic norm in a society rather than a disease. Nonetheless, there has been a long marked demand for orthodontic care (1–3). Visible occlusal
irregularity may be the most important reason to seek orthodontic treatment (4). However, reality seems to be more complex since some adults are complaining about minor aesthetic problems, while others with severe malocclusions do not seem to be bothered at all.
© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: [email protected]
2 The individual’s adjustment to his own imperfections in dental alignment is variable and there is no evidence that people with visible irregularities will in general be emotionally affected (5). Several indices have been developed throughout the years to objectify orthodontic treatment need, including the Index of Orthodontic Treatment Need (IOTN) (6). The IOTN determines the treatment need based on the Dental Health Component (DHC) as well as the Aesthetic Component (AC) of the dentition. Both are assessed by the clinician. Unfortunately, such traditional indices do not give any information about the impact of malocclusion on the patient’s quality of life in terms of limited function and psychosocial well-being (7). The interest in these aspects increased considerably in the past decade, with a shift in orthodontics from a more traditional biomedical model towards a more biopsychosocial model (8). The term ‘health-related quality of life’ (HRQoL) was introduced to describe an individual’s evaluation of his or her well-being on several domains: experience of pain/discomfort, physical function, psychological, and social function (9). Oral health-related quality of life (OHRQoL), therefore, is a multidimensional concept, which can help us understand the demand of orthodontic treatment beyond clinical parameters and sheds light on the effects of malocclusion on people’s lives (10). Positive OHRQoL can be defined as the absence of negative impacts of oral conditions on social life and a positive sense of dentofacial self-confidence (11). In order to analyse the effects of orthodontic treatment on psychological health, one must consider intervening factors (12). One of these factors, namely self-esteem (SE), can be defined as ‘the perception of one’s own ability to master or effectively deal with the environment and is affected by the reactions of others towards an individual’ (13). Still, there is no definite evidence that orthodontic treatment can improve one’s SE (12–15). However, it has been demonstrated that SE is a relatively stable construct (16). Additionally, there is evidence that SE might influence the effects of conditions or events, such as disease (8, 17–20). To our knowledge, no studies have investigated the potential role of SE on OHRQoL in adults seeking orthodontic treatment. Another factor to consider is one’s personality. A commonly used definition of personality is ‘more or less stable, internal factors that make one person’s behaviour consistent from one time to another, and different from the behaviour other people would manifest in comparable situations’ (21). As for SE, personality traits have been shown to be relatively stable throughout adulthood (22–24). Crosssectional reports recognized the effects of innate personality traits on children’s perceptions of dentofacial aesthetics and patients’ evaluations of the impact of their health on daily functioning (24). According to Thomson et al. (25), three processes can be involved in the association between personality and oral health. First, personality traits may predispose to poor oral health. Second, personality traits can be associated with health-damaging acts and thus predispose to poor oral health. Third, personality traits may shape one’s reaction to or interpretation of symptoms and thus create their state of illness. For example, a person with a high stress reaction might interpret oral symptoms as being more catastrophic. Of the three possible mechanisms described above, the first and second are related to the influence of personality on clinical disease status, and the third has the greatest immediate relevance to the issue of the influence of personality differences on oral health measurements using OHRQoL scales. Although there has been extensive research concerning the topic of OHRQoL, the focus of most research projects was children (26–28). While it is true that most of the orthodontic patients are
European Journal of Orthodontics, 2015 children, more and more adults seek orthodontic treatment (29). Moreover, most studies with adults aimed to investigate the association with orthognatic surgery rather than orthodontic treatment need per se (28, 30). Therefore a cross-sectional study was initiated with adults. The aim of this study was to investigate whether an association exists between orthodontic treatment need and OHRQoL in adults and whether this association is influenced by SE and/or personality traits.
Subjects and methods Every healthy adult (17 years or older) registered for a first assessment visit at the Orthodontic Department of the University Hospitals of Leuven (Belgium; between November 2011 and January 2014) was kindly requested to complete a questionnaire. Adults with a psychological condition or adults who did not have thorough knowledge of the Dutch language to fully understand the questions were excluded. No distinction was made between orthodontic or combined orthodontic–orthognatic patients. Age and gender were recorded because of their potential associations with existing variables. The study protocol was approved by the Committee of Medical Ethics of the University Hospitals of Leuven (B322201112307). An informed consent was obtained from all participants. The OHRQoL of the adults was scored by the use of the Dutch translation of the Oral Health Impact Profile-14 (OHIP-14). The OHIP-14 (31) is a shortened version of the OHIP-49 (32). It is based on a subset of two questions for each of seven conceptual dimensions of OHRQoL. These dimensions are functional limitations, physical discomfort, psychological discomfort, physical disability, psychological disability, social disability, and handicap. Questions have to be answered on a 5-point ordinal scale (never, hardly ever, occasionally, fairly often, and very often), with a total score ranging from 0 to 56. Higher OHIP scores indicate a worse OHRQoL. The Dutch OHIP-14 has been found to be a valid and reliable tool to quantify OHRQoL (33, 34). The Rosenberg self-esteem scale (RSES) is a widely used instrument for assessing global SE. The RSES measures an adult’s global feelings of self-worth or self-acceptance. It consists of 10 items with total scores ranging from 0 to 30 with higher scores indicating higher SE (35, 36). The RSES is a reliable and validated tool to examine one’s SE in English as well as in Dutch (37, 38). The Dutch adaptation of the Neuroticism Extraversion Openness Five-Factor Inventory (NEO-FFI) was used to assess personality profiles (39). The Big Five personality dimensions comprise one of the most commonly used personality taxonomies. This test consists of 60 questions analysing the five basic dimensions of someone’s personality: neuroticism, extraversion, openness, agreeableness, and conscientiousness. The raw scores were converted into norm-referenced scores by using the age and gender norms (separately) of the Dutch adaptation of the NEO-FFI (40). There are no available norms that consider age and gender together. A score of 5 is an average score, while 1 = very low, 2 and 3 = low, 4 = low average, 6 = high average, 7 and 8 = high, and 9= very high. Clinical examination by calibrated orthodontists in training, supervised by one professor (certified in the UK in 1993), was undertaken to assess the Dental Health Component (DHC) and aesthetic component of the IOTN of each participant. The DHC of the IOTN is a 5-grade index that records the dental health need for orthodontic treatment. The aesthetic component (AC) records the aesthetic need for orthodontic treatment on a scale of 10 photographs showing different levels of dental attractiveness (6). An IOTN DHC score of
M. Clijmans et al. 3 or greater and an IOTN AC score of at least 5 were considered as clinical need for treatment (26).
Statistical analysis All analyses were performed using SAS software, version 9.2 of the SAS System for Windows. Groups were compared with Fisher’s Exact and Mann–Whitney U-tests. Spearman correlations were used to evaluate associations between variables on ordinal or continuous scale. Linear regression models were used to verify if the association between OHIP and treatment need is moderated by SE (Rosenberg) or norm-referenced personality scores (norm reference on age or gender). Hence, interest was in the potential interaction with treatment need. Age and gender were added in all models as main effects. Results are given with AC and DHC on original scale and after dichotomization. P values smaller than 0.05 were considered significant. Corrections for multiple testing (false discovery rate) were done. The sample size was determined on practical considerations, namely, every healthy adult was asked to complete the questionnaires between November 2011 and January 2014. The sample size was not explicitly based on a priori sample size calculation. For example, with a sample size of 189, the present study had 80 per cent power to detect a moderation effect in the regression model with a semi-partial correlation of 0.205.
Results In total, 189 adults, 55 males (29.1 per cent) and 134 females (70.9 per cent), with a mean age of 31.3 years (SD: 12.3; range: 17–64 years) completed the questionnaires. The majority of them were Caucasian (167; 88.4 per cent) and 22 (11.6 per cent) were of
other ethnic origins. Fifty-five adults were found to have need for combined orthodontic–orthognatic treatment. Descriptive statistics for the main variables, namely OHRQoL, orthodontic treatment need, SE, and personality traits are presented in Table 1. Total OHIP-14 scores range from 0 to 39 with a mean of 10.7 (SD: 8.0) with no significant differences according to gender or age group. The age group above 50 years shows a higher OHIP14 score, indicating a worse OHRQoL than the other age groups. The AC and DHC of IOTN showed a mean of approximately 4.0 (SD: 2.2) and 3.3 (SD: 1.0), respectively, and this did not differ significantly over all three age groups or gender. All levels of severity are present in the sample as shown in Table 2. 79.36 per cent can be classified as having need for orthodontic treatment according to the DHC of the IOTN, while only 38.09 per cent has a need for orthodontic treatment according to the AC of the IOTN. Regarding SE, the scores range from 0 up to 30 with a mean of 21.1 (SD: 5.2). Most of the personality traits range from 1 up to 9 and have varying means. The results are rather similar for men and women and according to the different age groups. According to the univariate analyses, there is a modest to weak association between treatment need and OHRQoL as measured by the total OHIP-14 score (Table 3). When there is a higher treatment need, the OHIP-14 scores are higher, thus indicating a worse OHRQoL. For the different domains of the OHIP-14, significant associations can be found for the functional limitations, physical discomfort, psychological discomfort, and psychological disability domains. These associations also appear to be moderate to weak. After dichotomizing the IOTN scores [DHC < 3 (n = 39) versus DHC ≥ 3 (n = 150); AC < 5 (n = 117) versus AC ≥ 5 (n = 72)], evidence for a difference in OHIP between both groups diminishes.
Table 1. Descriptive statistics for the main variables. OHRQoL, oral health-related quality of life, domain scores and total score of the oral health; OHIP-14, Oral Health Impact Profile-14; orthodontic treatment need as judged by the Dental Health Component (DHC) and aesthetic component (AC) of the Index of Orthodontic Treatment Need (IOTN); Rosenberg SE, Rosenberg self-esteem scale and Big Five personality traits (gender and age referenced). Variable OHRqOL (OHIP-14) Functional limitations Physical discomfort Psychological discomfort Physical disability Psychological disability Social disability Handicap Total Treatment need (IOTN) DHC AC Rosenberg SE Personality Neuroticism (gender) Extraversion (gender) Openness (gender) Altruism (gender) Conscientiousness (gender) Neuroticism (age) Extraversion (age) Openness (age) Altruism (age) Conscientiousness (age)
Mean women (SD)
Mean men (SD)
Mean age group 50 years (SD)
0.6 (1.3) 2.2 (1.8) 3.0 (2.1) 0.8 (1.3) 2.1 (1.7) 1.0 (1.4) 1.0 (1.4) 10.7 (8.0)
0.5 (1.2) 2.2 (1.9) 3.1 (2.1) 0.9 (1.4) 2.2 (1.6) 1.0 (1.4) 0.9 (1.3) 10.7 (7.8)
0.5 (1.2) 2.2 (1.9) 2.7 (2.1) 0.7 (1.2) 2.1 (1.9) 0.9 (1.4) 1.3 (1.7) 10.7 (7.9)
0.5 (1.0) 2.3 (1.7) 3.0 (2.2) 0.7 (1.2) 2.1 (1.8) 1.0 (1.4) 0.9 (1.4) 10.6 (7.4)
0.6 (1.2) 2.0 (1.9) 3.1 (2.1) 0.8 (1.4) 2.2 (1.7) 0.9 (1.4) 0.9 (1.4) 10.4 (8.2)
1.1 (2.1) 2.5 (2.0) 2.9 (1.8) 1.4 (1.6) 2.3 (1.9) 0.9 (1.4) 1.5 (1.6) 12.6 (9.0)
3.3 (1.0) 4.0 (2.2) 21.1 (5.2)
3.2 (1.0) 3.8 (2.1) 21.0 (5.3)
3.4 (1.1) 4.3 (2.2) 21.5 (5.0)
3.2 (1.1) 3.8 (2.3) 20.9 (5.3)
3.4 (1.0) 4.2 (2.0) 21.1 (5.2)
3.3 (1.1) 4.2 (2.3) 21.9 (4.7)
5.2 (1.8) 6.1 (2.0) 6.0 (1.7) 4.9 (2.1) 5.2 (2.2) 5.2 (1.8) 5.6 (2.0) 5.8 (1.8) 5.1 (2.1) 5.2 (2.1)
5.2 (1.8) 6.1 (1.9) 6.0 (1.7) 4.9 (2.1) 5.4 (2.2) 5.4 (1.8) 5.8 (1.9) 5.8 (1.8) 5.4 (2.1) 5.4 (2.0)
5.2 (1.9) 6.0 (2.2) 6.2 (1.7) 4.6 (2.2) 4.9 (2.3) 4.8 (2.0) 5.4 (2.3) 5.8 (1.9) 4.4 (1.9) 5.0 (2.2)
5.5 (1.8) 6.3 (2.1) 5.8 (1.7) 4.8 (2.1) 4.8 (2.2) 5.3 (1.9) 5.5 (2.2) 5.4 (1.8) 5.2 (2.0) 5.1 (2.0)
5.0 (1.9) 6.0 (1.9) 6.2 (1.8) 5.0 (2.1) 5.3 (2.2) 5.1 (1.8) 5.6 (1.9) 5.9 (1.8) 5.1 (2.1) 5.2 (2.2)
5.2 (1.6) 5.8 (1.8) 6.3 (1.6) 4.7 (2.3) 6.0 (1.9) 5.4 (1.8) 6.3 (1.8) 7.0 (1.7) 5.0 (2.4) 6.0 (1.9)
European Journal of Orthodontics, 2015
4 For SE and the total OHIP-14 score, univariate analysis indicated a significant, yet modest to weak, association: the higher the SE, the lower the OHIP-14 score, indicating a better OHRQoL. Significant associations can be found for all the different domains (Table 4). Although significant, these correlations seem to be modest to weak. Univariate analysis shows significant associations for the total OHIP-14 score and neuroticism (age and gender referenced), as well as extraversion (age and gender referenced) (Table 5). Moreover, Table 2. Distribution of participants according to the orthodontic treatment need. Treatment need (IOTN)
DHC DHC score 1 DHC score 2 DHC score 3 DHC score 4 DHC score 5 AC AC score 1 AC score 2 AC score 3 AC score 4 AC score 5 AC score 6 AC score 7 AC score 8 AC score 9 AC score 10
5.3 15.3 35.5 33.9 10.1 12.7 15.3 20.6 13.2 11.1 10.6 9.5 5.3 1.6 —
Orthodontic treatment need as judged by the Dental Health Component (DHC) and aesthetic component (AC) of the Index of Orthodontic Treatment Need (IOTN).
Table 3. Spearman correlations between OHRQoL and treatment need. AC, aesthetic component; DHC, Dental Health Component; IOTN, Index of Orthodontic Treatment Need; OHIP-14, Oral Health Impact Profile-14; OHRQoL, oral health-related quality of life. OHRQoL (OHIP-14)
Functional limitations Physical discomfort Psychological discomfort Physical disability Psychological disability Social disability Handicap Total
0.17, P = 0.03820 0.21, P = 0.00956 0.19, P = 0.02012 0.11, P = 0.16189 0.19, P = 0.0094 0.03, P = 0.71526 0.09, P = 0.23868 0.21, P = 0.01216
0.16, P = 0.04104 0.13, P = 0.09970 0.21, P = 0.01206 0.06, P = 0.53474 0.15, P = 0.06321 0.01, P = 0.91164 0.14, P = 0.07240 0.18, P = 0.02960
Table 4. Spearman correlations between OHRQoL and (Rosenberg) self-esteem (SE). OHIP-14, Oral Health Impact Profile-14; OHRQoL, oral health-related quality of life. OHRQoL (OHIP-14)
Functional limitations Physical discomfort Psychological discomfort Physical disability Psychological disability Social disability Handicap Total
−0.18, P = 0.02960 −0.26, P = 0.00139 −0.22, P = 0.00807 −0.22, P = 0.00901 −0.24, P = 0.00411 −0.26, P = 0.00106 −0.27, P = 0.00057 −0.34, P = 0.00057
significant associations are found between all the different domains of the OHIP-14 questionnaire and neuroticism (gender and age referenced). The associations between the psychological discomfort, physical disability, psychological disability, social disability, and handicap domain of the OHIP-14 and extraversion (gender and age referenced) are significant. Moreover, the functional limitation domain of the OHIP-14 questionnaire and extraversion (age referenced) are significantly correlated. For openness, a significant association can be found with the social disability domain, the same can be said for altruism and conscientiousness. On the other hand, the functional limitations and handicap domain of the OHIP-14 questionnaire are also significantly associated with altruism (age and gender referenced). Conscientiousness (age and gender referenced) is not only significantly correlated with the social disability domain but also with the handicap domain. The level of correlation varies from weak to moderate. Significant association can be found between SE and all the Big Five personality traits. This seems to be true for gender as well as age-referenced personality traits (Table 6). Neuroticism is negatively correlated with SE, while the other personality traits are positively correlated. Levels of correlation vary from weak to strong. No significant interaction between SE and treatment need could be found for the total OHIP-14 score, neither for the dichotomized DHC of the IOTN nor for the dichotomized AC of the IOTN after correction for multiple testing. When looking at the different domains of OHIP-14, no significant interactions can be found except between SE and the DHC for the handicap domain (P = 0.02913; Figure 1); this does not remain significant after correction for multiple testing. Thus, there is no evidence that the possible differences in OHRQoL between adults with and without treatment need depend on SE. Similarly for personality traits, only in one out of the tested settings, the P value for the interaction with treatment need seems significant (P = 0.04937). However, after correcting for multiple testing, this P value is no longer significant. Participants with a moderate to high treatment need (DHC) have a higher total OHIP-14 compared to participants with no or little treatment need. However, if neuroticism decreases the difference between both groups decreases (norm referenced on gender; Figure 2). After dividing the OHIP-14 in its different domains, other significant interactions can be found, but given the large amount of relations tested, no conclusion should be drawn from these P values. Hence, there is no evidence that the possible differences in OHRQoL between adults with and without treatment depend on one’s personality traits.
Discussion The results of our study demonstrated that there is a modest association between orthodontic treatment need and some aspects of OHRQoL. This finding can be confirmed by a systematic review (41). Moreover, the association between OHIP-14 and DHC appears to be stronger than the one between OHIP-14 and AC. Current results reveal a significant association between orthodontic treatment need and the following OHRQoL domains: functional limitations, physical discomfort, psychological discomfort, and psychological disability domain. Looking at the available literature employing similar tools for assessing orthodontic treatment need and OHRQoL, a variety of results can be found. In children and adolescents, most studies found a significant association between orthodontic treatment need and emotional well-being (26, 42–45). Two of these studies also found a significant association between OHRQoL and
M. Clijmans et al.
Table 5. Spearman correlations between oral health-related quality of life (OHRQoL) and personality traits (Big Five, norm referenced for gender). OHIP-14, Oral Health Impact Profile-14. OHRQoL (OHIP-14)
Functional limitations Physical discomfort Psychological discomfort Physical disability Psychological disability Social disability Handicap Total
0.21, P = 0.01095 0.21, P = 0.00807 0.31, P = 0.00057 0.18, P = 0.02590 0.30, P = 0.00057 0.33, P = 0.00057 0.23, P = 0.00545 0.37, P = 0.00057
−0.15, P = 0.06321 −0.15, P = 0.06600 −0.13, P = 0.09229 −0.17, P = 0.03050 −0.18, P = 0.02384 −0.26, P = 0.00139 −0.23, P = 0.00555 −0.23, P = 0.00392
−0.03, P = 0.71332 −0.01, P = 0.94480 0.02, P = 0.82783 −0.01, P = 0.94480 0.03, P = 0.71332 −0.19, P = 0.01790 0.02, P = 0.82783 −0.01, P = 0.89728
−0.19, P = 0.02133 −0.06, P = 0.51393 −0.04, P = 0.67722 −0.11, P = 0.16727 −0.01, P = 0.87870 −0.20, P = 0.01603 −0.18, P = 0.02305 −0.13, P = 0.09970
−0.16, P = 0.07300 −0.15, P = 0.06838 −0.05, P = 0.63592 −0.12, P = 0.12289 −0.04, P = 0.64403 −0.27, P = 0.00057 −0.20, P = 0.01454 −0.15, P = 0.06274
Table 6. Spearman correlations between personality traits (Big Five) and (Rosenberg) self-esteem (SE). Personality traits
Neuroticism (norm referenced for gender) Extraversion (norm referenced for gender) Openness (norm referenced for gender) Altruism (norm referenced for gender) Conscientiousness (norm referenced for gender) Neuroticism (norm referenced for age) Extraversion (norm referenced for age) Openness (norm referenced for age) Altruism (norm referenced for age) Conscientiousness (norm referenced for age)
−0.59, P = 0.00057 0.41, P = 0.00057 0.16, P = 0.04325 0.21, P = 0.01206 0.34, P = 0.00057 −0.57, P = 0.00057 0.4, P = 0.00057 0.1, P = 0.03365 0.18, P = 0.02590 0.34, P = 0.00057
social well-being (26, 42). For adults, a diversity of results can be found. Liu et al. (46) found significant associations between all the different domains of the OHIP-14 questionnaire and the DHC of the IOTN, while physical discomfort and physical disability were not significantly related to the AC of the IOTN. Hassan and Amin (10) reported that orthodontic treatment need significantly affected mouth aching, self-consciousness, tension, embarrassment, irritability in adult orthodontic patients, and life satisfaction and supports the assumption that orthodontic patients mainly suffer aesthetic and social problems rather than impairment of daily activities. A study by Rusanen et al. (47) on 151 adult patients with severe, diagnosed skeletal malocclusions who were referred for orthodontic or surgical-orthodontic treatment found physical discomfort, psychological discomfort, and psychological disability to be the most commonly perceived oral impacts. Masood et al. (48) reported that IOTN scores were most closely correlated with impact on psychological discomfort and functional limitation domains of OHRQoL in young adults. One must bear in mind that no distinction was made between orthodontic and orthodontic–orthognatic adult patients in order to get a better idea of the adult patient population as a whole. This may, however, influence the results and makes it difficult to compare our results with other studies since most of the studies are performed on adults being treated by a combination of orthodontics and orthognatic surgery (49). According to the available literature, most of the studies seem to agree that adults who need orthognatic treatment, but have not yet started treatment, have worse OHRQoL than a couple of months postsurgery (50–53). Another objective of the present study was to resolve the question whether SE or personality traits can be considered moderators on the association between treatment need and OHRQoL. The Wilson–Cleary model provides a helpful framework for investigating the association between OHRQoL and orthodontic treatment need and the potential moderating role of SE and personality traits (54).
This model states that HRQoL is influenced by several factors: biological variables, symptom status, health functioning, general health perceptions, environmental, and individual factors. In other words, health-related quality-of-life outcomes experienced by a patient are determined not only by the nature and severity of the disease or disorder but also by characteristics of patients and their environment. Most studies investigating OHRQoL have focused on the associations between biological variables and OHRQoL, with little emphasis on the psychological characteristics of orthodontic patients (22). According to the Wilson–Cleary model, psychological factors such as SE and personality traits can be considered potential moderators between orthodontic treatment need and OHRQoL. This could not be proven in this study. In the past, however, it was demonstrated that one’s psychological profile can influence the social and emotional impacts of malocclusion (8). It was also found that SE did not play a role as moderator of the association between normative treatment need and OHRQoL in a previous study in children (26). A significant, yet weak to modest, association between SE and OHRQoL can be found in adults, which appears to be rather similar in children (26). Many psychological studies support the belief that SE is a personal resource that facilitates coping with less favourable conditions such as poor dental aesthetics (8, 55). According to the Wilson–Clearly model, SE is considered as a focal aspect of psychological health and higher levels of SE would be related to greater life satisfaction (35, 56). Furthermore, several studies found an association between SE and the way people are satisfied with their facial appearance (57–59). In addition, a significant association can be found between OHRQoL and some personality traits like neuroticism and extraversion. Extraversion can be considered to be a good predictor of positive affect. Neuroticism, on the other hand, can be considered as a good predictor of negative affect. Positive and negative affect are characterized by the frequency and intensity that people experience positive and negative emotions. Neuroticism assesses aspects of vulnerability, anxiety, hostility, and depression, which interferes with the perception on the quality of life in relation to chronic diseases (60, 61). It has been stated that facial attractiveness correlated with extraversion and SE and smile attractiveness correlated with neuroticism and SE (62). As mentioned before, personality characteristics may shape the way an individual reacts to symptoms and thus construct their illness state and, therefore, can be related to one’s OHRQoL (25). It is noteworthy that personality traits apparently also have an influence on a patient’s compliance and willingness to undergo orthodontic treatment (63, 64). Keeping all of this in mind, it may be useful to get insight in someone’s personality traits. The association between SE and the Big Five personality dimensions has been examined often in the past because SE and personality share a common underlying aetiology and are assumed to directly
European Journal of Orthodontics, 2015
Figure 1. Interaction between self-esteem and treatment need (based on Dental Health Component) for the handicap domain of the Oral Health Impact Profile-14 score. DHC, Dental Health Component; OHIP-14, Oral Health Impact Profile-14; Rosenberg, Rosenberg self-esteem scale.
Figure 2. Interaction between neuroticism (norm referenced on gender) and treatment need (based on Dental Health Component) for the total Oral Health Impact Profile-14 (OHIP-14) score. DHC, Dental Health Component.
influence each other. They have found strong negative correlations between SE and neuroticism, moderate positive correlations with extraversion and conscientiousness, and week positive correlations with agreeableness and openness (38). In this study, however, we found significant associations between SE and all the Big Five Personality traits. Weak to strong levels of correlation can be found. The association between SE and neuroticism appears to be the strongest. Some limitations of this study must be considered. Our aim was to investigate the association between orthodontic treatment need and OHRQoL and its potential moderators in a clinical population. The findings of this study cannot uncritically be transferred to the general population. For example, patients seeking orthodontic treatment have more severe malocclusions and worse OHRQoL than those who do not seek orthodontic treatment (45). However, our sample did not differ from the average population with respect to SE and personality traits. This comparison was only to gain a feel of the differences. To determine the need for orthodontic treatment, the IOTN was used, analogue with most other studies concerning OHRQoL (41). One disadvantage of the IOTN is the risk of insensitivity for and misjudgement of the needs of the individual patient. It is hard to pinpoint minor irregularities that a patient is deeply concerned about (65). Therefore, any treatment need assessment should at least allow appropriate weighting of the aesthetic aspect of a malocclusion. The AC of the IOTN has been particularly designed for that purpose (6). Nevertheless, the AC of IOTN still being a clinician-based measure has its limitations as it measures normative rather than perceived treatment need. To overcome these problems, several studies have asked the patients to self-rate their dentition in accordance with the AC of IOTN in order to assess the self-perceived treatment need (7, 66, 67). On the other hand, the concept behind the AC might be difficult to understand and this can lead to a failure in selecting a photograph, which best presents the degree of dental attractiveness. This is the case for specific morphological traits that are not represented
in the scale. Frontal intraoral photographs of the AC are two-dimensional representations of three-dimensional shapes. This might mask problems related to overjet and create a grading scale solely based on the irregularity of their teeth. This makes the self-perceived AC score of the IOTN less suitable for surgical patients (68, 69). Another possible problem is that when orthodontic treatment need is based on the IOTN only, some patients who do not actually have psychosocial need for treatment would be treated (8). A similar study confirms these findings (66). The OHRQoL measure used in this study is the OHIP-14, a widely used generic OHRQoL measure (28). However, the participants of the present study were people wanting more information about orthodontic care. Given this, maybe a more condition specific measure should have been used (70). It was reported that the magnitude of the statistical difference between those with and without treatment need was larger when OHRQoL was assessed using the UK OHRQoL measure compared to OHIP-14 (41). Our present cross-sectional study focused on a clear hypothesis about the moderating role of SE and personality traits on the association between orthodontic treatment need and OHRQoL. The results suggest that orthodontic treatment need, SE, and some personality traits have an influence on OHRQoL. A moderating role cannot be confirmed. Orthodontic treatment need, SE, and personality traits, such as neuroticism and extraversion, seem to be independently related to OHRQoL and can help us understand our patient on a more psychological level and beyond clinician parameters. According to the literature, we expect that the OHRQoL will change during treatment, but the question remains what the influence is of psychological factors such as SE and/or personality traits. Longitudinal research is required to disentangle the role of these factors on the outcome of orthodontic treatment and the use of OHRQoL measures as a justification for orthodontic treatment. Along with other clinical assessments, the use of OHRQoL as an outcome measure can help the clinician in their evaluation of the efficacy of specific treatment protocols from the patients’ perspectives. Furthermore,
M. Clijmans et al. professionals can weigh the risks and benefits associated with treatment more accurately. Moreover, OHRQoL can provide evidence that costs associated with treatment are worth the expense and can help the patient in their decision making (71).
Conclusions The aim of the present study was to investigate whether an association exists between treatment need and OHRQoL in adults who are seeking orthodontic treatment and whether this association is influenced by SE and/or personality traits. The findings can be summarized as follows: 1. A significant, yet modest to weak, association can be found between treatment need and OHRQoL (total OHIP-14 and some domains). One’s OHRQoL is better if treatment need is lower. 2. A significant, yet modest to weak, association exists between SE and the OHRQoL (total OHIP-14 score and all the different domains): the higher the SE, the lower the OHIP-14 score, indicating a better OHRQoL. 3. Significant associations for the total OHIP-14 score as well as some domains and certain personality traits can be found. These correlations are modest to weak. 4. Significant associations can be found between SE and all the Big Five personality traits. Levels of correlation vary from weak to strong. 5. There is no evidence that SE or personality traits moderate the association between OHRQoL and treatment need.
Funding This research received no grant from any funding agency in the public, commercial or not-for-profit sectors.
References 1. Jenny, J. (1975) A social perspective on need and demand for orthodontic treatment. International Dental Journal, 25, 248–256. 2. Grzywacz, I. (2003) The value of the aesthetic component of the Index of Orthodontic Treatment Need in the assessment of subjective orthodontic treatment need. European Orthodontic Society, 25, 57–63. 3. Tsakos, G. (2008) Combining normative and psychosocial perceptions for assessing orthodontic treatment needs. Journal of Dental Education, 72, 876–885. 4. Shaw, W.C. (1981) Factors influencing the desire for orthodontic treatment. European Journal of Orthodontics, 3, 151–162. 5. Shaw, W.C., Addy, M. and Ray, C. (1980) Dental and social effects of malocclusion and effectiveness of orthodontic treatment: a review. Community Dentistry and Oral Epidemiology, 8, 36–45. 6. Brook, P.H. and Shaw, W.C. (1989) The development of an index of orthodontic treatment priority. European Journal of Orthodontics, 11, 309– 320. 7. Kok, Y.V., Mageson, P., Harradine, N.W.T. and Sprod, A.J. (2004) Comparing a quality of life measure and the aesthetic component of the index of orthodontic treatment need (IOTN) in assessing orthodontic treatment need and concern. Journal of Orthodontics, 31, 312–318. 8. Agou, S., Locker, D., Streiner, D.L., and Tompson, B. (2008) Impact of self-esteem on the oral-health-related quality of life of children with malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics, 134, 484–489. 9. World Health Organization (1993) Study protocol for the World Health Organization project to develop a Quality of Life assessment instrument (WHOQOL). Quality of Life Research, 2, 153–159. 10. Hassan, H.A. and Amin, H.S. (2010) Association of orthodontic treatment needs and oral health-related quality of life in young adults. American Journal of Orthodontics and Dentofacial Orthopedics, 137, 42–47.
7 11. Inglehart, M.R. and Bagramian, R.A. (2008) Oral Health-Related Quality of Life. Quintessence Publishing, Surrey, UK. 12. Shaw, W.C., Richmond, S., Kenealy, P.M., Kingdon, A. and Worthington, H. (2007) A 20-year cohort study of health gain from orthodontic treatment: psychological outcome. American Journal of Orthodontics and Dentofacial Orthopedics, 132, 146–157. 13. Tung, A.W. and Kiyak, H.A. (1998) Psychological influences on the timing of orthodontic treatment. American Journal of Orthodontics and Dentofacial Orthopedics, 113, 29–39. 14. Kiyak, H.A. (2008) Does orthodontic treatment affect patients’ quality of life? Journal of Dental Education, 72, 886–894. 15. DiBiase, A.T. and Sandler, P.J. (2001) Malocclusion, orthodontics and bullying. Dental Update, 28, 464–466. 16. Huang, C. (2010) Mean-level change in self-esteem from childhood through adulthood: meta-analysis of longitudinal studies. Review of General Psychology, 14, 251–260. 17. Crocker, J., Thompson, L.L., McGraw, K.M. and Ingerman, C. (1987) Downward comparison, prejudice, and evaluations of others: effects of selfesteem and threat. Journal of Personality and Social Psychology, 52, 907–916. 18. Curbow, B., Somerfield, M., Legro, M. and Sonnega, J. (1990) Self-concept and cancer in adults: theoretical and methodological issues. Social Science and Medicine, 31, 115–128. 19. Flammer, A. (1995) Developmental analysis of control beliefs. In Bandura, A. (ed.), Self-efficacy in Changing Societies. Cambridge University Press, Cambridge, pp. 69–113. 20. Haine, R.A., Ayers, T.S., Sandler, I.N., Wolchik, S.A. and Weyer, J.L. (2003) Locus of control and self-esteem as stress-moderators or stress-mediators in parentally bereaved children. Death Studies, 27, 619–640. 21. Child, I. (1968) Personality in culture. In Borgatta, E.F. and Lambert, W.W. (eds), Handbook of Personality Theory and Research. Rand McNally, Chicago, IL, pp. 82–145. 22. Conley, J.J. (1985) Longitudinal stability of personality traits: a multitraitmultimethod-multioccasion analysis. Journal of Personality and Social Psychology, 94, 1266–1288. 23. Agou, S., Locker, D., Muirhead, V., Tompson, B. and Streiner, D.L. (2011) Does psychological well-being influence oral-health-related quality of life reports in children receiving orthodontic treatment? American Journal of Orthodontics and Dentofacial Orthopedics, 139, 369–377. 24. McCrae, R.R. and Costa, P. (1990) Personality in Adulthood. The Guilford Press, New York, USA. 25. Thomson, W.M., Caspi, A., Poulton, R., Moffit, T.E. and Broadbent, J.M. (2011) Personality and oral health. European Journal of Oral Sciences, 119, 366–372. 26. De Baets, E., Lambrechts, H., Lemiere, J., Diya, L. and Willems, G. (2012) Impact of self-esteem on the relationship between orthodontic treatment need and oral health-related quality of life in 11- to 16-year-old children. European Journal of Orthodontics, 34, 731–737. 27. Brosens, V., Ghijselings, I., Lemiere, J., Fieuws, S., Clijmans, M. and Willems, G. (2014) Changes in oral health-related quality of life reports in children during orthodontic treatment and the possible role of selfesteem: a follow-up study. European Journal of Orthodontics, 36, 186– 191. 28. Silvola, A.S., Rusanen, J., Tolvanen, M., Pirttiniemi, P. and Lahti, S. (2012) Occlusal characteristics and quality of life before and after treatment of severe malocclusion. European Journal of Orthodontics, 34, 704–709. 29. Natrass, C. and Sandy, J.R. (1995) Adult orthodontics—a review. British Journal of Orthodontics, 22, 331–337. 30. Cunningham, S.J. and Hunt, N.P. (2001) Quality of life and its importance in orthodontics. Journal of Orthodontics, 28, 152–158. 31. Slade, G.D. (1997) Derivation and validation of a short-form oral health impact profile. Community Dentistry Oral Epidemiology, 25, 284–290. 32. Slade, G.D. and Spencer, A.J. (1994) Development and evaluation of the Oral Health Impact Profile. Community Dental Health, 11, 3–11. 33. Locker, D. (2004) Oral health and quality of life. Oral Health and Preventive Dentistry, 2, 247–253.
8 34. Van der Meulen, M.J., John, M.T., Naeije, M. and Lobbezoo, F. (2008) The Dutch version of the Oral health Impact Profile (OHIP-NL): translation, reliability, and construct validity. BMC Oral Health, 8, 11. 35. Rosenberg, M. (1965) Society and the Adolescent Self-image. Princeton University Press, Princeton, NJ. 36. Hashem, A., Kelly, A., O’Connell, B. and O’Sullivan, M. (2013) Impact of moderate and severe hypodontia and amelogenesis imperfecta on quality of life and self-esteem of adult patients. Journal of Dentistry, 41, 689–694. 37. Schmitt, D.P. and Allik, J. (2005). Simultaneous administration of the Rosenberg Self-Esteem Scale in 53 nations: exploring the universal and culture-specific features of global self-esteem. Journal of Personality and Social Psychology, 89, 623–642. 38. Franck, E., De Raedt, R., Barbez, C. and Rosseel, Y. (2008) Psychometric properties of the Dutch Rosenberg Self-Esteem Scale. Psychologica Belgica, 48, 25–35. 39. Costa, P.T., Jr and McCrae, R.R. (1992) Revised NEO Personality Inventory (NEO-PI-R) and the Five Factor Inventory (NEO-FFI): Professional Manual. Psychological Assessment Resources Inc., Odessa, FL. 40. Hoekstra, H.A. and De Fruyt, F. (1999) Bevolkingsnormen NEO-PI-R persoonlijkheidsvragenlijst. Swets Test Publishers, Lisse, The Netherlands. 41. Liu, Z., McGrath, C. and Hägg, U. (2009) The impact of malocclusion/ orthodontic treatment need on the quality of life. A systematic review. Angle Orthodontist, 79, 585–591. 42. O’Brien, C., Benson, P.E. and Marshman, Z. (2007) Evaluation of a quality of life measure for children with malocclusion. Journal of Orthodontics, 34, 185–193. 43. Spalj, S., Slaj, M., Varga, S., Strujic, M. and Slaj, M. (2010) Perception of orthodontic treatment need in children and adolescents. European Journal of Orthodontics, 32, 387–394. 44. O’Brien, K., Wright, J.L., Conboy, F., Macfarlane, T. and Mandall, N. (2006) The child perception questionnaire is valid for malocclusions in the United Kingdom. American Journal of Orthodontics and Dentofacial Orthopedics, 129, 536–540. 45. Feu, D., de Oliveira, B.H., de Oliveira Almeida, M.A., Kiyak, H.A. and Miguel, J.A. (2010) Oral health-related quality of life and orthodontic treatment seeking. American Journal of Orthodontics and Dentofacial Orthopedics, 138, 152–159. 46. Liu, Z., McGrath, C. and Hägg, U. (2011) Associations between orthodontic treatment need and oral health-related quality of life among young adults: does it depend on how you assess them? Community Dentistry and Oral Epidemiology, 39, 137–144. 47. Rusanen, J., Lahti, S., Tolvanen, M. and Pirttiniemi, P. (2010) Quality of life in patients with severe malocclusion before treatment. European Journal of Orthodontics, 32, 43–48. 48. Masood, Y., Masood, M., Zainul, N.N., Araby, N.B., Hussain, S.F. and Newton, T. (2013) Impact of malocclusion on oral health related quality of life in young people. Health and Quality of Life Outcomes, 11, 25. 49. Azuma, S.H., Kohzuiki, M., Saeki, S.H., Tajima, M., Igrashi, K. and Sugawara, J. (2008) Beneficial effects of orthodontic treatment on quality of life in patients with malocclusion. The Tohoku Journal of Experimental Medicine, 214, 39–50. 50. Esperão, P.T., de Oliveira, B.H., de Oliveira Almeida, M.A., Kiyak, H.A. and Miguel, J.A. (2010) Oral health-related quality of life in orthognathic surgery patients. American Journal of Orthodontics and Dentofacial Orthopedics, 137, 790–795. 51. Lee, S., McGrath, C. and Samman, N. (2008) Impact of orthognathic surgery on quality of life. Journal of Oral and Maxillofacial Surgery, 66, 1194–1199. 52. Choi, W.S., Lee, S., McGrath, C. and Samman, N. (2010) Change in quality of life after combined orthodontic-surgical treatment of dentofacial
European Journal of Orthodontics, 2015 deformities. Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 109, 46–51. 53. Hunt, O.T., Johnston, C.D., Hepper, P.G. and Burden, D.J. (2001) The psychosocial impact of orthognathic surgery: a systematic review. American Journal of Orthodontics and Dentofacial Orthopedics, 120, 490–497. 54. Wilson, I.B. and Cleary, P.D. (1995) Linking clinical variables with healthrelated quality of life. A conceptual model of patient outcomes. JAMA, 273, 59–65. 55. Harter, S. (1992) Visions of self: beyond the me in the mirror. Nebraska Symposium on Motivation, 40, 99–144. 56. Lachman, M.E. and Weaver, S.L. (1998) The sense of control as a moderator of social class differences in health and well-being. Journal of Personality and Social Psychology, 74, 763–773. 57. Berscheid, E., Walster, E. and Bohrnstedt, G. (1973) Body image. Psychology Today, 7, 119–131. 58. McDonald, P.J. and Eilenfield, V.C. (1980) Physical attractiveness and the approach/avoidance of self-awareness. Personality and Social Psychology Bulletin, 6, 391–395. 59. Albino, J.E., Tedesco, L.A. and Kiyak, H.A. (1990) Esthetic issues in behavioral dentistry. Annals of Behavioral Medicine, 12, 148–155. 60. Silva, I.B. and Nakano, T.C. (2011) Big Five factor model: research analysis. Avaliaçao Psicological, 10, 51–62. 61. Nunes, C.H.S.S., Hutz, C.S. and Giacomoni, C.H. (2009) Relationship between subjective well-being and personality within the Big Five personality model. Avaliacao Psicological, 8, 99–108. 62. Van der Geld, P., Oosterveld, P., Van Heck, G. and Kuijpers-Jagtman, A.M. (2007) Smile attractiveness. Self-perception and influence on personality. Angle Orthodontist, 77, 759–765. 63. Umaki, T.M., Umaki, M.R. and Cobb, C.M. (2012) The psychology of patient compliance: a focused review of the literature. Journal of Periodontology, 83, 395–400. 64. Hansen, V., Liu, S.S., Schrader, S.M., Dean, J.A. and Stewart, K.T. (2013) Personality traits as a potential predictor of willingness to undergo various orthodontic treatments. Angle Orthodontist, 83, 899–905. 65. Shaw, W.C., Richmond, S. and O’Brien, K.D. (1995) The use of occlusal indices: a European perspective. American Journal of Orthodontics and Dentofacial Orthopedics, 107, 1–10. 66. Ghijselings, I., Brosens, V., Willems, G., Fieuws, S., Clijmans, M. and Lemiere, J. (2014) Normative and self-perceived orthodontic treatment need in 11- to 16-year-old children. European Journal of Orthodontics, 36, 179–185. 67. Mandall, N.A., Wright, J., Conboy, F.M. and O’Brien, K.D. (2001) The relationship between normative orthodontic treatment need and measures of consumer perception. Community Dental Health, 18, 3–6. 68. Livas, C. and Delli, K. (2013) Subjective and objective perception of orthodontic treatment need: a systematic review. European Journal of Orthodontics, 35, 347–353. 69. Johnston, C., Hunt, O., Burden, D., Stevenson, M. and Hepper, P. (2010) Self-perception of dentofacial attractiveness among patients requiring orthognathic surgery. Angle Orthodontist, 80, 361–366. 70. Cunningham, S.J., Garratt, A.M. and Hunt, N.P. (2000) Development of a condition-specific quality of life measure for patients with dentofacial deformity: I. Reliability of the instrument. Community Dentistry and Oral Epidemiology, 28, 195–201. 71. Sischo, L. and Broder, H.L. (2011) Oral health-related quality of life: what, why, how and future implications. Journal of Dental Research, 90, 1264– 1270.