Social and dental status along the life course and oral health impacts in adolescents: a population-based birth cohort
© Peres et al; licensee BioMed Central Ltd. 2009
Received: 21 August 2009
Accepted: 22 November 2009
Published: 22 November 2009
Harmful social conditions in early life might predispose individuals to dental status which in turn may impact on adolescents' quality of life.
To estimate the prevalence of oral health impacts among 12 yr-old Brazilian adolescents (n = 359) and its association with life course socioeconomic variables, dental status and dental services utilization in a population-based birth cohort in Southern Brazil.
Exploratory variables were collected at birth, at 6 and 12 yr of age. The Oral Impacts on Daily Performances index (OIDP) was collected in adolescence and it was analyzed as a ranked outcome (OIDP from 0 to 9). Unadjusted and adjusted multivariable Poisson regression with robust variance was performed guided by a theoretical determination model.
The response rate was of 94.4% (n = 339). The prevalence of OIDP = 1 was 30.1% (CI95%25.2;35.0) and OIDP ≥ 2 was 28.0% (CI95%23.2;32.8). The most common daily activity affected was eating (44.8%), follow by cleaning the mouth and smiling (15.6%, and 15.0%, respectively). In the final model mother schooling and mother employment status in early cohort participant's life were associated with OIDP in adolescence. As higher untreated dental caries at age 6 and 12 years, and the presence of dental pain, gingival bleeding and incisal crowing in adolescence as higher the OIDP score. On the other hand, dental fluorosis was associated with low OIDP score.
Our findings highlight the importance of adolescent's early life social environmental as mother schooling and mother employment status and the early and later dental status on the adolescent's quality of life regardless family income and use of dental services.
Most clinical and epidemiological studies on oral heath have used clinical parameters as a strategy to evaluate health conditions. However, those parameters only evaluate the physical conditions based on judgments established by professionals - normative assessment - minimizing the psychosocial consequences of the oral conditions . Ideally, the way how individuals perceive and evaluate their health, their symptoms, and consequently their treatment needs, should be included in health surveys. Once the shortcoming of the disease-oriented or biomedical approach has been recognized, the researchers can investigate the impact resulting from the oral health clinical conditions on the quality of life .
A variety of sociodental indicators have been developed and used to overcome the normative assessment, with contributions from psychology, sociology, economics, operational research, and biostatistics [2–4]. Some studies have used general questionnaires to measure oral health impacts in children, such as Oral Impacts on Daily Performance (OIDP) index for adults [5, 6], while other research use specific questionnaire for children . In spite of an increasing number of investigations on the association of dental status with the quality of life in children and adolescents, most of these have addressed specific diseases or conditions, such as orthodontic treatment need [7–9] and dental pain [10, 11]. Moreover, when several dental status were simultaneously investigated, we could not identify any strategy to measure the role of confounders, such as multivariable analysis .
To date, we found only cross-sectional studies which investigated oral health impacts in children and adolescents [5–9], and are unaware of any population-based study in adolescents that uses a prospective study design. This is of concern because a theory formulated by Barker  proposes that there is a critical period of development in early life during which exposures to insults have long-term effects on later health. Moreover, the intensity and duration of exposure to unfavourable or favourable physical and social environments throughout life affects health status in a "dose-response" relationship; it has been termed the "accumulation of risk" hypothesis .
From a life course perspective, it can be hypothesized that children from families with low socio-economic conditions in early life may have less access to (and use of) dental services and a variety of oral hygiene items, and may be more likely to develop harmful oral health behaviours later in life . These might predispose individuals to dental status such as dental caries, gingival bleeding, dental pain, malocclusion in adolescence which in turn may impact on adolescents' quality of life.
The aims of this study were to estimate oral health impacts among 12-yr-old Brazilian adolescents and its association with life course socioeconomic variables, dental status and dental services utilization in a population-based birth cohort in Southern Brazil.
The study was carried out in Pelotas, a city located in the extreme South of Brazil, close to the border with Uruguay. In 2000, it had a population of 323,158. Pelotas has been water fluoridated since 1961, and about 90% of the city's households are covered.
The Pelotas' 1993 birth cohort study
The Pelotas' 1993 birth cohort study (n = 5,249) was developed mainly to evaluate the trends in maternal and child health indicators through a comparison with results of the early 1982 Pelotas birth cohort study, and to assess the associations between early life variables and later outcomes. All the five maternity hospitals in Pelotas were visited daily during 1993 . The questionnaire applied to the mothers at the maternity hospital included questions about social and economic conditions, demography, pregnancy, behavior, health care, and morbidity. The children were weighed, measured, and examined at birth by a team of doctors and medical students. The sub-samples of the cohort were visited at 1, 3, 6, 12 months, and later, at 4 and 11 yr of age. The home visits included questionnaires administered to mother's and children's anthropometric assessments. The details of the methodology have been described elsewhere .
Oral health studies in the 1993 Pelotas Birth cohort at ages 6 and 12 yr
The first Oral Health Study (OHS-6) started in December 1998 as a cross-sectional study nested in the birth cohort. In 1998, a sample of the original cohort, consisting of all low birth-weight children along with a random of 20% of the remainder, was revisited. Among the 1,460 eligible children, 87% (1,270 children) were located. A sub-sample drawn from this group was examined to estimate the prevalence of dental caries , anterior open bite , and posterior cross bite . A sample size of 302 was enough to detect a relative risk of at least 1.3 with 80% power, for a caries prevalence of 65% among the non-exposed, and an error type I of 5%. In the same study, we tested whether breastfeeding acted as a protective factor against the development of malocclusion at age 6 yr . The sample size required to test the association between breastfeeding and malocclusion was estimated for an exposure defined as the duration of breastfeeding of <9 months. Considering the detection of relative risks of at least 1.9 for anterior open bite and 2.5 for posterior cross bite, with a prevalence of 54% and 20%, respectively, in children breastfed for <9 months (exposed), a sample of 342 children was needed to provide 80% power at a significance level of 5%. The sample was inflated by 10% to allow for losses or refusals, resulting in a rounded value of 400 children.
As all of the low-birth-weight children were included in the follow-up at 6 and 12 months of age and at 4 yr of age, they were equally over-represented in the OHS-6 (29.7% when compared with 10% in the original cohort). All the analyses were carried out using weights in other to keep each group proportional to their prevalence in the original sample. The weights used were 0.34 (0.10/0.297) for low birth-weight children and 1.27(0.9/0.703) for the rest. A pilot study involving 40 age-matched children was carried out prior to the fieldwork. All the dental examinations were performed at the child's home by three dentists, responsible for the oral examination, and three interviewers, who administered the questionnaires. The parents were informed about the objectives of the study and consent for interview and examinations were obtained.
Examiner calibration exercises were carried out twice in December 1998 and May 1999. One of the authors was the standard examiner (MAP). Intra- and inter-examiner agreement was high, and the values for the measures of agreement calculated on a tooth-by-tooth basis  were high in the first and second calibration (minimum κ values were 0.81 and 0.75, respectively). The World Health Organization  criteria were used for diagnosing the dental caries. In addition, oral mucosa lesions and the occlusion  were also examined.
The independent variables included child's sex, social and economic conditions, oral behaviors, use of dental services, among others. The response rate was 89.7% (n = 359), and non-responses were mainly owing to families moving out of the city.
All the 359 children who participated in the OHS-6 were visited in their homes in 2005, when the adolescents were 12 yr-old. Before the beginning of the study, a specially trained secretary contacted all the families, and authorization was obtained prior to the interviews and oral examinations. A structured interview including questions about dental services utilization (time since the last visit, type of dental services), dental pain (in the last month and their severity), and oral behaviors (toothbrushing, flossing, topical fluorides utilization) were applied. In addition, a short version of the OIDP  was also administered.
The dental examinations started with the fluorosis diagnosis (WHO 1997), followed by dental trauma  and associated treatments needs, dental caries diagnosis , and gingival bleeding (all the teeth were probed in six sites, and then bleeding was considered after 10 s). In addition, the criteria of the dental aesthetic index (DAI) were adopted for the analysis of specific types of malocclusions and the normative need for orthodontic treatment . Headlamps were used to improve visualization. Each examiner was adequately dressed, and all dental mirrors and CPI probes were previously sterilized.
The questionnaire used was fully tested including the OIDP questions, and a pilot study was carried out with 40 age-matched adolescents who did not participate in the main study. The fieldwork team comprised four pairs of examiners and interviewers. A PhD dental student was the supervisor of the fieldwork team under the orientation of the study coordinators. The calibration was performed on a tooth-by-tooth basis among 40 adolescents aged 11-13 yr enrolled in public and private schools, following the methodology previously described . The examiner reliability was measured using simple and weighted κ statistics (categorical variables) and intra-class correlation coefficients (numeric variables). The minimum value was κ = 0.60 for gingival bleeding, while the vast majority of values were 1.0. A manual with detailed instructions about each aspect of the study was developed and used by the research team during the data collection.
Each home visit ranged between 30 and 40 min. Before leaving the adolescents' house, the interviewer checked the questionnaire. A dental kit with a toothbrush, fluoride toothpaste, and dental floss was given to the adolescent after the visit. The fieldwork supervisor ensured data quality by contacting 10% of the sample by telephone.
A participant was considered lost after four unsuccessful home visits, including at least one at the weekend and one at night. Families who moved out to places no further than 300 kilometers from Pelotas were contacted and invited to participate, to reduce losses. The fieldwork was performed from April to June 2005.
The OIDP was used to assess the adolescent's oral health-related impacts on daily life. The OIDP scale (0-9) is an indicator developed to measure the oral impacts that seriously affect the individual's daily life. The OIDP consists of nine items that cover the physical, psychological, and social dimensions of daily living: eating, smiling, studying, speaking, playing sports, mouth cleaning, sleeping, emotion, and social contact. The adolescents were asked if they had an impact on the nine dimensions of their daily life caused by their mouth or teeth. Each of the nine categories was a binary variable (yes/no). Simple count scores were created by adding the nine dummy variables. We analyzed OIDP as a discrete variable ranged from zero to 9.
The explanatory variables comprised the socioeconomic and demographic characteristics at birth, such as family income (>6, 1.1-6, ≤ 1 Brazilian Minimum Wage), maternal schooling (≥ 9, 5-8, or ≤ 4 yr), maternal employment status at child aged 6 months (no, yes), adolescent skin color (white, black), sex, and family economic status when the child is 12 yr old (A+B, C, and D+E, ANEP - Brazil Criterion for Economic Classification). In addition, the dental status investigated at 6 yr of age as dental caries measured by the dmft index , presence of open bite, and cross bite , and at the age of 12 yr as dental caries through the DMFT , episode of dental pain (last month before the interview), presence of dental trauma , fluorosis , gingival bleeding (% of the number of teeth), and the Dental Aesthetic Index -DAI  components were also included in the analyses. Finally, we considered the use of dental service at the age of 12 yr in the last yr before the interview (routine visit for check-up, treatment, did not attend), and experienced orthodontic treatment until the age of 12 yr (yes/no).
The analyses were performed using STATA 9.0. These included simple sample distribution, sample distribution according to OIDP level and explanatory variables categories. As the OIDP (outcome) was an extent score, the Poisson regression models with robust variance were performed allowing rate ratio estimates.
Consent for interviews and exams were obtained, and both the projects (at the ages of 6 and 12 yr) were approved by the Pelotas Federal University Ethics Committee. Adolescents who presented dental-treatment needs were referred to the Dental Clinic of the Post-Graduate Program in Dentistry of Pelotas Federal University.
Sample distribution of sociodemographic and dental status from birth to 6 yr of age according to OIDP levels (n, %) in adolescents (n = 339) age 12 yr.
OIDP = 0
OIDP = 1
OIDP ≥ 2
Family income at child birth*
Maternal schooling at child birth
≥ 9 yr
5 - 8 yr
Mother employment status at child aged 6 month
Untreated dental caries at age 6
Open bite at age 6 yr
Cross bite at age 6 yr
Sample distribution of current socioeconomic, dental status, and dental visit according to OIDP levels (n, %) in adolescents (n = 339) age 12 yr.
OIDP = 0
OIDP = 1
OIDP ≥ 2
Family economic status at age 12 **
A + B
D + E
Untreated dental caries at age 12
Dental pain at age 12
Dental trauma at age 12
Dental fluorosis at age 12
Gingival bleeding at age 12 (% teeth affected)
Incisal crowding at age 12
Maxillary anterior crowding at age 12
Mandible anterior crowding at age 12
Anterior segment spacing at age 12
Maxillary overjet at age 12
≤ 3 mm
> 3 mm
Anterior open bite at age 12
Dental visit at age 12
Did not attend
Orthodontic treatment until age 12
Simple and multiple Poisson regression analysis of the relationship between socio-demographic and dental status variables according to OIDP (as discrete variable) in adolescents age 12 yr.
Rate Ratio (IC 95%)
Rate Ratio (IC 95%)
Maternal schooling at child birth
≥ 9 yr
5 - 8 yr
Mother employment status at child aged 6 month
Untreated dental caries at age 6
Cross bite at age 6 yr
Family economic status at age 12
A + B
Untreated dental caries at age 12
Dental pain at age 12
Dental fluorosis at age 12
Gingival bleeding at aged 12
<11.5% of teeth
11.5-28.0% of teeth
28.5-92.0% of teeth
Incisal crowding at aged 12
This study investigated the prevalence of the impact of dental status on the day-to-day life in a population-based birth cohort of 12-yr-old adolescents from Pelotas in Southern Brazil, using a life-course approach. A positive association between the cohort partticipant's mother level of education, mother employment status at child early life, beyond the dental status during the life and OIDP was found.
The prevalence of at least one oral impact experienced during the past 6 months by the studied population was high (58.1%), while 28.0% of the cohort participants had two or more impacts. Similar findings for at least one impact were reported among schoolchildren from Uganda (62%) , but not among British adolescents, where the prevalence was only 26.5% . Previous studies carried out in different Brazilian cities found the prevalence of 27.5% and 32.8% [6, 9] of at least one impact.
In our study, the most common daily performances affected by oral health conditions were eating, cleaning of the mouth, and smiling. Eating was also the most frequently affected daily performance observed in Uganda , but executing oral hygiene and smiling was observed to be the main causes of impact in a small town in South Brazil  and London . The aforementioned studies investigated older adolescents than those investigated in this study, and the range of age differences may explain the different results. On the other hand, the epidemiological figures of oral diseases can significantly influence the pattern of the causes of such impacts. For example, early dental pain affected 12.1% and untreated dental caries affected almost half (41.0%) of the adolescents. Therefore, it is understandable that eating have been self-reported as the main impact, corroborating other study developed in Thailand .
It is important to mention that during the protocol development of the oral health study in the Pelotas cohort, the Child-OIDP version  was not yet validated in Brazilian Portuguese. Hence, we used the general OIDP  that was previously validated in a sample of Brazilian adolescents . Studies that investigated the oral health-related quality of life through Child-OIDP index showed the prevalence of overall impact ranging from 15.5% among 11-12-yr-old Peruvian schoolchildren  to 28.6% of Tanzanian schoolchildren aged 12-14 yr , which is much lower than our findings, or on the other hand, much higher (89.8%) than that found in Thai schoolchildren .
Among socioeconomic and demographic variables investigated only those related to the cohort participants mothers - schooling and work status in child early life - were associated with OIDP in adolescence. Level of education is an important marker of socioeconomic position; higher education level generally is predictive of better jobs, higher incomes and better housing and socio-economic position . Consequently, mother's level of education is one of the best predictors for children health, especially in developing countries . In the field of oral health, it is very known that maternal cognitive, behavioral, and psychosocial factors are associated with children oral behaviours as, for example, toothbrushing .
There is a lack of studies addressing the relationship between maternal work, maternal employment status and child oral health. On the other hand, findings from the UK Millennium Cohort Study showed that children whose mothers worked were more likely to primarily drink sweetened beverages between meals, they were likely to eat fruit/vegetables between meals compared to other snacks . The pattern of sugar consumption is strongly associated with dental caries, dental pain and, consequently, impacts on daily life.
Untreated dental caries in both deciduous and permanent dentition was associated with OIDP in adolescence. Dental pain at the age of 12 yr was also strongly associated with OIDP levels, corroborating with another study that showed care-seeking being associated with dental pain, difficulties in sleeping, and difficulties in playing among adolescents [10, 11]. Dental pain in adolescence is a dental public-health concern in Brazil  and worldwide [11, 35], and its assessment can add to the best knowledge of dental-need estimation to achieve one of the Global Goals for Oral Health 2020 . As expected, dental fluorosis was associated with low OIDP score. Having mild fluorosis was significant factor for adolescent's perception of good global rating of oral health .
The impact of malocclusion and orthodontic-treatment needs on OIDP has been deeply investigated [6–9, 29]. In most of these studies, poor oral health-related quality of life were shown in adolescents with self-perceived malocclusion , as well as in those presenting normative orthodontic treatment needs . Hypothetically, malocclusions might have a strong influence on activities, such as smiling, emotion, and social contact. Our results confirm that dentofacial aesthetics play an important role in social interactions and psychosocial well-being. However, it was restricted to incisal crowding, which was also demonstrated in another research . Unlike the other studies, we statistically controlled the impact of different occlusal traits on the OIDP by early life socioeconomic and demographic variables, as well as by the most important oral outcomes.
No difference in the OIDP was found between boys and girls, probably because at this early phase of adolescence, gender-related behaviors are not prominent. We presume that in the subsequent assessment of this cohort in the late adolescence, the differences between boys and girls in health-related quality of life and satisfaction will be revealed, as in another study . Previous studies have shown consistent differences between young males and females in their dental behaviours and pattern of dental attendance, with women generally having more favourable behaviours than men. These gender differences may influence dental status later in life and then, consequently impact of oral health on daily life .
Some important psychosocial variables that possibly act during childhood were not collected in our study. Further studies need to be developed to clarify the complex relationship between social and psychological factors.
Some additional commentaries about the study methods are relevant. The sample investigated at the age of 12 yr did not differ significantly from the original cohort and the 6-yr-old sample. For example, proportion of males (53.9 vs. 53.7%) and family income equal to or lesser than the Brazilian Minimum Wage per month (17.8% vs. 18.1%) observed at 6 and 12 yr of age, respectively, suggest the lack of attrition bias . In addition, high levels of diagnostic reliabilities, the use of blinded examiners/interviewers, knowledge of the prospective factors investigated, as well as a population-based design contribute to the strengths of the study. Measures of oral health-related quality of life have been largely incorporated in oral health surveys to improve the assessment of perceived need and the impact of the outcomes of dental care. In our study, some major methodological improvements were achieved in comparison with the previous reports. First, we analyzed several oral conditions at the same time, including various individual occlusal traits. Second, the simultaneous evaluation of several oral conditions rather than assessing specific outcome was possible with an overview of the dental health needs as well, and consequently, it allowed the prioritization of services planning. Third, it enabled us to verify the impact of early life oral conditions in the adolescent oral health-related quality of life owing to a longitudinal study design. Finally, the use of Poisson regression models instead ordinary logistic regression allowed complete utilization of original OIDP, a ranked data.
The main methodological limitation of the study is the use of general OIDP questionnaire that had been developed for use in adult populations , as the Child-OIDP questionnaire had not been previously validated in Brazil . Moreover, the lack of incidence measures and the need for a larger sample to enhance statistical power are the other limitations of our study.
In conclusion, oral impact on adolescents' day-to-day life was a common finding in our study. We highlighted the importance of adolescent's early life social environmental as mother schooling and mother employment status and dental status that may cause suffering, such as untreated dental caries in both deciduous and permanent dentition, gingival bleeding, and dental pain, besides malocclusion, which is an aesthetical problem. Competing interestsThe authors declare that they have no conflict of interests.
Karen Glazer Peres, Marco Aurélio Peres, Ana MB Menezes, and Pedro Curi Hallal received grants for productivity in research from the CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico). The cohort study is supported by the Wellcome Trust. The initial phases of the cohort study were financed by the European Union, by the PRONEX (Programa de Apoio a Núcleos de Excelência), by the CNPq, and by the Brazilian Ministry of Health.
- Chen MS, Hunter P: Oral health and quality of life in New Zealand: a social perspective. Soc Sci Med 1996, 43: 1213–22. 10.1016/0277-9536(95)00407-6View ArticleGoogle Scholar
- Sheiham A, Spencer J: Health needs assessment. In Pine C. Community Oral Health. Oxford: Wright; 1997:39–54.Google Scholar
- The WhoQol Group: The development of the World Health Organization quality of life assessment instrument (the WHOQOL). In Quality of life assessment: international perspectives. Edited by: Orley J, Kuyken W. Heidelberg: Springer Verlag; 1994:41–60.View ArticleGoogle Scholar
- Gherunpong S, Sheiham A: A sociodental approach to assessing children's oral health needs: integrating an oral health-related quality of life (OHRQoL) measure into oral health service planning. Bull of the World Health Org 2006, 84: 36–42. 10.2471/BLT.05.022517View ArticleGoogle Scholar
- Åstrom AN, Okullo I: Validity and reliability of the Oral Impacts on Daily Performance (OIDP) frequency scale: a cross-sectional study of adolescents in Uganda. BMC Oral Health 2003, 3: 5. 10.1186/1472-6831-3-5View ArticleGoogle Scholar
- De Oliveira , Sheiham A: Orthodontic treatment and its impact on oral health-related quality of life in Brazilian adolescents. J Orthod 2004, 31: 20–7. 10.1179/146531204225011364View ArticleGoogle Scholar
- Gherunpong S, Tsakos G, Sheiham A: A socio-dental approach to assessing children's orthodontic needs. Eur J Orthod 2006, 28: 393–399. 10.1093/ejo/cji114View ArticleGoogle Scholar
- Bernabé E, Sheiham A, De Oliveira CM: Impacts on daily performances attributed to malocclusions by British adolescents. J Oral Rehabil 2009, 36: 26–31. 10.1111/j.1365-2842.2008.01899.xView ArticleGoogle Scholar
- Marques LS, Ramos-Jorge ML, Paiva SM, Pordeus IA: Malocclusion: Esthetic impact and quality of life among Brazilian schoolchildren. Am J Orthod Dentofacial Orthop 2006, 129: 424–427. 10.1016/j.ajodo.2005.11.003View ArticleGoogle Scholar
- GOES PSA, Watt RG, Hardy R, Sheiham A: Impacts of dental pain on daily activities of adolescents aged 14–15 years and their families. Acta Odontol Scand 2007, 66: 7–12. 10.1080/00016350701810633View ArticleGoogle Scholar
- Pau A, Khan SS, Babar MG, Croucher R: Dental pain and care-seeking in 11–14-yr-old adolescents in a low-income country. Eur J Oral Sci 2008, 116: 451–457. 10.1111/j.1600-0722.2008.00563.xView ArticleGoogle Scholar
- Gherunpong S, Tsakos G, Sheiham A: The prevalence and severity of oral impacts on daily performances in Thai primary school children. Health Qual Life Outcomes 2004, 12: 2–57.Google Scholar
- Barker David JP: Mothers, Babies, and Disease in Later Life. London: BMJ Publishing Group; 1994.Google Scholar
- Kuh D, Power C, Blane D, Bartley M: Social pathways between childhood and adult health. In A life course approach to chronic disease epidemiology. Edited by: Kuh D, Ben-Shlomo Y. Oxford: Oxford University Press; 1997:169–198.Google Scholar
- Bastos JL, Peres MA, Peres KG, Araujo CL, Menezes AM: Toothache prevalence and associated factors: a life course study from birth to age 12 yr. Eur J Oral Sci 2008, 116: 458–66. 10.1111/j.1600-0722.2008.00566.xView ArticleGoogle Scholar
- Victora CG, Araújo CLP, Menezes AMB, Hallal PC, Vieira MF, Neutzling MB, Gonçalves H, Valle NC, Lima RC, Anselmi L, Behague D, Gigante D, Barros FC: Methodological aspects of the 1993 Pelotas (Brazil) Birth Cohort Study. Rev Saúde Publica 2006, 40: 39–46.Google Scholar
- Peres MA, Latorre MRDO, Sheiham A, Peres KG, Barros FC, Fernandez PG, Maas AMN, Romano AR, Victora CG: Social and biological early life influences on severity dental caries in children aged 6. Community Dent Oral Epidemiol 2005, 33: 53–63. 10.1111/j.1600-0528.2004.00197.xView ArticleGoogle Scholar
- Peres KG, Latorre MRDO, Sheiham A, Peres MA, Victora CG, Barros FC: Social and biological early life influences on the prevalence of open bite in Brazilians yr-olds. Int J Paediatr Dent 2007, 17: 41–49. 10.1111/j.1365-263X.2006.00793.xView ArticleGoogle Scholar
- Peres KG, Barros AJD, Peres MA, Victora CG: Effects of breastfeeding and sucking habits on malocclusion in a birth cohort study. Rev Saúde Pública 2007, 41: 343–350.View ArticleGoogle Scholar
- Peres MA, Traebert JL, Marcenes W: Calibration of examiners for dental caries epidemiology studies. Cad Saúde Pública 2001, 17: 153–159. 10.1590/S0102-311X2001000100016View ArticleGoogle Scholar
- WHO: Oral health surveys: basic methods. 4th edition. Geneva: WHO; 1997.Google Scholar
- Foster TD, Hamilton MC: Occlusion in the primary dentition. Study of children at 2 and one-half to 3 yr of age. Br Dent J 1969, 126: 76–79.Google Scholar
- Adulyanon S, Vourapukjaru J, Sheiham A: Oral impacts affecting daily performance in a low dental disease Thai population. Community Dent Oral Epidemiol 1996, 24: 385–389. 10.1111/j.1600-0528.1996.tb00884.xView ArticleGoogle Scholar
- O'Brien M: Children's dental health in the United Kingdom 1993. Report of dental survey, office of population censuses and surveys. London: Her Majesty's Stationary Office; 1994.Google Scholar
- Victora CG, Huttly SR, Fuchs SC, Olinto AMT: The role of conceptual frameworks in epidemiological analysis: a hierarchical approach. Int J Epidemiol 1997, 26: 224–227. 10.1093/ije/26.1.224View ArticleGoogle Scholar
- Michel-Crosato E, Biazevic MG, Crosato E: Relationship between dental fluorosis and quality of life: a population based study. Braz Oral Res 2005, 19: 150–155. 10.1590/S1806-83242005000200014View ArticleGoogle Scholar
- Gherunpong S, Tsakos G, Sheiham A: Developing and evaluating an oral health-related quality of life index for children; the CHILD-OIDP. Community Dent Health 2004, 21: 161–169.Google Scholar
- Goes PSA: The prevalence and impact of dental pain in Brazilian schoolchildren and their families, PhD Thesis. Department of Epidemiology and Public Health, University College London, University of London; 2001.Google Scholar
- Bernabé E, Flores-Mir C, Sheiham A: Prevalence, intensity and extent of Oral Impacts on Daily Performances associated with self-perceived malocclusion in 11–12-yr-old children. BMC Oral Health 2007, 7: 1–7. 10.1186/1472-6831-7-6View ArticleGoogle Scholar
- Mtaya M, Astrom AN, Tsakos G: Applicability of an abbreviated version of the Child-OIDP inventory among primary schoolchildren in Tanzania. Health Qual Life Outcomes 2007, 5: 40. 10.1186/1477-7525-5-40View ArticleGoogle Scholar
- Lynch J, Kaplan G: Socio economic position. In Social Epidemiology. Edited by: Berkman LF, Kawachi I. New York: Oxford Press; 2000:13–35.Google Scholar
- Victora CG, Huttly SRA, Barros FC, Lombardi C, Vaughan JP: Maternal education in relation to early and late child health outcomes: findings from a Brazilian cohort study. Soc Sci Med 1992, 34: 899–905. 10.1016/0277-9536(92)90258-RView ArticleGoogle Scholar
- Finlayson TL, Siefert K, Ismail AI, Sohn W: Maternal self- efficacy and 1–5 year-old children's brushing habits. Community Dent Oral Epidemiol 2007, 35: 272–81. 10.1111/j.1600-0528.2007.00313.xView ArticleGoogle Scholar
- Hawkins SS, Cole TJ, Law C: Examining the relationship between maternal employment and health behaviours in 5-year-old British children. J Epidemiol Community Health 2009, in press.Google Scholar
- Jiang H, Petersen PE, Peng B, Tai B, Bian Z: Self-assessed dental health, oral health practices, and general health behaviors in Chinese urban adolescents. Acta Odontol Scand 2005, 63: 343–352. 10.1080/00016350500216982View ArticleGoogle Scholar
- Hobdell M, Petersen PE, Clarkson J, Johnson N: Global goals for oral health 2020. Int Dent J 2003, 53: 285–288.View ArticleGoogle Scholar
- Do LG, Spencer A: Oral health-related quality of life of children by dental caries and fluorosis experience. J Public Health Dent 2007, 67: 132–9. 10.1111/j.1752-7325.2007.00036.xView ArticleGoogle Scholar
- 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: 137–143. 10.1111/j.1600-0528.2007.00382.xView ArticleGoogle Scholar
- Maes L, Vereecken C, Vanobbergen J, Honkala S: Tooth brushing and social characteristics of families in 32 countries. Int Dent J 2006, 56: 159–67.Google Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.