Introduction
The purpose of this study was to investigate the longitudinal psychosocial effects of changes in malocclusion from adolescence to adulthood on oral health–related quality of life (OHRQOL), self-rated dental appearance, and overall life satisfaction.
Methods
The Dunedin Multidisciplinary Health and Development Study is a longitudinal birth cohort study of 1037 children born at Queen Mary Hospital, Dunedin, New Zealand, between April 1, 1972 and March 31, 1973. Data on their health and development, including dental examinations, has since been collected periodically. Malocclusion severity was measured using the Dental Aesthetic Index in participants aged 15 and 45 years (data collected at age 18 years was supplemented for data missing at age 15 years). Other data collected included clinically assessed oral health (dental caries and periodontal disease experience) and self-rated dental appearance, OHRQOL, life satisfaction, and personality traits.
Results
Malocclusion data were available for 868 participants in adolescence and 834 aged 45 years. For those with a severe handicapping malocclusion at 15 years old, 46.6% who received orthodontic treatment transitioned to a resolved (ie, mild-moderate) malocclusion when aged 45 years, whereas only 16.2% of those who did not receive orthodontic treatment made that transition. A transition to a worse malocclusion was associated with impacts on OHRQOL when aged 45 years in the subdomains of functional limitation, psychological discomfort, and physical disability as well as worse self-ratings of dental appearance, and these findings were held after adjusting for potential confounders. Malocclusion was not associated with overall life satisfaction.
Conclusions
Maintenance of acceptable occlusion after orthodontic treatment requires a strong emphasis on achieving and maintaining excellent dental health and avoiding chronic oral conditions such as dental caries and tooth loss. The long-term benefits of orthodontic treatment may diminish by midlife unless good dental health is maintained. Orthodontists have the responsibility to raise awareness among their patients on how to maintain good oral health after orthodontic treatment.
Highlights
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This longitudinal study investigates the association between adolescent malocclusion and adulthood psychosocial outcomes.
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Incident and sustained malocclusion were associated with worse self-rated dental appearance and poor OHRQoL in several subdomains.
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Malocclusion was not associated with overall life satisfaction.
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The long-term benefits of orthodontic treatment may diminish by midlife unless good dental health is maintained.
Physical appearance is a determinant of social acceptance, and dental malocclusions can largely affect how an individual’s physical appearance is perceived, both by themselves and by others. There is low-level evidence that dental malocclusions adversely affect an individual’s psychosocial well-being, but whether these effects last into adulthood is unknown. The long-term psychological benefits of correcting malocclusions are often cited as a rationale for undertaking orthodontic treatment; however, there is a paucity of high-quality evidence to demonstrate the impact of malocclusion over the life course.
A few studies have investigated the effect of malocclusion on oral health–related quality of life (OHRQOL) while controlling for other important covariates, including personality traits and dental health. The current evidence for an association between malocclusion and OHRQOL is mostly based on low-level evidence from cross-sectional studies and cohort studies with short-term follow-up. Furthermore, studies that have investigated this relationship over the long term have failed to maintain a high retention rate.
Further evidence is required from longitudinal cohort studies to understand the association between malocclusion and psychosocial outcomes in adulthood and better understand the long-term impact of malocclusion on adulthood. This study aimed to (1) investigate the association between adolescent malocclusion and quality of life 30 years later and (2) investigate whether changes in malocclusion, or malocclusion transitions, are associated with differences in OHRQOL.
Material and methods
The Dunedin Multidisciplinary Health and Development Study is a longitudinal birth cohort study investigation of 1037 children born at Queen Mary Hospital, Dunedin, New Zealand, between April 1, 1972 and March 31, 1973. A sample of 1037 children form the basis for the longitudinal study and data on their health and development, including dental examinations, has since been collected periodically. Some 938 participants (94.1% of the surviving cohort) took part in the most recent assessment phase, which was conducted when participants were 45 years old. This study used data collected from participants aged 15, 18, and 45 years. Ethical approval for the study was granted by the Otago Research Ethics Committee, and participants gave informed consent before participating.
The Dental Aesthetic Index (DAI) is an epidemiologic instrument that provides a measure of malocclusion on the basis of 10 weighted occlusal traits. These traits include a count of missing premolars and anterior teeth, anterior crowding and spacing, midline diastema, maxillary and mandibular overjet, anterior open bite, maxillary and mandibular incisor irregularity, and molar relationship. , The DAI was recorded by trained and calibrated examiners when participants were aged 15, 18, and 45 years. , These analyses use DAI data from participants aged 15 and 45 years; however, for participants who were not orthodontically examined at 15 years old, we substituted DAI data collected when participants were 18 years old (if data were available). Malocclusion severity can be classified as: normal or minor malocclusion (15-25), definite malocclusion (26-31), severe malocclusion (32-35), or handicapping malocclusion (>36). Malocclusion characteristics were dichotomized to define transition groups from age 15-45 years. Dental malocclusion in participants aged 15 and 45 years was dichotomized so that DAI scores <31 were classified as none-moderate malocclusion, and scores >31 were classified as having a severe handicapping malocclusion. Participants were classified into 4 groups: never (never had a malocclusion at 15 and 45 years old), resolved (resolution of malocclusion between 15 and 45 years old), incident (malocclusion not present at 15 years old but present at 45 years old), and persistent (malocclusion present at both 15 and 45 years old).
Participants were asked whether they had received any orthodontic treatment when they were aged 15 and 45 years. This self-reported history of orthodontic treatment included any form of treatment, including removable or fixed appliances, extractions, or orthognathic surgery.
The short-form Oral Health Impact Profile (OHIP-14) was used to assess participants’ OHRQOL at 45 years old. The prevalence of impacts was calculated for each subdomain as the percentage of participants who answered ≥1 item as fairly often or very often for each subdomain and overall. The extent was calculated as the number of items reported fairly often or very often.
Participants were asked to rate their dental appearance at 45 years old using the following questions: (1) How satisfied are you with your smile? and (2) How satisfied are you with the straightness of your teeth? Responses were recorded on a visual analog scale, from 0 (not satisfied) to 10 (very satisfied). These scores were z-standardized for subsequent analyses, with a mean of 0 and a standard deviation of 1.
The Satisfaction With Life Scale items are global, allowing the individual to weigh domains of their lives in terms of their values. The 5 items included: (1) in most ways, my life is close to ideal; (2) the conditions of my life are excellent; (3) I am satisfied with my life; (4) so far, I have gotten the important things I want in life; and (5) if I could live my life over, I would change almost nothing.
The 5 items produce a score ranging 5-35. A score of 1-7 is given to each item (1, strongly disagree; 2, disagree; 3, slightly disagree; 4, neither agree nor disagree; 5, slightly agree; 6, agree; and 7, strongly agree). Therefore, for this analysis, the life satisfaction scores were z-standardized.
A number of potential confounders and covariates were included in the analysis. These included count of decayed, missing, and filled teeth (DMFS score), periodontal disease (percentage of sites with >5 mm of attachment loss), personality traits (multidimensional personality questionnaire), childhood and adulthood socioeconomic status (SES; Elley-Irving Scale and New Zealand Socioeconomic Index), and sex. A detailed description of each of these variables is included as an Appendix in Elley and Irving.
Statistical analysis
The statistical significance of differences in categorical variables was tested with chi-square and Fisher exact tests, as appropriate. Correlations between nonnormally distributed continuous variables were assessed using a Spearman correlation test. Ordinary least squares regression was used to model normally distributed outcomes such as smile satisfaction. Negative binomial regression was used to model the risk for impacts on OHRQOL when aged 45 years by malocclusion trajectories. Logistic regression was used to model binary categorical outcomes, such as the prevalence of impacts on OHRQOL, and adjust for confounders. Adjusted models accounted for potential confounding by sex, personality (z-standardized Multidimensional Personality Questionnaire super factors), SES (trichotomised), DMFS (continuous), and extent of periodontal disease (% sites with >5 mm of periodontal attachment loss).
The association between malocclusion severity at 15 and 45 years old and life satisfaction at 45 years old was assessed using linear regression modeling. Linear regression modeling was used to estimate the unadjusted and adjusted coefficient for z-standardized Diener Life Satisfaction, with a 95% confidence interval. The regression model included sex, Multidimensional Personality Questionnaire superfactors (z-standardized), SES (categorical), DMFS (continuous), and ≥1 site with >5 mm of periodontal attachment loss at 38 years old (dichotomous variable). All statistical analyses were conducted using Stata software (version 15.1; Stata Corp, College Station, Tex).
Results
Malocclusion data were available for 868 participants in adolescence and 834 at age 45 years (92.5% and 88.9% of the surviving cohort, respectively). Most DAI scores included in the adolescent dataset were aged 15 years (n = 781; 90.7%), whereas DAI scores recorded at 18 years old were substituted for 87 participants who had not had a DAI score recorded at 15 years old. During adolescence, the proportion of participants who were affected by malocclusion differed little by sex and SES ( Table I ). Approximately 1 in 10 were affected by a handicapping malocclusion, but that proportion doubled (22.9%) by 45 years old. Socioeconomic inequality in malocclusion became evident by 45 years old. The proportion of low SES participants who were affected by a handicapping malocclusion (41.3%) was 3 times greater than among participants of high SES (13.6%). On average, malocclusion worsened between adolescence and adulthood, with a mean (± standard deviation) DAI score of 27.0 ± 6.5 during adolescence, rising to 31.2 ± 9.2 by age 45 years.
| Variables | Mild (DAI <25) | Moderate (DAI 26-30) | Severe (DAI 31-35) | Handicapping (DAI >36) | Not examined |
|---|---|---|---|---|---|
| Adolescent malocclusion (15 years old) | |||||
| Sex | |||||
| Female | 178 (42.2) | 162 (38.4) | 51 (12.1) | 31 (7.4) | 80 |
| Male | 160 (35.9) | 165 (37.0) | 70 (15.7) | 51 (11.4) | 89 |
| Childhood SES † | |||||
| Low | 74 (46.0) | 58 (36.0) | 21 (13.0) | 8 (5.0) | 54 |
| Medium | 196 (34.8) | 227 (40.3) | 79 (14.0) | 62 (11.0) | 85 |
| High | 65 (46.8) | 41 (29.5) | 21 (15.1) | 12 (8.6) | 28 |
| SES at 45 years old ‡ | |||||
| Low | 59 (38.8) | 56 (36.8) | 26 (17.1) | 11 (7.2) | 39 |
| Medium | 149 (39.2) | 143 (37.6) | 47 (12.4) | 41 (10.8) | 53 |
| High | 110 (38.2) | 114 (39.6) | 36 (12.5) | 28 (9.7) | 23 |
| Overall | 338 (38.9) | 327 (37.7) | 121 (13.9) | 82 (9.5) | 169 |
| Adulthood malocclusion (45 years old) | |||||
| Sex | |||||
| Female | 100 (24.2) | 150 (36.3) | 72 (17.4) | 91 (22.0) | 89 |
| Male | 89 (21.1) | 140 (33.3) | 92 (21.9) | 100 (23.8) | 114 |
| Childhood SES § | |||||
| Low | 32 (21.6) | 47 (31.8) | 28 (18.9) | 41 (27.7) | 67 |
| Medium | 116 (21.4) | 185 (34.2) | 106 (19.6) | 134 (24.8) | 108 |
| High | 41 (29.3) | 57 (40.7) | 28 (20.0) | 14 (10.0) | 27 |
| SES at 45 years old ⁋ | |||||
| Low | 18 (12.0) | 44 (29.3) | 26 (17.3) | 62 (41.3) | 41 |
| Medium | 86 (21.6) | 148 (37.2) | 74 (18.6) | 90 (22.6) | 35 |
| High | 85 (29.7) | 98 (34.3) | 64 (22.4) | 39 (13.6) | 25 |
| Overall | 189 (22.7) | 290 (34.8) | 164 (19.7) | 191 (22.9) | 203 |
† Childhood SES data were missing for 4 participants who had malocclusion data at 15 years old
‡ Adulthood SES data were missing for 14 participants who had malocclusion data at 15 years old.
§ Childhood SES data were missing for 5 participants who had malocclusion data at 45 years old.
⁋ Adulthood SES data were available for all participants who had malocclusion data at 45 years old.
Orthodontic treatment history data were available for 778 participants aged 15 years. Of these, 7.1% (n = 55) were undergoing orthodontic treatment with fixed appliances at 15 years old assessment, whereas a further 18.8% (n = 146) had previously received such treatment. A further 5.3% (n = 41) were undergoing treatment with a removable appliance, and 6.5% (n = 46) had already completed such treatment.
Orthodontic treatment history data were available for 902 participants aged 45 years. One-third reported they had received orthodontic treatment at some point before age 45 years (n = 310, 34.4%). Of those, 196 (64.3%) reported having “braces,” 141 (46.2%) reported having a “plate,” 10 (3.3%) reported having “jaw surgery,” and 113 (37.1%) reported that they had “extractions” as part of their orthodontic treatment. More females received orthodontic treatment before 15 years old, whereas more males received orthodontic treatment subsequently. By 45 years old, the proportion of males and females who had received orthodontic treatment was similar.
Of those with no-to-mild malocclusion (DAI ≤25) at 15 years old, more than half experienced a transition to a worse malocclusion category by 45 years old. Of those with a handicapping malocclusion when aged 15 years, more than half (62.1%) still had a handicapping malocclusion when aged 45 years. Half of those who had resolution of their malocclusion between 15-45 years old were of high SES, whereas only 2% were of low SES ( Table II ).
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