Effect of malocclusion on adults seeking orthodontic treatment


Our objective was to examine the Teen Oral Health-related Quality of Life (TOQOL) questionnaire for use in adults receiving orthodontic treatment and assess validity and reliability by age group.


Teenagers from 10 to 18 years and adults 18 and over completed surveys at the orthodontic clinic at Boston University. The survey consisted of sociodemographic information, dental behavior questions, and the TOQOL instrument. Malocclusion severity was assessed using the Index of Orthodontic Treatment Need.


Overall, 161 teens and 146 adults participated. The mean ages were 13 years for the teens and 32 years for the adults. Subjects were represented by both sexes and diverse racial and ethnic backgrounds. In general, scores overall and by domains were higher for adults than for teens, signifying a greater effect of the malocclusion on the quality of life. Mean TOQOL scores as well as emotional and social domain scores ( P <0.001) were worse (17.6) in adults than in teens (11.9; P <0.01). Construct validity was supported by strong a association of TOQOL scores with self-reported oral health. The Cronbach alpha was higher in adults overall and for all domains (0.75 in adults compared with 0.68 in teens).


Adults who come for orthodontic treatment appear to be more affected by their malocclusion than are teens. The total TOQOL score and the emotional and social domains were significantly higher for adults. The total TOQOL score and the emotional and social domains were significantly higher (worse) for adults than teens. This project suggested that TOQOL may be a useful way to measure the impact of malocclusion on the quality of life in both adults and teens.


  • Adults’ quality of life is more affected by malocclusion than teens’.

  • Social and emotional aspects of life are particularly more affected.

  • The TOQOL instrument is a valid and reliable way to measure the impact of malocclusion for both adults and teens.

Oral health-related quality of life is the extent to which oral and perioral conditions affect people’s lives and general health, including diet, speech, and well-being.

Conditions affecting oral health, such as malocclusion, are prevalent in our society. Data from the Third National Health and Nutrition Examination Survey and western European studies suggest that two thirds to three fourths of adults have some form of malocclusion, with consequences for not only physical well-being but also impairment of quality of life by affecting function, appearance, interpersonal relationships, socializing, self-esteem, and psychological well-being. It is not surprising, therefore, that the proportion of adults seeking orthodontic treatment in the United States has increased dramatically in recent decades.

Adults seek orthodontic treatment for a wide variety of reasons including esthetic, social, functional, and psychological concerns. The orofacial region is an important area that draws attention in verbal and nonverbal communication and interpersonal interactions. In today’s society, a person’s dentition is an important component of facial attractiveness, which can markedly affect his or her self-esteem and self-image. In addition, orthodontics may facilitate other dental treatment. Improving these aspects of quality of life is an important reason for undergoing orthodontic treatment. For clinicians, understanding the physical, social, functional, and psychological implications of malocclusion on oral health-related quality of life is important, since it can inform us about the effects of malocclusion on people’s lives and suggest why they seek orthodontic treatment.

Before the 1970s, the patient’s quality of life was not a consideration in dentistry. In 1972, Elwood published one of the first studies that looked at quality of life in relation to old age. This led to an increase in research involving quality of life as it related to various health conditions such as, obesity, respiratory disease, pain, and epilepsy. Since that time, the social impacts of dental disease and the relationship between dental conditions and quality of life have been assessed widely. Several studies have examined quality of life, and oral health-related quality of life and its relationship to oral health. They have generally shown that diminished oral health has a negative impact on quality of life. Fewer studies, though, have examined quality of life and its relationship to malocclusion or, more specifically, the correlations between orthodontic treatment and quality of life.

Few early studies looked specifically at how malocclusion affects quality of life or oral health-related quality of life, or how orthodontic treatment can change these outcomes. Although other research has begun to assess these relationships, the results have been mixed thus far, with some studies reporting that orthodontic treatment did not appear to be associated with oral health-related quality of life. In contrast, a systematic review by Liu et al showed a modest association between malocclusion, orthodontic treatment need, and quality of life. Some weaknesses they noted in the available research were the lack of standardized assessment and a relative weakness in strength of evidence.

Other studies have assessed relationships between the severity of malocclusion, different treatment modalities, and quality of life. Kiyak found evidence that patients’ main motives for seeking orthodontic treatment are esthetic and social concerns. Patients with severe malocclusion appear to have poorer oral health-related quality of life than those with less critical treatment needs in these domains. Furthermore, oral function did not appear to have as great an effect on patients as the severity or visibility of the malocclusion. Orthodontic intervention was found to enhance some aspects of oral health-related quality of life, particularly esthetics, but not necessarily social acceptance.

Other authors have reported that patients with malocclusion may have physical pain as well as psychological discomfort and disability. Patients with malocclusion report feeling self-conscious or tense, have difficulty relaxing, and may be somewhat irritable with other people; they show significant improvements in physical health and mental health quality of life after orthodontic treatment irrespective of the severity of the malocclusion.

More recently, several authors have concluded that malocclusion has a significant negative impact on oral health-related quality of life and its component domains. Patients with high treatment needs and who are more dissatisfied with dental esthetics were more likely to report greater oral effects and a significantly greater negative impact on the overall oral health-related quality of life score. They also found that when orthodontic treatment was completed, oral health-related quality of life increased to levels similar to persons with a normal occlusion.

Zhou et al proposed a modest association between orthodontic treatment and quality of life. The majority of studies they evaluated showed significant correlations between orthodontic treatment and quality of life no matter what measurement was used. Choi et al and Chen et al concluded that malocclusion has a significant negative impact on oral health-related quality of life, especially for the psychological discomfort and psychological disability domains, and can cause limited oral function, pain, and social disability in young adults.

Most studies of adult orthodontic patients relating their malocclusion and oral health-related quality of life found that malocclusion in adults has a remarkable impact on oral health-related quality of life. Patients report lower levels of self-esteem and are self-conscious due to their negative dental esthetic perception and social appearance. Some of the most commonly perceived oral impacts in adults are physical pain as well as psychological discomfort and disability. Once orthodontic treatment finishes, studies have shown that adults reported improvement in disease-specific health-related quality of life, anxiety, esthetic self-perception, and overall improvement in psychological discomfort and disability. However, most research in this area has focused on the impact of orthodontic treatment on the quality of life in children rather than adults. This is in part because children make up the majority of orthodontic patients. However, as more adults seek correction of their malocclusions, investigation into the oral health-related quality of life in adults is important for our understanding of their experience with malocclusion and why they seek treatment.

The aim of this study was to examine the validity and reliability of the Teen Oral Health-related Quality of Life (TOQOL) instrument for adults receiving orthodontic treatment compared with teens. We hypothesized that oral health-related quality of life in adults with malocclusion is worse than that of adults without malocclusion, and that adults with malocclusion who seek orthodontic treatment are more bothered by the malocclusion than are teenagers.

Material and methods

This was a cross-sectional study of adults’ perceptions of the impact of their teeth and mouth on their oral health-related quality of life. The results were compared with data from teenagers seeking orthodontic treatment and from teenagers in the community. In addition to the quality of life instrument, both adult and teenaged patients were asked to rate the esthetic appearance of their teeth relative to the Aesthetic Component of the Index of Orthodontic Treatment Need (IOTN). This project was approved by the Institutional Review Board at Boston University. All participants gave written informed consent.

The patients selected for this study were adults aged 18 years or older who were judged to fall into the grade 2 or greater (worse) category of the Dental Component of the IOTN. Patients with mental or physical disabilities were excluded from the study.

All patients who satisfied the inclusion criteria and were seeking comprehensive or limited orthodontic treatment were invited to participate.

The primary outcomes of interest were overall oral health-related quality of life as related to the patients’ malocclusion. The oral health-related quality of life was measured using the TOQOL, developed by Wright et al, who demonstrated its validity and reliability in a diverse sample of 13- to 18-year-old adolescents. The TOQOL assesses oral health-related quality of life in 5 domains: role, oral health, social, emotional, and physical. Each item in each domain is explored by asking a question beginning, “Due to problems with your teeth and mouth, how often in the past 3 months have you…?” The role domain assesses how the state of the patients’ oral condition impacts their ability to pay attention at school or work, missing work or school, and their ability to sleep. The oral health domain assesses bad breath, bleeding gums, food caught between teeth, and mouth sores. The social domain assesses the impact of the patients’ current oral state on social pressures and interactions, such as worrying about opinions of others in regard to their appearance and comfort with smiling. The emotional domain assesses whether their oral health upsets or worries them, and the physical domain measures difficulty eating and oral pain. For each item, the respondents are asked how often they are bothered and how severely they are bothered.

Patients who came to the orthodontic clinic for treatment were screened preliminarily for eligibility based on initial records. If they qualified based on their IOTN, they were asked to participate at their next appointment before appliances were placed. At that time, those who consented were asked to complete the TOQOL. An oral health screening form was also completed at this time by the principal investigator. This form was used to assess the current oral health status of the participants. Data from the surveys and screening forms were then compiled and analyzed. At the completion of orthodontic treatment, participants will be surveyed again to assess changes in quality of life and oral health-related quality of life.

Questions were asked in 2 parts, and the impact was calculated by a scoring program. The first part of the question asked how often the patients’ oral health bothered them, and the second asked how severely they were bothered. Numeric values were assigned to every possible response as follows: 0, did not happen; 1, once in a while; 2, some of the time; and 3, all the time. Severity values were 0, did not happen; 1, never bothered; 2, bothered a little bit; 3, somewhat bothered; and 4, very bothered.

Scoring was done in the manner of Wright et al. An impact score was created by multiplying the frequency scores by the bother score; impact scores thus ranged from 0 to 12. The impact scores were recoded on a scale of 1 to 13 by adding 1 to each score; missing values were coded as zero. Means and sums were calculated for each domain and for the overall instrument. The overall score was calculated as the sum of the impact values, minus the number of items, divided by the maximum value of an item times the number of items, minus the number of items, times 100.

The Dental Component of the IOTN (completed by the principal investigator) consists of a classification system from grades 1 to 5, with grade 1 indicating no treatment need up to grade 5 indicating great treatment need. The Dental Component was used to assess the presence and severity of malocclusion, and hence orthodontic treatment need. The numbers of decayed, missing, or filled teeth were also assessed from patient records. The Aesthetic Component of the IOTN consists of a visual classification system from grade 1 to 10 using a series of photos, with grade 1 indicating mild esthetic concerns and grade 10 major esthetic concerns. The patient was asked to score the severity of the malocclusion by selecting the photo that looked the most like his or her mouth from the IOTN picture format.

In addition, other potential confounding factors were assessed: age, insurance status, education, and oral health.

Statistical analysis

Data from the survey were double entered into a database, cleaned, and analyzed using software (version 9.3; SAS, Cary, NC). The characteristics of the sample population were described with respect to age, sex, race and ethnicity, insurance, education, and treatment need. TOQOL scores for adults seeking orthodontic treatment were computed overall and by individual domains, and were compared with scores of teenagers undergoing and not undergoing orthodontic treatment from previous studies using t tests and chi-square tests. Additionally, TOQOL scores by groups were obtained using generalized linear modeling.

Simple and multiple linear regressions examined the relationships between TOQOL as the dependent variable and IOTN scores, after adjusting for other covariates. As a test of construct validity, the TOQOL scores were compared across IOTN groups and self-reported oral health. In addition, discriminant validity was estimated by comparing teens and adults needing orthodontic treatment with data on teens surveyed in the schools. Cronbach’s alpha was computed overall and for each domain of the TOQOL for adults and teenagers to examine the reliability (internal consistency) of the instrument. Finally, a 3-way comparison of TOQOL scores among adult orthodontic, teen orthodontic, and teen control groups was done using generalized linear modeling, adjusting for age, IOTN, race, and sex.


A total of 307 subjects participated in this study: 146 adults who were recruited and 161 teens from a previous study. Subjects in both groups represented diverse racial and ethnic backgrounds. In both groups, white subjects represented the greatest proportion of the sample followed by Hispanics/Latinos. Demographic characteristics of the sample are shown in Table I .

Table I
Label Category Adult Teen orthodontics P Teen control
n 307 146 161 303
Mean age (y) 32.45 13.04 <0.001 15.1
Sex Female 63.01% 47.83% 0.008 54.13%
Male 36.99% 52.17% 45.87%
Dental insurance Medicaid 15.49% 47.47% <0.001 57.64%
None 29.58% 6.96% 8.33%
Other 12.68% 3.80% 0.00%
Private 42.25% 41.77% 34.03%
Race group Asian 16.90% 5.16% 0.002 4.01%
Black/African-American 15.49% 18.71% 32.11%
Hispanic/Latino 28.87% 26.45% 22.74%
White/Caucasian 34.51% 36.13% 40.13%
Other/mixed 4.23% 13.55% 1%
Overall health group Excellent/very good/good 97.93% 94.41% 0.113
Fair/poor 2.07% 5.59%
Health of teeth/mouth group Excellent/very good/good 69.86% 78.26% 0.093 85.71%
Fair/poor 30.14% 21.74% 14.29%
Health of teeth/mouth compared to 1 year ago Better/same 90.28% 96.88% 0.018 94.67%
Worse 9.72% 3.13% 5.33%
Teeth (n) 27.24 26.71 0.072 27.68
Aesthetic Component of IOTN 3.54 4.43 0.002
IOTN index 3.34 3.24 0.34
IOTN group 2,3 65.07% 57.76% 0.19
4,5 34.93% 42.24%

Most patients (97%) reported that their general health was excellent, very good, or good. The distribution by age group showed similar findings: 98% of adults and 94% of teens reported excellent, very good, or good overall health.

In regard to their self-rated oral health, fewer (74%) reported excellent, very good, or good health, whereas the remaining (26%) reported fair or poor oral health. The distribution by age showed that 70% of adults reported excellent, very good, or good oral health, and 78% of teens reported excellent, very good, or good.

With respect to dental insurance, in the teen group, 47% of the sample were on Medicaid, followed by 42% with private insurance; 11% responded “none” or “other.” This was different from the adult group, where 42% of the sample had private insurance, followed by none or other at 42%, and Medicaid at 15%. The differences in terms of insurance were statistically significant with a P value <0.001.

The IOTN was divided by group as shown in Table I . The group of teen patients with IOTN scores of 2 or 3 represented 58% of the sample as compared to 65% of the adult group. The mean esthetic component scores were 4.43 in teens and 3.54 in adults. The difference was statistically significant ( P = 0.002).

In general, scores overall and by domains were higher for adults than for teens, signifying greater effects of oral conditions on the quality of life, as seen in Table II . The mean overall TOQOL scores (17 items) were worse (17.5) in adults than in teens (11.9; P <0.01); emotional domain scores were 16.5 in adults vs 9.4 in teens ( P <0.01), and the social domain scores were 35.3 for adults vs 21.6 for teens ( P <0.01). The oral, physical, and role domains were also worse in adults, but the differences were not statistically significant.

Table II
Scores for the domains in the teen and adult groups
Mean (SD) Range Mean scores and impacts % yes
Adult Teen P Adult Teen P
TOQOL score (17 items) 14.59 (11.86) 0-65.69 17.55 11.92 <0.001
Emotional domain 12.78 (18.48) 0-100 16.55 9.4 <0.001
Oral problems 13.11 (12.71) 0-62.5 14.61 11.75 0.054
Physical domain 11.16 (16.02) 0-100 12.49 9.97 0.174
Role domain 3.78 (7.85) 0-66.67 3.85 3.72 0.886
Social domain 28.09 (25.60) 0-100 35.3 21.6 <0.001
Emotional domain
Impact depressed 0.88 (2.05) 0-12 1.2 0.59 0.01 31.94% 14.91% 0.001
Impact feel angry/upset 1.64 (2.70) 0-12 2.06 1.27 0.012 47.89% 34.78% 0.021
Impact feel worried 2.07 (2.94) 0-12 2.71 1.5 <0.001 65.03% 45.91% <0.001
Oral health domain
Impact bad breath 1.26 (2.06) 0-12 1.17 1.34 0.461 35.42% 52.17% 0.003
Impact bleeding gums 1.45 (2.40) 0-12 1.73 1.2 0.056 46.90% 44.72% 0.703
Impact food between teeth 2.79 (2.93) 0-12 3.23 2.39 0.014 78.62% 86.25% 0.079
Impact mouth sores 0.80 (1.44) 0-8 0.88 0.72 0.341 32.41% 33.33% 0.865
Physical domain
Impact difficult eating food like 1.08 (2.25) 0-12 1.33 0.86 0.074 33.79% 25.63% 0.118
Impact trouble eating hot/cold/hard 1.58 (2.52) 0-12 1.73 1.44 0.32 43.75% 41.61% 0.707
Impact pain 1.35 (2.09) 0-12 1.44 1.27 0.465 40.97% 45.96% 0.38
Role domain
Impact hard to pay attention 0.41 (1.26) 0-12 0.56 0.27 0.054 21.38% 10.56% 0.009
Impact miss school/work 0.48 (1.25) 0-8 0.38 0.58 0.158 11.89% 30.63% <0.001
Impact trouble sleeping 0.46 (1.42) 0-12 0.43 0.48 0.742 15.28% 16.77% 0.723
Social domain
Impact crocked teeth/spaces 5.14 (4.27) 0-12 5.83 4.53 0.008 79.02% 86.96% 0.065
Impact worried less attractive 2.78 (3.61) 0-12 3.93 1.76 <0.001 72.22% 46.58% <0.001
Impact not want to smile/laugh 2.59 (3.55) 0-12 3.34 1.91 <0.001 61.11% 47.83% 0.02
Impact unhappy with looks 3.00 (3.46) 0-12 3.94 2.16 <0.001 79.86% 54.66% <0.001
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Dec 12, 2018 | Posted by in Orthodontics | Comments Off on Effect of malocclusion on adults seeking orthodontic treatment
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