OUP user menu

Negative self-perception of smile associated with malocclusions among Brazilian adolescents

Cristiano Moura, Alessandro Leite Cavalcanti, Estela Santos Gusmão, Renata de Souza Coelho Soares, Fabiana Torres Cavalcante Moura, Patrícia Morgana Hordonho Santillo
DOI: http://dx.doi.org/10.1093/ejo/cjs022 483-490 First published online: 24 April 2012


This study estimated the prevalence of negative self-perception of smile because of occlusion abnormalities and investigated their association according to standard clinical criteria. The sample consisted of 1290 randomly selected Brazilian adolescent boys and girls aged 12–16 years. The outcome of interest was dissatisfaction with smile, and data were collected using a standardized questionnaire. Occlusion characteristics were assessed using the dental aesthetic index (DAI). The other study variables were gender, age, and use of dental services. A chi-square test and Poisson multiple regression were used for statistical analysis. Of the 1290 students interviewed and examined, 539 (41.8 per cent) were dissatisfied with their smile; of these, 373 (69.2 per cent) assigned their dissatisfaction to the presence of an occlusal abnormality, and 166 (30.8 per cent) reported reasons other than occlusal abnormalities for their negative self-perception of their smile. In multivariate analysis, the following variables were associated with the outcome of interest: maxillary anterior irregularity [prevalence ratio (PR) = 1.40; 95 per cent confidence interval (CI) = 1.29–1.80], incisal spacing (PR = 1.37; 95 per cent CI = 1.19–1.57), vertical open bite (PR = 1.34; 95 per cent CI = 1.15–1.55), mandibular anterior irregularity (PR = 1.29; 95 per cent CI = 1.14–1.46), permanent anterior teeth missing (PR = 1.21; 95 per cent CI = 1.05–1.39), and incisal diastema (PR = 1.14; 95 per cent CI = 1.01–1.31). The negative self-perception of smile was statistically associated with severity of occlusal disorders according to the DAI scores, which suggests that self-perception should be used together with standard clinical criteria when decisions about orthodontic treatments are made in public health care systems.


Malocclusions, classified as problems of maxillary and mandibular growth and development during childhood and adolescence, may result in functional (Suliano et al., 2007; Magalhães et al., 2010), aesthetic (Josefsson et al., 2005; Hamamci et al., 2009; Josefsson et al., 2009; Jung, 2010; Nagarajan and Pushpanjali, 2010; Verdecchia et al., 2011), and psychosocial (Onyeaso and Sanu, 2005; Baker et al., 2010) disorders that may have a negative impact on quality of life (Liu et al., 2011) because of their association with low self-esteem, stigmatization, employment difficulties, embarrassment, and shyness (Klages et al., 2005).

In this sense, the negative self-perception of smile may be understood as the result of feelings raised by dissatisfaction and associated with social, cultural, psychological, and environmental factors (Shaw, 1981; Gosney, 1986; Espeland et al., 1992). The severity of malocclusion may have an important impact on the self-perception of adolescents (Shaw, 1981; Tedesco et al., 1983) and a negative effect on their quality of life (O’Brien and Benson, 2007).

For patients, determining orthodontic treatment needs is affected by several factors: dissatisfaction with dentofacial appearance, functional, financial, and social issues, and the assessment of a dental professional, usually an orthodontist (Shaw, 1981; Gosney, 1986; Birkeland et al., 1999; Phillips and Beal, 2009).

Most of the indices used for the diagnosis and classification of malocclusion are essentially based on clinical and epidemiological criteria (Borges et al., 2010). However, the instruments based on normative criteria only do not take into consideration the opinion of individuals about their own health or aesthetics or their perception of which occlusal disorders are a problem for them (Marques et al., 2005, 2006, 2009). The possible inclusion of subjective evaluations about the impact of malocclusion on the life of individuals in epidemiological surveys may provide information for the allocation of public resources and the definition of priority groups for orthodontic treatment in the health care system (Locker et al., 2007).

International studies (Shaw et al., 1975; Hancock and Blinkhorn, 1996; Mandall et al., 2000) have demonstrated that clinical and epidemiological criteria for the diagnosis of malocclusion overestimate problems when compared with the perception of individuals.

The need for orthodontic treatment is difficult to define and, in most cases, based on a professional viewpoint (Marques et al., 2006). In contrast, the demand for orthodontic treatment among adolescents is primarily motivated by personal concerns about appearance and other psychosocial factors (Bernabé and Flores-Mir, 2006; Hamdam et al., 2007).

This study investigated the association of dissatisfaction with smile and occlusal characteristics with occlusal abnormalities found in students aged 12–16 years to test the hypothesis that this subjective parameter is associated with severity of malocclusion.

Subjects and methods

This cross-sectional study was registered in the Brazilian System for Information on Ethics in Research with Human Beings (Sisnep; CAAE 0098.0.133.000-05) and approved by the Ethics in Research Committee of the Universidade Estadual da Paraíba (CEP-UEPB). It included adolescent boys and girls regularly attending school in any of 41 of the 90 municipal urban schools in Campina Grande, a city in the state of Paraíba, Brazil, in 2006 and 2007. Participants’ age ranged from 12 to 16 years. Random sampling was used, and cluster sampling was divided into two stages: selecting schools and selecting students. Sample size was calculated at 750 students considering an estimated 50 per cent prevalence for the outcome of interests at a 95 per cent confidence interval (CI) and a 5 per cent error margin. An extra 20 per cent was added because of possible losses and refusals to participate and a sample design effect of 1.5. According to calculations, sample size should be 1350 students, distributed proportionally in the six health care districts of the urban area of the city of Campina Grande.

The municipal public schools selected for this study were located in the six health districts that correspond to the whole urban area of the city of Campina Grande. Therefore, the draft to select schools reflected the proportional distribution of the population in these health districts so that all the socio-economic groups in the city were represented.

Inclusion criteria were age 12–16 years, presence in school at the time of physical examination (examination of the oral cavity), not having received any orthodontic treatment, and having an informed consent term signed by a parent or guardian.

The final study sample comprised 1290 adolescents. Loss was 4.5 per cent (n = 58), which is within the margin expected for this stage of sample size calculation. These losses were 12 adolescents absent on the days of the interviews and examinations, 32 adolescents undergoing endodontic treatment at the time, and 14 adolescents that did not submit the informed consent term signed by their parents or guardians at the time of the interviews and examinations.

Before data collection, a pilot study was conducted with 55 students randomly selected. This study tested the standardized questionnaire and the clinical form that was later used for data collection. The students were examined and then re-examined 7 days later by the same observer, and the Pearson correlation coefficient (r) was 0.952. Inter-examiner agreement for each type of malocclusion was good to excellent (maximal and minimal kappa values were 1.00 and 0.79). The two dentists with the highest agreement with one of the authors (the criterion standard was the evaluation by CM, a specialist in orthodontics with expertise in the field) were appointed as examiners. During data collection, 65 adolescents were re-examined, and intra- and inter-examiner agreement was calculated using kappa, with results ranging from 0.88 to 0.91.

Interviews and physical exams were conducted in free areas of the school under natural light using visual and tactile inspection, dental mirrors, and the WHO-621 Trinity (São Paulo, SP, Brazil) probe or Community Periodontal Index probe, recommended by the World Health Organization (WHO) guidelines (WHO, 1997) for epidemiological surveys, which had a 0.5 mm diameter sphere at the working tip and a black band at 3.5 and 5.5 mm from the end of the probe. The measurements made using this probe, however, are approximate and not exact. Examiners were adequately dressed according to infection control norms (use of disposable caps, gloves, and mask).

The dependent study variable was dissatisfaction when smiling due to occlusal problems, assessed using the following question: are you satisfied with your appearance when you smile? (yes/no). Those adolescents that were dissatisfied with their smiles were asked why, and based on their answers, the outcome variable was defined: dissatisfaction with smile due to occlusal problems (yes/no).

The main exposure under study was the presence of occlusal abnormalities according to the dental aesthetic index (DAI; Cons et al., 1986), which assesses dental and facial abnormalities based on three groups: dentition, expressed as number of maxillary and mandibular missing permanent incisors, canines, and premolars that result in aesthetic problems; spacing, assessed according to incisal crowding, incisal spacing, incisal diastema (in mm), and maxillary and mandibular anterior irregularities (in mm); and occlusion, assessed according to maxillary and mandibular anterior overjet (in mm), vertical open bite (in mm), and the antero-posterior molar relationship. The DAI provides a classification based on scores according to the following outcomes: no or minor occlusal abnormalities that do not require orthodontic treatment (DAI ≤ 25); malocclusion, whose treatment is elective (DAI = 26–30); severe malocclusion, whose treatment is highly recommended (DAI = 31–35); and severe or incapacitating malocclusion whose treatment is essential (DAI ≥ 36; Table 1).

View this table:
Table 1

Standard dental aesthetic index (DAI) scoring table.

Another transverse occlusal abnormality, although not part of the index described above, was investigated: crossbite (yes/no) and its classification: anterior, unilateral posterior, bilateral posterior, and combined (anterior + unilateral posterior and anterior + bilateral posterior).

The other independent variables (potential confounding and mediating factors) were gender, age, visits to dentist (yes/no), time from last dental visit (never visited the dentist, less than 1 year, 1–2 years, and 3 years or more), and the type of dental service provider (never visited the dentist and public or private health care service).

The SPSS 18.0 and Stata 9.0 were used for descriptive and inferential data analysis. A chi-square test for heterogeneity and linear tendency was used in bivariate analysis including the outcome of interest and the independent variables. Poisson regression was used for crude and adjusted analyses, and robust variance was calculated to determine prevalence ratios (PRs) and 95 per cent CI. The level of significance for all analyses was set at P < 0.05. The variables with P < 0.02 in the chi-square test, which were clearly significant in bivariate analysis, were included in multivariate analysis. The final model retained only the variables that had P < 0.05 in multivariate analysis, adjusted for confounding and mediating factors in the comparison between each other.


Of the 1290 students interviewed and examined, 539 (41.8 per cent) were dissatisfied with their smile; of these, 373 (69.2 per cent) assigned their dissatisfaction to the presence of an occlusal abnormality, and 166 (30.8 per cent) reported reasons other than occlusal abnormalities for their negative self-perception of their smile.

Most students dissatisfied with their smile were girls (55.4 per cent) aged 12 years (45.6 per cent). Crude analysis revealed statistically significant differences in dissatisfaction with smile reported as owing to occlusal abnormalities for ages 13 and 14 years but not for gender (Table 2).

View this table:
Table 2

Crude analysis of sample distribution, prevalence of dissatisfaction with smile due to occlusal reasons, prevalence ratio (PR), and 95% confidence interval (CI) according to demographic variables and the use of dental services.

Of the students dissatisfied with their smile, most (80.7 per cent) had already been to the dentist at least once in their lives, and the time interval from their last dental visit was less than a year for most (52.0 per cent), and most used the public health care system (64.1 per cent). The independent variables visit to dentist and type of service used had statistically significant differences (Table 2).

The analysis of occlusal problems reported by adolescents revealed that the reason for dissatisfaction with their smile in most cases (63.0 per cent, 235 students) was incisal crowding. The other frequently reported reasons were incisal diastema (11.0 per cent), incisal spacing (9.0 per cent), and missing anterior teeth (3.0 per cent). Only eight (2.0 per cent) adolescents reported anterior mandibular overjet as a reason for dissatisfaction with their smile.

Negative self-perception because of occlusal abnormalities was associated with the following anomalies in crude analysis, in order of descending strength of association: maxillary and mandibular anterior irregularity more than or equal to 2 mm, incisal diastema more than or equal to 2 mm, incisal spacing, incisal crowding and missing incisors, and canines or premolars (Table 3).

View this table:
Table 3

Crude analysis of sample distribution, prevalence of dissatisfaction with smile due to occlusal reasons, prevalence ratio (PR), and 95% confidence intervals (CIs) according to occlusal abnormalities. DAI, dental aesthetic index.

According to the study criteria, students with DAI scores more than or equal to 36 had greater PRs for dissatisfaction with smile (27.1 per cent), and this association was stronger (PR = 1.52; 95 per cent CI = 1.29–1.80; P < 0.001; Table 3).

Crossbite was found in 113 (33 per cent) of those who were dissatisfied with their smile. The analysis of crossbite according to its different types revealed that a greater percentage of children with unilateral posterior crossbite (11.6 per cent) corresponded to a greater prevalence of dissatisfaction with smile because of occlusal abnormalities (14.0 per cent). No statistically significant difference was found between presence of crossbite and its different types and the outcome of interest (Table 3).

Permanent anterior teeth (incisors, canines, and premolars) were missing in only 44 (11.8 per cent) of the 373 students dissatisfied with their smile (Table 3).

Adjusted analysis revealed that missing anterior teeth, greater incisal spacing, incisal diastema, maxillary anterior irregularity, mandibular anterior irregularity, and vertical open bite more than or equal to 2 mm were directly associated with reported dissatisfaction with smile (Table 4).

View this table:
Table 4

Crude and adjusted prevalence ratios (PRs) of dissatisfaction with smile due to occlusal reasons and 95% confidence interval (CI) according to occlusal abnormalities.


The high response rate (95.5 per cent) of the total sample, the good intra- and inter-examiner agreement for the occlusal abnormalities under study, and the representativeness of the sample for the target population ensured the consistency and reliability of this study results.

The perception and awareness developed by adolescents to identify oral problems have been demonstrated in several studies (Moura and Cavalcanti, 2008; Marques et al., 2009; Borges et al., 2010; Nagarajan and Pushpanjali, 2010). However, the perception that adolescents have of occlusal abnormalities do not often agree with standard clinical findings (Mandall et al., 2000; Peres et al., 2002).

In this study, the outcome was negative self-perception of smile because of occlusal abnormalities as reported by the adolescents. This subjective measure was more accurate because our comparison group consisted of adolescents who were dissatisfied with their smile but did not report occlusal abnormalities as the reason for their dissatisfaction, which was assigned to other reasons, such as clinical signs of caries in anterior teeth, yellow teeth, and swollen gingiva. Therefore, this study sought to bring proximity between the subjective measure under analysis and the standard clinical criteria used to define malocclusion.

The prevalence of dissatisfaction with smile among the adolescents interviewed was 41.8 per cent, which confirms findings of studies conducted in Turkey (42.7 per cent; Akarslan et al., 2009) and Nigeria (57.4 per cent; Onyeaso and Sanu, 2005) but differs from those found in Tanzania (23.3 per cent; Mtaya et al., 2008). Therefore, the self-perception of smile should be analysed using a multidimensional approach that takes into consideration the different individual understandings about health in face of the existing cultural and psychosocial contexts. However, of those adolescents who were unhappy with their smile, the main reason for dissatisfaction for 69.2 per cent was occlusal abnormalities. These comparisons should be made carefully because of the differences in methods, such as the different age groups, the types of indices, and the methods classifying variables (Zhang et al., 2009).

Our results confirm the view that adolescents assign great importance to dental appearance (Klages et al., 2005; Bernabé and Flores-Mir, 2006). Most adolescents (77.0 per cent) reported that incisal crowding was the main reason of dissatisfaction with their smile. The other frequently reported occlusal problems were incisal diastema, incisal spacing, and missing permanent anterior teeth, changes that have a direct impact on dentofacial aesthetics.

Of the adolescents that were dissatisfied with their smile due to occlusal problems, 170 (45.6 per cent) were 12 years old. Two aspects should be analysed in the attempt to explain this finding: the proportional nature of the sample because there were more students in this age group registered in the school and the fact that, at this age, not all teeth have erupted fully. This study also revealed differences, although minor, in negative self-perception of smile between adolescents 13 and 14 years when compared with those that were 12 years old. However, adolescence is a period of transition from childhood to adulthood and is often associated with increased self-consciousness, confusion about identity and acceptance by others, and concerns about recognition from adults and peers (Nagarajan and Pushpanjali, 2010). During adolescence, a person is very sensitive to the responses of significant others, especially concerning appearance (Josefsson et al., 2010). A study (Brown and Moerenhout, 1991) disclosed that, compared to adults (more than or equal to 18 years), adolescents (14–17 years) are more vulnerable to undesirable psychological effects of orthodontic treatment.

In this sense, occlusal changes that involve aesthetic compromise, such as missing incisors, canines and premolars, incisal crowding and spacing, incisal diastema, maxillary and mandibular irregularity, and vertical open bite, were classified as risk factors for reported dissatisfaction with smile in this study based on crude analysis. These findings are different from those reported in a cross-sectional study with 315 students aged 14–18 years in Florianópolis, Brazil, which evaluated the impact of technically defined orthodontic needs on the satisfaction with appearance and mastication and did not find any effect of the occlusal abnormalities described earlier on self-perception of appearance (Peres et al., 2002). However, other studies (Espeland et al., 1992; Marques et al., 2009; Borges et al., 2010; Paula et al., 2011) point to the association found in our study.

One of the principal findings of our study was the increase of dissatisfaction with smile concurrent with an increase in malocclusion severity, which confirmed the initial hypothesis of this study. This finding confirms the evidence found in another study (Borges et al., 2010) conducted in Brazil, whose objective was to investigate the association between occlusal abnormalities and self-assessment of dental and gingival appearance among Brazilian adolescents. That study found associations between all types of occlusal abnormalities and dissatisfaction with the appearance of teeth and gingiva. In another study (Nagarajan and Pushpanjali, 2010) conducted in Bangalore, India, negative self-perception of dental appearance in adolescent students aged 14 and 15 years increased considerably with the severity of occlusal abnormalities and are in agreement with the results described. Their findings reinforced the importance of taking into consideration subjective measures when the purpose is to identify occlusal problems that negatively affect the life of adolescents.

Another relevant finding of this study was the prevalence of crossbite in the group of students with a negative self-perception of their smile (30.3 per cent), although no significant differences were found when compared with the outcome of interest. In fact, such transverse occlusal abnormality is not on the list of dentofacial anomalies assessed using the DAI, which may be a flaw of this index as it may underestimate scores because of the exclusion of this abnormality. Therefore, other studies should be conducted to elucidate the effect of crossbite in the DAI.

The analysis of demographic data and use of dental services revealed that a greater percentage of female adolescents were dissatisfied with their smiles and considered abnormal occlusion to be the reason of their dissatisfaction, although, in general, only the negative self-perception of smile was considered, regardless of the justification presented. Female adolescents had the greatest dissatisfaction, which confirmed findings reported in other studies (Hamamci et al., 2009; Jung, 2010). However, no statistically significant differences were found between gender and outcome in the present study.

Therefore, standard criteria should be used in conjunction with either DAI or other indices that better express orthodontic treatment needs. Subjective self-perception criteria are an epidemiological tool for oral health to be applied in population surveys and, above all, to contribute to the allocation of resources and definition of criteria in the orthodontic services offered by public health care systems.


This study found that maxillary anterior irregularity more than or equal to 2 mm, incisal spacing, vertical open bite more than or equal to 2 mm, mandibular anterior irregularity more than or equal to 2 mm, missing maxillary teeth, and incisal diastema were directly associated in descending order of strength of association, with the reported dissatisfaction with smile. The hypothesis raised for this study, that is, that dissatisfaction with smile was associated with severity of occlusal abnormalities, was confirmed based on the statistically significant association between the subjective parameter and the DAI scores.


The study was self-funded by the authors and their institutions.


View Abstract