Association between malocclusion and the contextual factors of quality of life and socioeconomic status


The purpose of this study was to examine associations among malocclusion and the contextual factors of quality of life and socioeconomic status.


A cross-sectional study was conducted with a population-based sample of 1256 children from 7 to 10 years old. Malocclusion was assessed clinically; oral health–related quality of life (OHRQoL) was assessed using the Brazilian version of the child perceptions questionnaire; socioeconomic status was determined from data made available by the Research and Planning Institute of Piracicaba, São Paulo, Brazil. Initially, bivariate analyses were performed; after this, starting with variables with P ≤0.20, multilevel multiple logistic regression models were estimated, in which the binomial distribution, function of the logistic connection, and criteria for remaining in the model at P ≤0.05 were considered.


Of the children, 82.1% had some type of malocclusion. Increased age associated with low socioeconomic status was the determinant for occlusal problems. The determination of low OHRQoL appears to be associated with the socioeconomic status in the individual factors, and increased overjet appears to be associated with factors at the contextual level.


Socioeconomic status and age are risk factors for malocclusion. Of the malocclusions evaluated, increased overjet had the most negative influence on the OHRQoL.


  • Malocclusion, quality of life, and socioeconomic status were studied.

  • Socioeconomic status and age were risk factors for malocclusion.

  • Increased overjet had a negative influence on the OHRQoL.

Because malocclusion has a direct effect on the esthetics of the face and smile, an unpleasant appearance may cause people to have difficulties with professional achievement, encourage negative stereotyping, and lead to a negative impact on the quality of life.

The concept of quality of life refers to the feeling of well-being generated by satisfaction or dissatisfaction with life situations considered important to the person. Oral health–related quality of life (OHRQoL) is a term used to evaluate how oral pain or discomfort in physical, psychological, and social functions affects the person’s well-being, and this has been the object of various studies that have related its relationship with malocclusion.

However, most studies that have investigated the impact of malocclusion on quality of life have been conducted in the deciduous dentition or the permanent dentition, and there is a shortage of studies about the influence of occlusal changes on children’s OHRQoL in the mixed dentition. Children begin developing their self-perception about the appearance of their teeth at the stage of mixed dentition, a time of transition during which the greatest and most expressive occlusal changes in occlusal development occur.

At present, the literature has demonstrated the importance of social determinants in health and their influence on oral health and occlusal changes.

Because of the importance of studying the transition from the deciduous to the permanent dentition to better define the time of orthodontic intervention and to determine the distribution of the oral health conditions in populations, the aim of this study was to associate malocclusion with the contextual factors of quality of life and socioeconomic status.

Material and methods

This epidemiologic, observational, cross-sectional, and analytic study was conducted with 1256 children from 7 to 10 years of age, selected at 11 public schools in Piracicaba, São Paulo, Brazil, using the probabilistic sampling technique by conglomerates. The sample size was calculated based on previous studies of dental caries and occlusal problems, considering that 50% of the children between 7 and 10 years of age have malocclusion, admitting a sample error of 5%, confidence interval of 95%, sample loss of 20%, and design error equal to 2. In addition, a test power of 80% with a level of significance of 5% and minimum odds ratio of 1.5 was considered in the gross and adjusted analyses, thereby obtaining a minimum sample of 924 randomly selected subjects.

The children included in the sample were enrolled in public schools, in the age range from 7 to 10 years; those excluded had undergone or were undergoing orthodontic treatment, in addition to those with physical or psychological problems that could prevent the examinations from being performed.

Data were collected with structured questionnaires and clinical dental examinations. For determination of the socioeconomic status, data made available by the Research and Planning Institute of Piracicaba, São Paulo, Brazil, were used and dichotomized into high and low socioeconomic status.

The influence of malocclusion on quality of life was determined with the Child Perceptions Questionnaire (CPQ). The OHRQoL in children questionnaire was designed for the age range of 6 to 14 years, with the aim of incorporating the perceptions of both children and parents, since it is sensitive to cognitive and emotional development. Because of the great variability in children’s perceptions, according to their different ages, the impact of the OHRQoL was measured using the Brazilian version of the CPQ (CPQ 8-10). This instrument includes 25 items distributed among 4 subscales: oral symptoms (5 items), functional limitations (5 items), emotional well-being (5 items), and social well-being (10 items). The items address the frequency of events in the 4 previous weeks. A 5-point rating scale is used, with the following options: never, 0; once or twice, 1; sometimes, 2; often, 3; and every day or almost every day, 4. The CPQ 8-10 scores are calculated by adding up all the scores, with the total score ranging from 0 (no impact of oral conditions on OHRQoL) to 100 (maximum impact of oral conditions on OHRQoL).

In the clinical examination, anteroposterior relationship, overjet, overbite, crossbite, and crowding were evaluated using criteria recommended by Foster and Hamilton and Grabowski et al. The anteroposterior relationship was determined by the intercuspidation of the canines and classified as Class I (the maxillary deciduous canine was in the same plane as the distal surface of the mandibular canine), Class II (the maxillary deciduous canine was in a relationship anterior to the distal surface of the mandibular deciduous canine), and Class III (the maxillary deciduous canine was in a relationship posterior to the distal surface of the maxillary deciduous canine). The asymmetrical relationships between the deciduous canines were also evaluated. Normal overjet was defined as no distance between the maxillary and mandibular incisors (overjet, 0 mm). Increased overjet (>2 mm) and anterior crossbite (<0 mm) were measured. Anterior crossbite was recorded when the mandibular incisors were in front of the maxillary incisors. Anterior open bite was recorded in subjects with no contact between the anterior teeth when the posterior teeth were in occlusion. Normal overbite was designated when the maxillary incisors overlapped the mandibular incisors by no more than 2 mm. Overbite greater than 2 mm was designated as deepbite. Posterior crossbite was recorded when the maxillary deciduous molars were occluded in a lingual relationship with the mandibular deciduous molars in centric occlusion. The children were diagnosed with malocclusion when they had at least 1 of these conditions.

Statistical analysis

Initially, bivariate individual analyses were performed, and the gross odds ratios and respective confidence intervals were estimated. After this, starting with the variables showing P ≤0.20 in the bivariate analyses, multilevel multiple logistic regression models were estimated by means of the PROC GENMOD procedure in the statistical software program (version 9.3; SAS Institute, Cary, NC). At level 1, the variables relative to the subjects were considered; at level 2, the variables relative to context were considered. In this analysis of binomial distribution, the function of logistic connection and the criterion of permanence in the model at P ≤0.05 were considered. Adjustments of the models were evaluated by the criterion “quasi-likelihood under independence model criterion.” All analyses were performed with the SAS software program.


Table I presents the descriptive and bivariate analysis data. In total, 1256 children (47.21% boys, 52.79% girls) in the age range of 7 to 10 years were examined. The sample was dichotomized by age group into 7 to 8 years (51.5%) and 9 to 10 years (48.5%) and by socioeconomic status (high and low), with 45.06% having the lower status. Of all the children examined, 82.1% had some type of malocclusion. Considering the bivariate analysis according to the levels and with regard to the subjects, sex had no statistical significance associated with malocclusion; however, age showed a significant association ( P <0.05). In level 2, contextual, the independent variable socioeconomic status had statistical significance ( P <0.05).

Table I
Bivariate analysis of malocclusion and socioeconomic status of 1256 subjects
Variable Malocclusion present, n (%) Crude odds ratio (95% CI) P value
Individual level
Male 484 (81.6%) Reference 0.6861
Female 547 (82.5%) 1.06 (0.80, −1.42)
Age (y)
7-8 504 (78.0%) Reference <0.0001
9-10 527 (86.4%) 1.79 (1.72, −1.86)
Contextual level, socioeconomic status
High 543 (78.7%) Reference 0.0005
Low 488 (86.2%) 1.69 (1.25, −2.29)

1031 (82.1%) had malocclusion.

division by median.

The multilevel logistic regression analysis is presented in Table II . In model 1, the variable age was associated with malocclusion and was maintained in the model ( P <0.0001). In model 2, with the socioeconomic contextual variable included in the analysis, statistical significance was observed for the variables of age and socioeconomic status ( P ≤0.05), and reduction of the random effect (quasi-likelihood under independence model criterion) in comparison with the model with only age, indicating that although it appears to be an important factor in the development of malocclusion, the contextual variable, socioeconomic status, may also be an important explanatory factor in development. Thus, in the model, the increase in age associated with a lower socioeconomic status is the best explanatory model for the determination of a malocclusion.

Table II
Multilevel logistic regression analysis between occlusal problems and sociodemographic variables
Model 1 Model 2
Estimate (SE) Odds ratio adjusted (95% CI) P value Estimate (SE) Odds ratio adjusted (95% CI) P value
Intercept −0.37 (0.01) <0.0001 −0.28 (0.07) <0.0001
Individual level
Age (y)
7-8 Reference Reference <0.0001
9-10 0.23 (0.02) 1.26 (1.22, −1.31) <0.0001 0.20 (0.01) 1.22 (1.20, −1.25)
Contextual level, socioeconomic status
High Reference <0.0001
Low 0.40 (0.01) 1.49 (1.48, −1.51)
QIC 1168.29 1155.25
Division by median; quasi-likelihood criterion information.

Table III presents the association of the outcome variable OHRQoL, with variables associated with the individual level (sex, age, and type of malocclusion) and the contextual level (socioeconomic status). Individual analyses were performed, and the gross odds ratio was estimated ( P <0.05). In the individual analyses, the variables of sex, increased overjet, and socioeconomic status showed a statistically significant association ( P <0.05) with the OHRQoL. Although they did not attain the level of significance of 5%, the variables deepbite ( P <0.0845) and Class II malocclusion ( P <0.0769) showed important results in the association with OHRQoL and deserve to be considered.

Table III
Association between OHRQol and type of malocclusion
Variable (type of occlusal problem) OHRQol Crude odds ratio (95% CI) P value
611 (%)
645 (%)
Individual level
Male 257 (43.3%) 336 (56.7%) Reference
Female 354 (53.4%) 309 (46.6%) 1.50 (1.20-1.87) 0.0004
Age (y)
7-8 308 (47.7%) 338 (52.3%) Reference
9-10 303 (49.7%) 307 (50.3%) 1.08 (0.87-1.35) 0.4798
No 458 (46.1%) 535 (53.9%) Reference
Yes 153 (58.2%) 110 (41.8%) 1.62 (1.23-2.14) 0.0005
No 434 (50.3%) 429 (49.7%) Reference
Yes 177 (45.0%) 216 (55.0%) 0.81 (0.64-1.03) 0.0845
Anterior crowding
No 323 (48.6%) 341 (51.4%) Reference
Yes 288 (48.6%) 304 (51.4%) 1.00 (0.80-1.25) 0.9989
Anterior crossbite
No 605 (48.6%) 641 (51.4%) Reference
Yes 6 (60.0%) 4 (40.0%) 1.59 (0.45-5.66) 0.4746
Open bite
No 490 (47.7%) 537 (52.3%) Reference
Yes 121 (52.8%) 108 (47.2%) 1.23 (0.92-1.64) 0.1609
Posterior crossbite
No 544 (48.2%) 585 (51.8%) Reference
Yes 67 (52.8%) 60 (47.2%) 1.20 (0.83-1.73) 0.3289
Anteroposterior relationship
Class I 195 (45.8%) 231 (54.2%) Reference
Class II 127 (52.9%) 113 (47.1%) 1.33 (0.97-1.83) 0.0769
Class III 37 (53.6%) 32 (46.4%) 1.37 (0.82-2.28) 0.2267
Atypical 193 (48.5%) 205 (51.5%) 1.11 (0.85-1.47) 0.4348
Educational level, socioeconomic status
High 310 (44.9%) 380 (55.1%) Reference 0.0036
Low 301 (53.2%) 265 (46.8%) 1.39 (1.11-1.74)
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Apr 4, 2017 | Posted by in Orthodontics | Comments Off on Association between malocclusion and the contextual factors of quality of life and socioeconomic status
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