Studies in the dental literature do not yet provide conclusive evidence for the functional and psychosocial benefits of orthodontic treatment. In this cross-sectional study, we aimed to assess the oral health-related quality of life of young Brazilian adults, aged 18 to 30 years, who had completed orthodontic treatment compared with untreated subjects waiting for treatment.
The subjects were recruited at a state-funded university clinic. The sample comprised 100 patients in the retention phase of orthodontic treatment for more than 6 months (treated group) and 100 persons who were seeking orthodontic treatment and were still on a waiting list (nontreated group). Data were collected by using the oral health impact profile, the index of orthodontic treatment need (malocclusion severity and esthetic impairment), the Brazilian economic classification criteria (socioeconomic status), and the index of decayed, missing, and filled teeth (oral health status). Statistical analyses were performed by using chi-square and Fisher exact tests and negative binomial regression.
The mean oral health impact profile scores were 3.1 (SD ± 2.99) and 15.1 (SD ± 8.02) in the treated and nontreated groups, respectively. The most frequent impacts in the treated and nontreated groups were “painful aching” and “been self-conscious,” respectively. Comparisons between the groups were controlled for malocclusion severity, clinician-assessed esthetic impairment, age, sex, socioeconomic status, and oral health status. Nontreated young adults had mean oral health impact profile scores 5.3 times higher than did the treated subjects.
Young Brazilian adults who received orthodontic treatment had significantly better oral health-related quality of life scores in the retention phase, after treatment completion, than did nontreated subjects.
Why do patients search for orthodontic treatment? In the early 1980s, it was thought that orthodontic treatment was important because regular dental arches might facilitate oral hygiene, thus reducing the incidences of dental caries and periodontal disease. Also, it was believed that better occlusal contacts could help prevent temporomandibular joint disorders; however, studies have failed to provide solid evidence to support these claims.
Because the smile is the second most observed facial characteristic relating to physical attractiveness, psychosocial research suggests that malocclusion might negatively interfere with self-satisfaction concerning appearance and, accordingly, impair social functioning. Not surprisingly, it seems that the main reason to have orthodontic treatment is to obtain improvement in esthetics and subsequent enhancement of psychosocial well-being that might contribute to a better quality of life.
Previous research findings have shown that malocclusion perceptions differ between professionals and patients, and that self-perceived oral health-related quality of life is not always a reflection of malocclusion severity (ie, some people with severe malocclusions do not report a negative impact on quality of life, whereas others with minor irregularities report high negative impacts on quality of life). Therefore, oral health-related quality of life assessments in orthodontics are imperative to the study of treatment needs, therapy effectiveness, and understanding of patients’ expectations. These patient-centered measures might help with determining the outcomes of orthodontic care.
A systematic review of 23 articles indicated a modest association between malocclusion and the need for orthodontic treatment with quality of life. Although studies generally observed an association, the strength of evidence was relatively low, and the methods were not standardized. Most research in this area has focused on children rather than adults. Because only 5 articles described findings in adults, this systematic review showed a need for further studies with standardized assessment methods, such as the oral health impact profile, originally developed by Slade and Spencer with 49 questions and further reduced to 14 questions, to evaluate the effects of orthodontic treatment on adults’ quality of life.
The few studies focused on adults suggest that dental esthetics have a direct effect on all oral health-related quality of life values. The available data are mostly cross-sectional. Klages et al analyzed the effect of dental esthetics on the oral health-related quality of life of 148 German university students (ages, 18-30 years) by using the aesthetic component of the index of orthodontic treatment need. Their results suggested that even minor irregularities in dental esthetics might have a considerable impact on oral health-related quality of life on the scales of “social appearance concern,” “appearance disapproval,” and “dentally related self-confidence.”
Klages et al investigated the impact of orthodontic treatment history on oral health attitudes in 298 young German adults (ages, 18-30 years) with varying dental esthetics and education levels. The results showed that subjects with favorable dental esthetics and previous orthodontic treatment reported better oral hygiene and self-perceived oral health. Bernabé and Flores-Mir evaluated the influence of anterior occlusal characteristics on self-perceived dental appearance in 267 young Peruvian adults (ages, 16-25 years) using a visual analog scale. They found that the most negative influences were from anterior maxillary spacing, incisal irregularity, and missing anterior teeth.
Hassan and Amin evaluated the effect of orthodontic treatment need on oral health-related quality of life in 366 young Arab adults using the index of orthodontic treatment need and the shortened version of oral health impact profile questionnaire. Treatment need significantly affected mouth aching, self-consciousness, tension, embarrassment, irritability, and life satisfaction.
Chen et al followed longitudinally the changes in oral health-related quality of life during fixed orthodontic appliance therapy in 250 Chinese patients. The patients’ oral health-related quality of life was better after treatment than before or during it.
One important question that has yet to be answered satisfactorily is the duration of quality of life improvements after therapy.
The aim of this cross-sectional study was to assess oral health-related quality of life in young Brazilian adults aged 18 to 30 years, comparing untreated subjects with patients who completed orthodontic treatment at least 6 months before the start of the study. The influences of dental health status, esthetic impairment, malocclusion severity, and sociodemographic characteristics on the patients’ oral health-related quality of life were also examined.
Material and methods
The ethics research committee of the State University of Rio de Janeiro approved this study. The participants were informed about the examination procedures and assured of the confidentiality of the collected information. Only those who gave consent were included in the research.
All subjects were recruited from May to September 2009 at the orthodontic clinic of the Faculty of Dentistry, State University of Rio de Janeiro, which is publicly funded by the state of Rio de Janeiro. The sample comprised 200 young adults (ages, 18-30 years) divided into 2 groups: the treated group and the nontreated group. The treated group consisted of 100 consecutive patients who concluded their orthodontic treatment at the university at least 6 months before the study. The patients in this group were contacted at their retention maintenance appointments. These appointments are routinely scheduled every 6 months for all retention patients at the university clinic. The nontreated group included 100 subjects seeking orthodontic treatment but had yet to start it. They were selected consecutively from a waiting list, according to the following inclusion criteria: age between 18 and 30 years, no craniofacial anomalies (eg, cleft lip or palate), and no previous orthodontic therapy. All participants filled out a consent form and were assured that the data collected would be used for research purposes only. It was explained to the patients in the nontreated group that their answers to the interviews would not be considered in the admission process at the university clinic.
Data were collected through face-to-face interviews, self-completed questionnaires, and oral examinations performed by a trained orthodontist (N.B.P.) at the same orthodontic clinic. For the oral health-related quality of life assessment, the Brazilian version of the oral health impact profile (short form) questionnaire, which has shown good psychometric properties, similar to those from the original instrument, was used.
The examiner read the oral health impact profile questions and the 5 answer options on the Likert scale (never, hardly ever, occasionally, fairly often, and very often), and the subject being interviewed selected and filled in his or her answer on the questionnaire. The interview was performed before the clinical examination, reducing the risk of the influence of buccal and occlusal conditions. During the interview, the examiner registered age, sex, and socioeconomic status using the Brazilian economic classification criteria. This measurement categorizes people into 5 socioeconomic categories (A and B, high socioeconomic status; C, medium socioeconomic status; D and E, low socioeconomic status) by the level of education of the head of the family, consumer goods owned, and housekeeper access.
The clinical examination used the index of orthodontic treatment need, the most used indicator in the literature and one that has been used in studies with young adults to evaluate malocclusion severity (dental health component) and esthetic impairment (aesthetic component). The aesthetic component records any esthetic impairment through a 10-point photograph scale with progressive degrees of esthetic problems, ranging from 1 to 10. The dental health component is a 5-grade index that records treatment need. These 2 scores determine the categories of need: no or little need (dental health component score, 1 or 2; aesthetic component score, 1-4); borderline need (dental health component score, 3; aesthetic component score, 5-7), and need (dental health component score, 4 or 5; aesthetic component score, 8-10). For the treated group, the examiner recorded the dental health component score from the initial casts, before any orthodontic treatment. For the nontreated group, the dental health component was assessed clinically. In the treated group, the normative aesthetic component was determined by analyzing the patient’s photographs and dental cast models obtained just before orthodontic treatment. In the nontreated group, the aesthetic component was determined by clinical examination of the patients. In both groups, only the normative aesthetic scores were assessed because data on the self-perceived aesthetic component were not collected from subjects in the treated group before their treatment. The index of decayed, missing, and filled teeth was used to assess dental health status at the interviews in both groups; the scores were obtained through oral examinations.
The examiner was trained by a gold-standard researcher with broad experience with the index of orthodontic treatment need (J.A.M.). The calibration was done through comparison of the results from 20 plaster casts by the examiner and the gold-standard researcher. To calculate intraexaminer reliability, 20 subjects from the sample were examined twice, with an interval of 10 days.
Descriptive data were presented in univariate tables and evaluated with the chi-square test and the Fisher exact test when appropriate. The comparisons between the treated and nontreated groups were performed by using negative binomial regression, since there was evidence of overdispersion of the main outcome variable: the oral health impact profile (short form) scores. Negative binomial models are an alternative to Poisson models for counting data with overdispersion. In our study, the variance was 8.3 times greater than predicted in the crude model (the likelihood ratio test for the dispersion parameter was P <0.01). Not taking into account overdispersion might lead to underestimation of standard errors, thus producing spurious significant associations.
Negative binomial models produce mean ratios with exponentiated coefficients. Thus, the model presented the crude and adjusted mean ratios of the oral health impact profile scores between the treated and nontreated groups. The covariates used included the index of orthodontic treatment need-dental health component; sex; the baseline normative aesthetic component; the index of decayed, missing, and filled teeth; and economic class. The final model was built by using step-wise backward models with the probability of removal of P >0.20.
Kappa statistics were used to assess intraexaminer reliability and the consistency between the examiner’s scores and the gold-standard scores.
For the oral health impact profile analysis, each answer received a score from 0 for “never” to 4 for “very often,” and the sum of the 14 answers resulted in an overall score from 0 to 56. A higher score indicated poorer oral health-related quality of life. Intraclass correlation coefficients and the Cronbach α were used to assess the stability and internal consistency of the oral health impact profile, respectively. All analyses were performed with Stata software (version 11.2; StataCorp, College Station, Tex).
The examiner demonstrated good agreement with the gold standard for both the index of orthodontic treatment need-dental health component (kappa, 0.92) and the index of orthodontic treatment need-aesthetic component (kappa, 0.93). Intraexaminer reliability was good (kappa, 0.81 for the index of orthodontic treatment need-dental health component [95% CI, 0.79-1.00]; kappa, 0.96 for the index of orthodontic treatment need-aesthetic component [95% CI, 0.90-0.98]), indicating measurement consistency. In regard to internal consistency, the oral health impact profile (short form) instrument had a Cronbach coefficient α of 0.87 (95% CI lower limit, 0.85), and its intraclass correlation coefficient was 0.99 (95% CI, 0.99-0.99), indicating excellent index stability.
The full study sample comprised 200 young adults (63 men, 137 women) aged 18 to 30 years (mean age of the total sample, 22.3 years), divided into 2 groups, with each group comprising 100 subjects: treated and nontreated. No patients were excluded. In the treated group, the mean time after completion of treatment was 3.8 years (SD, ± 2.2 years; minimum, 0.6 year; maximum, 10.5 years).
Descriptive statistics indicated no significant differences between the treated and nontreated groups for the baseline dental health component ( P = 0.09), sex ( P = 0.88), and the mean index of decayed, missing, and filled teeth ( P = 0.57). Statistically significant differences between the treated and nontreated subjects ( P <0.01) were found for mean oral health impact profile (short form) scores, examiner assessed index of orthodontic treatment need-aesthetic component scores, and socioeconomic status ( P <0.01) ( Table I ).
|Total||Treated||Nontreated||P value (chi-square test)|
|Baseline IOTN-DHC ∗|
|No or little need||100||(7)||42.9||(3)||57.1||(4)||0.92|
|Baseline IOTN-AC (normative) ∗|
|No or little need||100||(39)||23.1||(9)||76.9||(30)||<0.01|
|D, E (low)||100||(17)||5.9||(1)||94.1||(16)|
The oral health impact profile scores ranged from 0 to 36. The means and standard deviations were 3.1 (SD ± 2.99) and 15.1 (SD ± 8.02) for the treated and nontreated groups, respectively. Considering the high frequency of “never” responses especially in the treated group, for the purpose of descriptive analysis, the responses of the interviewees to each item of the questionnaire were dichotomized into having (score, >0) and not having (score, 0) an impact. The most frequent impacts in the treated and nontreated groups were “painful aching” and “been self-conscious,” respectively. The frequencies of the positive answers (score, >0) to each item of the oral health impact profile are listed in Table II .
|Groups||Total for each group||Treated group||Nontreated group||P value ∗|
|Oral health impact profile||n||Any impact (n)||Any impact (n)|
|1.Had trouble pronouncing any words||100||7||50||<0.01|
|2. Felt sense of taste has worsened||100||0||5||0.06|
|3. Had painful aching||100||45||78||<0.01|
|4. Found it uncomfortable to eat any foods||100||21||20||1.00|
|5. Been self-conscious||100||37||99||<0.01|
|6. Felt tense||100||34||94||<0.01|
|7. Diet has been unsatisfactory||100||4||89||<0.01|
|8. Had to interrupt meals||100||8||0||0.01|
|9. Found it difficult to relax||100||1||73||<0.01|
|10. Been a bit embarrassed||100||18||82||<0.01|
|11. Been a bit irritable||100||8||7||1.00|
|12. Had difficulty doing usual jobs||100||0||3||0.25|
|13. Felt life less satisfying||100||0||3||0.25|
|14. Been totally unable to function||100||0||1||1.00|