Abstract

INTRODUCTION

The epidemiological profile of oral health problems has changed, especially in children aged 12. In Brazil, tooth decay has shown a decrease in the DMFT index (decayed, missing and filled teeth) from 6.7 in 1986 to 2.07 in 2010 and, currently, a significant number of those children are free of caries (43.5%). ^aaMinistério da Saúde (BR). Secretaria de Vigilância em Saúde. Secretaria de Atenção à Saúde. Coordenação Nacional de Saúde Bucal. SB2010: Pesquisa Nacional de Saúde Bucal. Resultados principais. Brasília (DF); 2011[cited 2012 Feb 08]. Available from: http://dab.saude.gov.br/cnsb/sbbrasil/download.htm Therefore, other problems related to the oral cavity have begun to receive attention, among them, occlusal changes stand out. ¹⁴14 . Roncalli AG, Unfer B, Costa ICC, Arcieri RM, Guimarães LOC, Saliba NA. Levantamentos epidemiológicos em saúde bucal: análise da metodologia proposta pela Organização Mundial da Saúde. Rev Bras Epidemiol . 1998;1(2):177-89. DOI: 10.1590/S1415-790X1998000200008
https://doi.org/10.1590/S1415-790X199800... Due to its high prevalence, the World Health Organization (WHO) now considers malocclusion to be the third largest public health problem in dentistry. ⁹9 . World Health Organization. Health through oral health: guidelines for planning and monitoring for oral health care. London; 1989. ^{, 10}10 . Organização Mundial da Saúde. Levantamento epidemiológico básico de saúde bucal. 3. ed. São Paulo; 1991.

National data relating to malocclusion indicate a prevalence of 40.0% for the index age of 12 years. For severe, and very severe malocclusion, the prevalence is 10.4% and 7.1% respectively. ^aaMinistério da Saúde (BR). Secretaria de Vigilância em Saúde. Secretaria de Atenção à Saúde. Coordenação Nacional de Saúde Bucal. SB2010: Pesquisa Nacional de Saúde Bucal. Resultados principais. Brasília (DF); 2011[cited 2012 Feb 08]. Available from: http://dab.saude.gov.br/cnsb/sbbrasil/download.htm In many cases, malocclusion can impact on the quality of life of this part of the population. It can produce aesthetic deviations in the teeth and/or face and functional disturbances of occlusion, chewing, swallowing, pronunciation and breathing. It can also cause psychosocial disorders with potential repercussions on the self-esteem and interpersonal relationships of severely affected individuals. ⁵5 . Danaei SM, Salehi P. Association between normative and self-perceived orthodontic treatment need among 12- to 15-year-old students in Shiraz, Iran. Eur J Orthod . 2010;32(5):530-4. DOI: 10.1093/ejo/cjp139
https://doi.org/10.1093/ejo/cjp139...

In the face of this reality, there is a need for a clearer picture in order to understand the disease process in relation to malocclusion. Thus, in addition to individual factors, other factors, called modifiers or modulators (social, economic, cultural, ethnic/racial, psychological and behavioral factors), are related to the health of the population. Currently, these factors are known as social determinants of health. ¹²12 . Peres KG, Peres MA, Boing AF, Bertoldi AD, Bastos JL, Barros AJD. Redução das desigualdades na utilização de serviços odontológicos no Brasil entre 1998 e 2008. Rev Saude Publica . 2012;46(2):250-9. DOI: 10.1590/S0034-89102012000200007
https://doi.org/10.1590/S0034-8910201200...

In contextual terms, some health indicators and social factors may contribute to better identifying groups or individuals vulnerable to diseases. Among these indicators, the Human Development Index (HDI) is a comparative measure used to rank countries by their level of “human development”. ^bbPrograma das Nações Unidas para o Desenvolvimento. Desenvolvimento Humano e IDH. Brasília (DF); 2012[cited 2012 Mar 10]. Available from: http://www.pnud.org.br/idh/

Another indicator would be the “ Bolsa Família ” (BF, Family Allowance), a program of direct income transfer that benefits families (about 16 million Brazilians – 8.5% of the general population) with per capita income below 70 reais per month, based on the guaranteed income, productive inclusion and access to public services, ^ccMinistério do Desenvolvimento Social e Combate à Fome (BR). Programa Bolsa Família. Brasília (DF); 2012 [cited 2012 Mar 15]. Available from: http://www.mds.gov.br/bolsafamilia which represents the state of vulnerability directly linked to economic development. The Performance Index of the Brazilian public health system (IDSUS, Índice de Desempenho do Sistema Único de Saúde ), ^ddMinistério da Saúde (BR). IDSUS - Índice de Desempenho do Sistema Único de Saúde. Brasília (DF); 2011 [cited 2012 Mar 08]. Available from: http://portal.saude.gov.br/portal/saude/area.cfm?id_area=1080 the score of which varies between zero to ten, evaluates the access and quality of health services. The lowest scores represent the worst performances of SUS for Brazil and for each county and state. ¹1 . Ben-Shlomo Y, Kuh D. A life course approach to chronic disease epidemiology conceptual models, empirical challenges and interdisciplinary perspectives. Int J Epidemiol . 2002;3(2):285-93. DOI: 10.1093/ije/31.2.285
https://doi.org/10.1093/ije/31.2.285...

In order to better understand the factors closely related to the problem, the aim of this study was to evaluate the association between the prevalence of malocclusion in Brazilian 12-year-olds with individual and contextual variables.

METHODS

This was a cross-sectional analytical study. Data from the national epidemiological survey of oral health (SBBrasil 2010) were used. ^aaMinistério da Saúde (BR). Secretaria de Vigilância em Saúde. Secretaria de Atenção à Saúde. Coordenação Nacional de Saúde Bucal. SB2010: Pesquisa Nacional de Saúde Bucal. Resultados principais. Brasília (DF); 2011[cited 2012 Feb 08]. Available from: http://dab.saude.gov.br/cnsb/sbbrasil/download.htm This epidemiological survey examined the oral health status of the population in different age groups in urban and rural areas. Brazil has a total of 190,755,799 individuals, 3,402,242 of those are children aged 12. ^eeInstituto Brasileiro de Geografia e Estatística (BR). Pesquisa nacional por amostra de domicílios: acesso e utilização de serviços de saúde. Rio de Janeiro; 2010 [cited 2012 Feb 15]. Available from: http://censo2010.ibge.gov.br/home/estatistica/pesquisas/pesquisa_resultados.php?id_pesquisa=40 There were 37,519 individuals examined in the 26 state capitals, the Federal District and 150 municipalities with different population sizes.

The database generated in this research is in the public domain and is freely accessible on the Ministério da Saúde webpage. ^eeInstituto Brasileiro de Geografia e Estatística (BR). Pesquisa nacional por amostra de domicílios: acesso e utilização de serviços de saúde. Rio de Janeiro; 2010 [cited 2012 Feb 15]. Available from: http://censo2010.ibge.gov.br/home/estatistica/pesquisas/pesquisa_resultados.php?id_pesquisa=40

Data collection was performed in the home, including oral examinations and interviews using a structured questionnaire. The oral health teams were composed of an examiner – a dental surgeon, and an auxiliary note taker. For the clinical examination, instruments recommended by the WHO were used (mouth mirror and Community Periodontal Index CPI dental probe). ⁹9 . World Health Organization. Health through oral health: guidelines for planning and monitoring for oral health care. London; 1989.

The presence of malocclusion was recorded using the Dental Aesthetic Index (DAI), categorized as: normal, set, severe and very severe. ⁴4 . Cons NC, Jenny J, Kohout FJ. DAI: the dental aesthetic index. Iowa City: College of Dentistry, University of Iowa; 1986. The basic principle of the DAI is a combination of measures that together express the occlusal state of the individual and the associated need for orthodontic treatment, which considers aesthetic commitment, beyond occlusion. Altogether, there are 11 steps, considering three major dimensions to be assessed: dentition, space and occlusion itself.

The sampling technique used by SBBrasil 2010 was probabilistic cluster sampling. For 12-year-olds, three strata were used: the first used domains and the primary sampling units: capital and interior municipalities according to macro region. The second consisted of the subdivision of the participating municipalities: 27 capitals plus 30 municipalities in each macro region. And the third was done by random selection to ensure the representativeness of the municipalities, census tracts and households.

Between 1 and 250 participants were evaluated per city in 172 cities around Brazil, totaling 7,328 children aged 12, with a sample loss of 8.4 %. To calculate the sample size, the parameters used (z value, variance, mean of the DMFT, acceptable margin of error, design effect and non-response rate) were those from the SBBrasil 2003. ^ffMinistério da Saúde (BR). Secretaria de Atenção à Saúde. Projeto SB Brasil 2003: condições de saúde bucal da população brasileira 2002-2003. Resultados principais. Brasília (DF); 2004[cited 2012 Feb 08]. Available from: http://dtr2001.saude.gov.br/editora/produtos/livros/pdf/05_0053_M.pdf

The field teams were properly trained in workshops. The calibration technique adopted was consensus, calculating the correlation between each examiner and the results obtained by team consensus. The model proposed by the WHO was taken as a reference. The weighted kappa coefficient was calculated for each examiner, age group and health problem studied, with the minimum acceptable value of 0.65. For DAI, the WHO recommends the minimum value of 0.85 for inter-examiner and 0.95 to intra-examiner for the evaluation. ^aaMinistério da Saúde (BR). Secretaria de Vigilância em Saúde. Secretaria de Atenção à Saúde. Coordenação Nacional de Saúde Bucal. SB2010: Pesquisa Nacional de Saúde Bucal. Resultados principais. Brasília (DF); 2011[cited 2012 Feb 08]. Available from: http://dab.saude.gov.br/cnsb/sbbrasil/download.htm

The outcome studied was malocclusion, measured by DAI, calculated as follows:

DAI = (missing teeth x 6) + (API) + (ESP) + (DI x 3) + (DMXA) + (DMDA) + (OMXA x 3) + (OMDA x 4) + (MAA x 4) + (RMAP x 3) + 13

Codes and weights were defined as follows:

API: crowding in the incisal segment weight 1; ESP: incisal segment spacing Weight 1; DI: incisal diastema weight 3, DMXA: anterior maxillar misalignment weight 1, DMDA: anterior mandibular misalignment weight 1, OMXA: anterior maxillar overjet Weight 3, OMDA: anterior mandibular overjet weight 4, MAA: vertical anterior open bite weight 4 and RMAP: anteroposterior molar relation weight 3.

Thus, the scores are calculated and distributed according to the severity of the malocclusion and the need for orthodontic treatment as follows: absent (DAI < 25), set (DAI 26-30), severe (31-35 DAI) and very severe (DAI ≥ 36). ⁴4 . Cons NC, Jenny J, Kohout FJ. DAI: the dental aesthetic index. Iowa City: College of Dentistry, University of Iowa; 1986.

The HDI, a measure that gathers information on longevity, income and schooling, was used for contextual characterization. ^bbPrograma das Nações Unidas para o Desenvolvimento. Desenvolvimento Humano e IDH. Brasília (DF); 2012[cited 2012 Mar 10]. Available from: http://www.pnud.org.br/idh/

BF was obtained by the number of families receiving it for every 1,000 inhabitants in the municipality, aiming to standardize and facilitate comparison with other municipalities. ^ccMinistério do Desenvolvimento Social e Combate à Fome (BR). Programa Bolsa Família. Brasília (DF); 2012 [cited 2012 Mar 15]. Available from: http://www.mds.gov.br/bolsafamilia

The IDSUS register was achieved using the score that the municipality received from the evaluation and the number of homogeneous group into which the municipality was grouped. ^ddMinistério da Saúde (BR). IDSUS - Índice de Desempenho do Sistema Único de Saúde. Brasília (DF); 2011 [cited 2012 Mar 08]. Available from: http://portal.saude.gov.br/portal/saude/area.cfm?id_area=1080

The gross domestic product (GDP) per capita is the sum of the salaries of the entire population of the municipality divided by the number of inhabitants. ^eeInstituto Brasileiro de Geografia e Estatística (BR). Pesquisa nacional por amostra de domicílios: acesso e utilização de serviços de saúde. Rio de Janeiro; 2010 [cited 2012 Feb 15]. Available from: http://censo2010.ibge.gov.br/home/estatistica/pesquisas/pesquisa_resultados.php?id_pesquisa=40 Data were dichotomized into municipalities with and without fluoride in tap water. ^eeInstituto Brasileiro de Geografia e Estatística (BR). Pesquisa nacional por amostra de domicílios: acesso e utilização de serviços de saúde. Rio de Janeiro; 2010 [cited 2012 Feb 15]. Available from: http://censo2010.ibge.gov.br/home/estatistica/pesquisas/pesquisa_resultados.php?id_pesquisa=40

In the descriptive analysis, the data were evaluated by the chi-squared test. The multilevel model was made up of fixed components (known variables) and random components (cities and variances at different levels). ²¹21 . Zanini RR, Moraes AB, Giugliani ERJ, Riboldi J. Determinantes contextuais da mortalidade neonatal no Rio Grande do Sul por dois modelos de análise. Rev Saude Publica . 2011;45(1):79-89. DOI: 10.1590/S0034-89102011000100009
https://doi.org/10.1590/S0034-8910201100...

Adjustments to the multilevel model were performed using the PROC MIXED procedure from the SAS statistic program (SAS Institute Inc. 9.2, 2008) according to the methodology described in Singer ¹⁵15 . Singer JD. Using SAS proc mixed to fit multilevel models, hierarchical models, and individual growth models. J Educ Behav Stat . 1998;24(4):323-55. (1998) and Tellez et al ¹⁶16 . Tellez M, Sohn W, Burt BA, Ismail AI. Assessment of the relationship between neighborhood characteristics and dental caries severity among low-income African-Americans: a multilevel approach. J Public Health Dent . 2006;66(1). DOI: 10.1111/j.1752-7325.2006.tb02548.x
https://doi.org/10.1111/j.1752-7325.2006... (2006).

At level 1, the variables related to individuals were considered. At level 2 the variables were those related to cities, evaluating the behavior of the variable malocclusion (level 1) as a function of the predictor variables for levels 1 and 2.

Initially, one model was adjusted only with the intercept (model 1). Then the effects of individual-level predictors (level 1) – Model 2 – and cities (level 2) – Model 3 were included. In the selection of contextual variables indicators related to access to and quality of health services (IDSUS), socioeconomic conditions (HDI and GDP per capita ) and social vulnerability (BF) were taken into consideration.

The quality of the adjustments was evaluated using the convergence model, criteria from Akaike information criterion and Akaike information criterion corrected, and statistics – twice times the logarithm of the likelihood function. All analyses used a 5% level of significance.

The Project SBBrasil 2010 followed the standards set by the Declaration of Helsinki and was approved by the Conselho Nacional de Ética em Pesquisa , record no. 15,498, January 7 ^th , 2010.

RESULTS

The prevalence of children aged 12 with malocclusion classified as “severe” and “very severe” did not show statistical differences between regions, ranging from 17.8% in the North to 22.0% in the South, with a national mean of 19.8%. However, there was no statistically significant difference in the distribution of percentages of categories between different macro regions of the country (p < 0.0176) ( Table 1 ). Very severe malocclusion was identified in 9.4 % of the children examined.

The descriptive analysis of the independent variables (frequency and percentage) can be seen in Table 2 . Most of those examined (76.1%) lived in the capitals, while there was a balance between the different genres examined, basically half (51.3%) needed some kind of treatment, 75 % came from families with incomes below R$1,500, less than 5% came from families where the head of the household was attending a university course or had a university degree. As regards health variables, 23.7% reported having had toothache in the last six months, 81.6% had access to a dentist, the majority (60.1%) were satisfied with their teeth, while problems related to difficulty, discomfort or embarrassment related to the teeth and oral environment had little prevalence. Regarding contextual variables, the majority of participants (62.5%) lived in cities with high levels of socioeconomic development and 79.3% lived in cities with fluoridated tap water.

The cities of the participants had, on average, 54.56 families receiving benefits per 1,000 households. While the mean IDSUS was 5.68 (as a reference, 7 would be the limit for adequate performance according to the SUS), the mean per capita GDP was R$17,517 and mean HDI was 0.79, which is considered good ( Table 3 ).

As for the multilevel analysis, Model 1 shows that the average index score for malocclusion in cities was 1.68 with a standard error of 0.03 ( Table 4 ). The malocclusion variation between cities was significant (p < 0.001), but the variation between participants within cities was about 15 times larger than the variation between cities. According to the intra-class correlation coefficient, it can be affirmed that the variation between cities represented approximately 6.0% of the total variation.

When the individual level variables (model 2) were included, it was observed that male children (p = 0.03), with lower income (p = 0.05), who visited the dentist (p = 0.01), showing less satisfaction with mouth and teeth (p < 0.001) and feeling embarrassed to smile (p < 0.001) had the highest average index score for malocclusion. All these significances were controlled by the other predictors in the model.

In model 3 the variables of the second level (cities) were included in order to evaluate their influence in explaining the variability of malocclusion. It was found that the characteristics of the cities with the highest number of families receiving BF per 1,000 inhabitants, the worst scoring IDSUS and those with lower GDP per capita were associated with severity of malocclusion. All these significances were controlled by the significant predictor variables of the individual and cities.

DISCUSSION

Knowing the oral health status of population groups through epidemiological surveys is critical to the development of proposed actions appropriate to their needs and risks, as well as the possibility of comparisons that, retrospectively, allow the impact of these actions to be assessed, to plan and run services with equity.

The decline in dental caries, still the most prevalent oral health problem, allowed a new planning for oral health by health managers, bringing a new look at other problems, mainly due to increased awareness and expectations regarding oral health or increased availability of dental treatment. ²2 . Carvalho DM, Alves JB, Alves MH. Prevalence of malocclusion in schoolchildren with low socioeconomic status. Rev Gaucha Odontol . 2011;59(1):71-7. In this context, orthodontics was deemed eligible to access both the private and the public sector, due to its high prevalence, impact on aesthetics and influence on some respiratory problems, for example.

In Brazil, the most recent epidemiological studies concerning the population’s oral health, which took place in 2003 and 2010, showed a 19.3% reduction in the frequency of malocclusion, ranging from 58.1% to 38.8% at 12 years of age. In relation to severity, in 2003 the prevalence of the severe condition was 15.7% and very severe 20.7%. In 2010, for the same conditions, there was a reduction of 5.3% and 13.6%, respectively. ^aaMinistério da Saúde (BR). Secretaria de Vigilância em Saúde. Secretaria de Atenção à Saúde. Coordenação Nacional de Saúde Bucal. SB2010: Pesquisa Nacional de Saúde Bucal. Resultados principais. Brasília (DF); 2011[cited 2012 Feb 08]. Available from: http://dab.saude.gov.br/cnsb/sbbrasil/download.htm ^{, f}fMinistério da Saúde (BR). Secretaria de Atenção à Saúde. Projeto SB Brasil 2003: condições de saúde bucal da população brasileira 2002-2003. Resultados principais. Brasília (DF); 2004[cited 2012 Feb 08]. Available from: http://dtr2001.saude.gov.br/editora/produtos/livros/pdf/05_0053_M.pdf Even with a decline in the prevalence of malocclusion in children aged 12, this involvement can still be considered a public health issue.

Furthermore, the influence of lifestyle on levels of health and the quality of life of different population groups, including children and adolescents, is widely documented in the literature of health area. ⁸8 . Manzanera D, Montiel-Company JM, Almerich-Silla JM, Gandía JL. Diagnostic agreement in the assessment of orthodontic treatment need using the Dental Aesthetic Index and the Index of Orthodontic Treatment Need. Eur J Orthod . 2010;32(2):193-8. DOI: 10.1093/ejo/cjp084
https://doi.org/10.1093/ejo/cjp084... In this sense, the survey, monitoring and intervention concerning health risk behaviors are considered public health priorities by various health agencies. ³3 . Centers for Disease Control and Prevention. Youth risk behavior surveillance- United States, 2005. MMWR. 2006;55(SS-5).

The results obtained in this study show an association of individual level variables with the severity of malocclusion. Males presented a higher severity of malocclusion compared with females, corroborating other findings in the literature that revealed gender exerted a significant influence on the severity of the disease. ²2 . Carvalho DM, Alves JB, Alves MH. Prevalence of malocclusion in schoolchildren with low socioeconomic status. Rev Gaucha Odontol . 2011;59(1):71-7. ^{, 8}8 . Manzanera D, Montiel-Company JM, Almerich-Silla JM, Gandía JL. Diagnostic agreement in the assessment of orthodontic treatment need using the Dental Aesthetic Index and the Index of Orthodontic Treatment Need. Eur J Orthod . 2010;32(2):193-8. DOI: 10.1093/ejo/cjp084
https://doi.org/10.1093/ejo/cjp084... It is believed that this has happened due to the fact that women are more determined when treating health problems.

There was a higher severity of malocclusion observed in those children who claimed to be less satisfied with their mouth and teeth and feel embarrassed to smile. However, it seems reasonable that self-perception does not coincide with the actual situation of malocclusion, because the problem is not impacting on cultural precepts but seen as an attribute of beauty and masculinity or femininity, as observed in occidental culture. ¹⁹19 . Xiao-Ting L, Tang Y, Huang XL, Wan H, Chen YX. Factors influencing subjective orthodontic treatment need and culture-related differences among Chinese natives and foreign inhabitants. Int J Oral Sci . 2010;2(3):149-57. DOI: 10.4248/IJOS10050
https://doi.org/10.4248/IJOS10050... So the influence of these factors depends on the cultural and social characteristics of each population group.

These findings suggest that, according to the severity of the malocclusion, self-perceived need for orthodontic treatment among children can be predicted. Namely, the self-perception in children should be seen as fundamentally important in understanding the impact of malocclusion on daily life, especially in relation to functional limitations and psychosocial well-being, since it greatly values the physical appearance. ¹⁹19 . Xiao-Ting L, Tang Y, Huang XL, Wan H, Chen YX. Factors influencing subjective orthodontic treatment need and culture-related differences among Chinese natives and foreign inhabitants. Int J Oral Sci . 2010;2(3):149-57. DOI: 10.4248/IJOS10050
https://doi.org/10.4248/IJOS10050...

With regard to access, the results of this study show greater severity of malocclusion in those children who have visited the dentist at least once in their lives. According to Peres et al ¹¹11 . Peres KG, Barros AJD, Anselmi L, Peres MA, Barros FC. Does malocclusion influence the adolescent’s satisfaction with appearance? A cross-sectional study nested in a Brazilian birth cohort. Community Dent Oral Epidemiol . 2008;36(2):137-43. DOI: 10.1111/j.1600-0528.2007.00382.x
https://doi.org/10.1111/j.1600-0528.2007... (2008), there is an increased use of dental services and a reduction in the proportion of people who had never consulted a dentist. Although different health needs cannot be fully eliminated only with the use of health services, they can facilitate qualified access and reduce health inequalities. ¹²12 . Peres KG, Peres MA, Boing AF, Bertoldi AD, Bastos JL, Barros AJD. Redução das desigualdades na utilização de serviços odontológicos no Brasil entre 1998 e 2008. Rev Saude Publica . 2012;46(2):250-9. DOI: 10.1590/S0034-89102012000200007
https://doi.org/10.1590/S0034-8910201200... It is probable that those with access to a dentist usually have a higher need for treatment, including orthodontic.

The results showed that, within the individual context, children in the group with the lowest incomes had a higher severity of malocclusion, corroborating reports in the literature regarding the influence of socioeconomic factors in determining malocclusion. ⁶6 . Doğan AA, Sari E, Uskun E, Sağlam AMŞ. Comparison of orthodontic treatment need by professionals and parents with different socio-demographic characteristics. Eur J Orthod . 2010;32(6):672-6. DOI: 10.1093/ejo/cjp161
https://doi.org/10.1093/ejo/cjp161... ^{, 12}12 . Peres KG, Peres MA, Boing AF, Bertoldi AD, Bastos JL, Barros AJD. Redução das desigualdades na utilização de serviços odontológicos no Brasil entre 1998 e 2008. Rev Saude Publica . 2012;46(2):250-9. DOI: 10.1590/S0034-89102012000200007
https://doi.org/10.1590/S0034-8910201200... ^{, 17}17 . Thomaz EBA, Cangussu MCT, Assis MO. Maternal breastfeeding, parafunctional oral habits and malocclusion in adolescents: A multivariate analysis. Int J Pediatr Otorhinolaryngol . 2012;76(4):500-6. DOI: 10.1016/j.ijporl.2012.01.005
https://doi.org/10.1016/j.ijporl.2012.01...

Using multilevel analysis was due to the importance of investigating interactions between variables on different levels (individual and contextual), which showed greater statistical efficiency, more power and less bias than the one contained in a multivariate analysis as the logistic regression. ⁷7 . Hox JJ. Multilevel analysis: techniques and applications. Mahwah: Lawrence Erlbaum Associates; 2002.

The study highlighted the influence of variables related to the socioeconomic context on the severity of malocclusion. Cities with more families receipients of BF, with lower IDSUS and lower GDP per capita were associated with severe malloclusion. Over the past two decades, social inequalities in health have become, one of the most important issues in public health, both in rich countries and those with medium or low economic income. ¹²12 . Peres KG, Peres MA, Boing AF, Bertoldi AD, Bastos JL, Barros AJD. Redução das desigualdades na utilização de serviços odontológicos no Brasil entre 1998 e 2008. Rev Saude Publica . 2012;46(2):250-9. DOI: 10.1590/S0034-89102012000200007
https://doi.org/10.1590/S0034-8910201200... Some authors have emphasized that the most vulnerable households are more susceptible to malocclusion. ¹⁷17 . Thomaz EBA, Cangussu MCT, Assis MO. Maternal breastfeeding, parafunctional oral habits and malocclusion in adolescents: A multivariate analysis. Int J Pediatr Otorhinolaryngol . 2012;76(4):500-6. DOI: 10.1016/j.ijporl.2012.01.005
https://doi.org/10.1016/j.ijporl.2012.01...

Specifically in relation to malocclusion, Tomita et al ¹⁸18 . Tomita NE, Sheiham A, Bijella VT, Franco LJ. Relação entre determinantes socioeconômicos e hábitos bucais de risco para más-oclusões em pré-escolares. Pesq Odont Bras . 2000;14(2):169-75. DOI: 10.1590/S1517-74912000000200013
https://doi.org/10.1590/S1517-7491200000... (2000) developed a theoretical model that posits the influence of socioeconomic factors on malocclusion through oral habits psychological factors and general patterns of disease. Conceptual models allow us to clarify that socioeconomic factors and access-to-service factors can influence exposure to and development of oral health problems. ¹1 . Ben-Shlomo Y, Kuh D. A life course approach to chronic disease epidemiology conceptual models, empirical challenges and interdisciplinary perspectives. Int J Epidemiol . 2002;3(2):285-93. DOI: 10.1093/ije/31.2.285
https://doi.org/10.1093/ije/31.2.285... ^{, 20}20 . Watt RG. Emerging theories into the social determinants of health: implications for health promotion. Community Dent Oral Epidemiol . 2002;30(4):241-7. DOI: 10.1034/j.1600-0528.2002.300401.x
https://doi.org/10.1034/j.1600-0528.2002...

Although the design of the SBBrasil was robust, the study has some limitations. A weakness of cross-sectional studies is the difficulty in establishing causal relationships based on a cross section of time, limiting confidence in establishing the direction of the association. The design of the study and the evaluation tool used to quantify malocclusion do not identify for how long the individuals surveyed have suffered from the disease.

This information may be helpful in better understanding the role of individual variables and contextual influences concerning malocclusion as an individual, episodic or cyclic condition. Thus, longitudinal studies are needed to allow a better understanding of the association between malocclusion and individual and contextual variables. Another limitation is tooth decay, which was not used in the model due to it being a confounding factor in the study, especially in the question ascertaining whether adolescents have already been to the dentist.

Although there are data available on the prevalence and severity of malocclusion, the sample calculation was based on parameters for dental caries, which is kept as a benchmark as it is among the most significant diseases of the oral cavity. Moreover, it is the only one that has available data for all age groups, and its prevalence and severity generate sample sizes that permit proper inferences for other health problems. ^aaMinistério da Saúde (BR). Secretaria de Vigilância em Saúde. Secretaria de Atenção à Saúde. Coordenação Nacional de Saúde Bucal. SB2010: Pesquisa Nacional de Saúde Bucal. Resultados principais. Brasília (DF); 2011[cited 2012 Feb 08]. Available from: http://dab.saude.gov.br/cnsb/sbbrasil/download.htm

Despite significant advances in recent years in improving health indicators, Brazil is still among the countries with the greatest inequalities, in other words health inequalities between population groups are systematic and significant, but avoidable, unfair and unnecessary. These health inequalities are the product of great inequalities between different social and economic stratum of Brazilian population. ¹¹11 . Peres KG, Barros AJD, Anselmi L, Peres MA, Barros FC. Does malocclusion influence the adolescent’s satisfaction with appearance? A cross-sectional study nested in a Brazilian birth cohort. Community Dent Oral Epidemiol . 2008;36(2):137-43. DOI: 10.1111/j.1600-0528.2007.00382.x
https://doi.org/10.1111/j.1600-0528.2007... The main challenges for the future will be translating existing knowledge and experiences of effective prevention and health promotion programs into strategic action, in order to achieve sustainable advances in oral health, thereby reducing inequalities. ¹³13 . Pertesen PE. The World Oral Health Report, 2003. Continuous improvement of oral health in the 21 st century – the approach of the WHO Global Oral Health Programe. Community Dent Oral Epidemiol . 2003;31Suppl1:3-24.

Based on the contextual variables, it is suggested, therefore, that government incentives could be aimed at cities with the worst SUS structuring and with greater vulnerability, using, for example, the Ministerial Decree no. 718/SAS from 20/12/2010, which differentiates funding for specialized procedures in orthodontics. ^ggMinistério da Saúde (BR). Secretaria de Atenção a Saúde. Portaria nº 718, de 20 de dezembro de 2010. Diario Oficial Uniao. 31 dez 2010 [cited 2012 Apr 23];Seção1:100-3. Available from: http://bvsms.saude.gov.br/bvs/saudelegis/sas/2010/prt0718_20_12_2010.htm l

Identification of risk factors for malocclusion must take into account individual variables together with the contextual variables, building a clearer epidemiological picture capable of planning actions in oral health.

Significant associations between the presence and severity of malocclusion were observed at the individual and contextual level, those being important parameters that can assist in the planning of public policies under the reference of the constitutional principles of comprehensiveness and equity.

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