Maternal education is an independent determinant of cariogenic feeding practices in the first year of life.
Abstract: AIM: To identify risk factors for cariogenic feeding practices in the first year of life. STUDY DESIGN: Cohort study. METHODS: 500 children born within the public health care system in Sao Leopoldo, Brazil, were recruited in a follow-up program. Anthropometric and demographic data were collected soon after birth; data on feeding practices were assessed at 12 months of age using a standardised questionnaire; clinical examination at 4 years of age allowed identification of cariogenic feeding practices in the first year of life and to quantify their relative risks. In the present study, the attributable risks of each child were summed, and the outcome was assessed for the upper quartile of scores for cariogenic feeding practices. STATISTICS: Adjusted relative risks for the outcome were estimated using robust Poisson regression models. RESULTS: A total of 327 children comprised the final study sample, i.e. were followed from birth to 4 years of age. Multivariate analysis showed that the risk of cariogenic feeding practices doubled in children from mothers with less than 5 years of education (RR 2.19, 95%CI 1.26-3.82) and was 70% higher in children from mothers with 5-8 years of education when compared with maternal education >8 years. The other independent variables were not associated with the outcome. CONCLUSIONS: Low maternal education is a risk factor for cariogenic feeding practices, independently of other factors. Mothers with low educational levels should be the focus of child health promotion interventions, especially those aimed at controlling dental caries.

Key words: Dental caries; risk factors; feeding behaviour; diet, cariogenic
Article Type: Report
Subject: Dental caries (Risk factors)
Dental caries (Demographic aspects)
Dental caries (Reports)
Authors: Feldens, C.A.
Kramer, P.F.
Sequeira, M.C.
Rodrigues, P.H.
Vitolo, M.R.
Pub Date: 04/01/2012
Publication: Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 European Academy of Paediatric Dentistry ISSN: 1818-6300
Issue: Date: April, 2012 Source Volume: 13 Source Issue: 2
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: Brazil Geographic Code: 3BRAZ Brazil
Accession Number: 290066486
Full Text: Introduction

Childhood caries is a public health problem worldwide, leading to pain, chewing difficulties, speech and psychological problems [Pine et al., 2004; Watt, 2005; Finlayson et al., 2007; Petersen, 2009]. There is recent evidence of the negative impact of childhood caries on oral health-related quality of life of preschool children and their parents [Abanto et al., 2011].

The development of strategies to reduce and control childhood caries requires clarification about the complex web of factors that contribute to the disease. Although cariogenic feeding practices represent a necessary condition for the occurrence of caries [Ismail, 1998; Thitasomakul et al., 2009; Feldens et al., 2010a; Johansson et al., 2010; Hashim et al., 2011], few studies have explored the onset of such relationships. Improving our knowledge on the characteristics of groups more likely to adopt dietary habits associated with dental caries, with a focus on demographic, socio-economic, health and health care data, is extremely important for the development and implementation of cost-effective preventive strategies [Watt, 2005].

Therefore, the objective of this study was to identify risk factors associated with cariogenic feeding practices in the first year of life of children born in the municipality of Sao Leopoldo, southern Brazil. The study hypothesis was that some demographic, socio-economic and anthropometric characteristics would have an influence on cariogenic feeding practices in the first year of life.

Methods

Study design and population. This cohort study was a clinical trial designed to assess the effectiveness of the implementation of the "Ten steps for the healthy feeding of children younger than two years," an initiative of the Brazilian Ministry of Health and the Pan American Health Organization (clinical trial registration number NCT00635453) [Brazil, 2011].

Subjects were recruited among babies born in the public health care system of Sao Leopoldo, southern Brazil, from October 2001 to June 2002. Following birth, mothers of full-term newborns ([greater than or equal to] 37 weeks) with no contraindications for breastfeeding (i.e. HIV/AIDS), whose children presented normal birth weight ([greater than or equal to] 2,500 g) and no congenital malformations were invited to participate in the study.

The sample size was calculated based on the aim of the major study: to detect a difference of 35% in the occurrence of dental caries between the intervention and control groups at 4 years of age. Considering a significance level of 95%, 80% power, a non-exposed vs. exposed ratio of 3:2 and a prevalence of 48% of caries at 4 years of age [Ferreira et al., 2007] the minimum required sample size was 300 children.

Ethics. The study was approved by the Research Ethics Committee of the Federal University of Rio Grande do Sul. One parent of each child provided written informed consent prior to inclusion in the study. All children received routine care by their paediatricians. At the assessment conducted at 4 years of age, children diagnosed with caries were referred for treatment. Overweight, failure to thrive or stunted children, children with anaemia, and those presenting developmental problems were also referred to their primary care doctors.

Data collection. Undergraduate students studying nutrition conducted face-to-face structured interviews with the mothers of children after birth and at 6 and 12 months postpartum.

Demographic characteristics (newborn's sex, mother's age, and birth order) and anthropometric data (birth weight and length, categorised into lower decile, P10-P90, and upper decile) were collected after birth.

At 6 months of age, socio-economic data were collected: maternal education in years, paternal occupational status, family income, and number of prenatal care visits, categorised as adequate ([greater than or equal to] 6 visits) and inadequate (<6 visits) [Brazil, 2000]. Monthly family income was categorised into lower decile (<$USA Dollars 100.00), P10-P90 ($USA Dollars 100.00 to $USA Dollars 400.00), and upper decile (>$USA Dollars 400.00).

When the children were 12 months old, dietary behaviour variables were assessed using a standardised questionnaire: duration of total and exclusive breastfeeding, breastfeeding frequency, bottle feeding at night and bottles for juices, teas, and soft drinks, number of meals and snacks, and fruit and vegetable intake. Mothers were also asked about the intake of foods with a high density of sugar and lipids (yes/ no question). High density of sugar was defined as >50% of simple carbohydrates in 100 g of food (e.g. candies, soft drinks, sugar, and honey), whereas high density of lipids was regarded as >30% of fat content in 100 g of food (e.g. salty snacks, filled cookies, and chocolate) [Drewnowski, 2005]. Finally, data on the occurrence of any type of infection and hospitalisation over the preceding 6 months (i.e. between 6 and 12 months of age) were also collected.

At 4 years of age, data on each child's oral health were collected during clinical dental examination. All children were screened for the presence of carious lesions by a calibrated dental surgeon (kappa=0.90) at a municipal health centre. The number of decayed, missing/extracted, and filled teeth (dmft index) was recorded, and severe early childhood caries (ECC) was diagnosed according to the National Institutes of Health (USA) case definition [Drury et al., 1999]: [greater than or equal to]1 decayed, missing or filled smooth surfaces in primary maxillary anterior teeth, or [greater than or equal to] 5 decayed (d1+), missing or filled surfaces (dmfs)

Clinical examinations at 4 years of age allowed identification of the following feeding practices in the first year of life associated with severe early childhood caries: high frequency of breastfeeding at 12 months (relative risk, RR=2.00), use of feeding bottle for juices, teas, and soft drinks in the first year of life (RR=1.41), high frequency of food consumption (number of daily meals and snacks >8) at 12 months (RR=1.42), and consumption of foods with high density of sugar in the first year of life (RR=1.43) [Feldens et al., 2010a]. The attributable risk of these feeding practices, defined as the additional risk of developing a condition after being exposed to a given factor when compared with non-exposed subjects [Fletcher and Fletcher, 2005], is presented in Table 1.

In the present study, the attributable risks of each child were summed, resulting in scores ranging from zero (no cariogenic feeding practices) to 226 (all cariogenic feeding practices). The upper quartile of these scores represented the outcome of this study, suggestive of the presence of more cariogenic feeding practices.

Statistical analysis. Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS), version 16.0. First, comparisons between categories of independent variables regarding cariogenic feeding practices were performed using the chi-square test. Second, unadjusted and adjusted relative risks for cariogenic feeding practices were estimated using robust Poisson regression models. Relative risks and 95% confidence intervals (95%CI) were estimated separately for each variable.

Multivariable analysis was also performed, starting with all available risk factors and confounders using backward elimination if Wald p value was >0.05. The only exception was the variable that represented the intervention (child's group status) which remained in the models as a possible confounder regardless of its statistical significance.

Results

Among the 500, complete data on feeding practices at 12 months and on the presence of severe early childhood caries at 4 years were obtained for 327 children, who comprised the final sample. Child age ranged from 12-16 months at the assessment of feeding practices; at the dental examination, child age varied from 48-53 months (mean=50.5; standard deviation, SD [+ or -] 1.7). There was a similar distribution of male and female children in the sample. Maternal education ranged from 1-13 years, with a mean [+ or -] SD of 6.9 [+ or -] 2.7 years; per capita income was above 1 monthly Brazilian minimum wage (about $USA Dollars 80.00) in only 18% of the families.

The calculation of scores of attributable risk revealed that 52 (15.9%) children did not present any cariogenic experience at 12 months of age (attributable risk = zero). However 88 children (26.9%) presented an attributable risk score above 126, representing the upper quartile of cariogenic feeding practices (Table 2).

Table 3 shows that there was no difference between male and female children regarding cariogenic feeding practices (p=0.672). Conversely, maternal education was significantly associated with the outcome (p=0.008). The higher the level of maternal education, the lower the prevalence of cariogenic feeding practices: 35.5% among children of mothers who had <5 years of education, 29.2% among those who had between 5- 8 years, and 17.0% for mothers who had >8 years of education. Similarly, the prevalence of cariogenic feeding practices decreased significantly as family income increased (p=0.021), as follows: 43.8% in the lower decile vs. 18.2% in the upper decile of monthly family income. The other variables assessed did not show significant associations with the outcome.

In the crude model, both maternal education and family income were statistically associated with cariogenic feeding practices (Table 4). The final model showed that the risk of cariogenic feeding practices was more than twice that for maternal education below 5 years and 70% higher among children whose mothers had between 5-8 years of education. Conversely, family income lost significance after adjustment for confounding factors. None of the other independent variables assessed was maintained in the multivariate analysis.

Discussion

The main result found in the present study was the independent effect of maternal education on cariogenic feeding practices. Although several studies available in the international literature have indicated the presence of an important causal relationship between childhood health outcomes and socio-economic variables, particularly maternal education, little is known about the precise mechanisms by which maternal education protects the child [Finlayson et al., 2007; Declerck et al., 2008]. The present study adds to the existing body of knowledge by possibly shedding some light on one of such mechanisms, namely feeding practices in general and cariogenic feeding practices in particular.

Overall, the dietary choices of children, and even their individual taste predispositions, are strongly influenced by what is offered to them by their parents or guardians [Birch, 1998].

The results of the present study suggest that the consumption of cariogenic foods is not influenced by purchasing power, once family income was not associated with the outcome in the final model. Conversely, maternal education was identified as the only factor significantly associated with cariogenic feeding practices among other variables commonly investigated in studies involving children's health, such as anthropometric characteristics, use of health care services, and child's overall health.

Mothers are usually more directly involved than fathers in child care, especially feeding, in the first five years of life of the child [Reisine and Douglass, 1998; Rossow et al., 1990; Birch, 1998; Skinner et al., 2002]. It is therefore possible that higher maternal education results in better child care patterns. A limited offer of sweets to children from mothers with higher educational levels has been previously reported for Norwegian children [Rossow et al., 1990]. On the other hand, it is also possible that maternal characteristics not investigated in the present study, such as self-esteem and depressive symptoms, may represent an additional explanation for the fact that mothers with lower educational levels offer more cariogenic foods to their children [Willems et al., 2005; Finlayson et al., 2007].

Some characteristics of the present study indicate a possible causal relationship, rather than a simple association, between maternal education and cariogenic feeding practices. In this sense, three aspects deserve special mention: (a) the temporal relation between the exposure (maternal education) and the outcome (cariogenic feeding practices), with the former preceding the latter; (b) plausibility, once it is expected that a higher level of education will provide the mother with an improved ability to protect her child against different conditions; (c) a dose-response relationship, i.e. the higher the level of exposure, the higher the risk of presenting the outcome. Unfortunately, however, comparisons between the present findings and those already published in the literature are difficult to accomplish in view of the scarcity of studies designed to investigate risk factors associated with feeding practices known to be cariogenic in childhood.

The main limitation of the present study was the relatively high number of patients lost to follow-up between child birth and the assessment performed at 4 years of age. Our losses, largely due to families moving to an unknown address, are similar to many other household-based studies involving follow-up of young adults living in low-income, large, urban areas of developing countries. Taking into consideration the sensitivity analysis previously reported [Feldens et al., 2010a] the authors believe that the rate of patients lost to follow-up has not influenced the final results. Another aspect that merits discussion is that the outcome was measured using the scores of cariogenic feeding practices obtained in a single study. However, it is important to emphasise that the cariogenic potential of such practices has been previously described in children from different communities worldwide, under real conditions [Jin et al., 2003; Harris et al., 2004; van Palenstein Helderman et al., 2006; Thitasomakul et al., 2009; Johansson et al., 2010].

Among the main clinical implications of our findings, it is possible to emphasise the importance of prioritising mothers with low education levels in the planning and implementation of child health promotion interventions. Mothers should receive adequate guidance starting in pregnancy, with a focus on healthy feeding practices and child protection against several diet-related chronic diseases, including dental caries. Our previous results had shown that prolonged breastfeeding once or twice a day was not a risk factor for dental caries [Feldens et al., 2010a]. However, breast feeding several times a day at 12 months represented a risk factor for ECC, even after adjustment for other dietary practices. For this reason, the attributable risk of this variable was used to compose the outcome in the current analysis. Guidelines on child health should take into account the negative impact of a high frequency of breastfeeding at 12 months of age and other cariogenic practices on childhood oral health.

Trials published in the last decade have demonstrated that providing fluoride toothpaste, professionally using fluoride early in childhood, as well as providing advice to parents on hygiene practices, reduce the incidence of ECC [Davies et al., 2002; Weinstein et al., 2006; Lawrence et al., 2008; Plutzer and Spencer, 2008]. Incorporating such specific measures will potentially improve oral health and reduce inequalities in high-risk communities [Mohebbi et al., 2009]. In the first years of life of their children, mothers are particularly receptive to guidance on healthy practices; this includes mothers from families of a low socio-economic status [Feldens et al., 2010b]. In addition, it is expected that investments aimed at improving the educational level of the population may indirectly protect children against different conditions.

The results of the present study can be generalised to other children of similar socio-economic status, i.e. to all families that typically seek treatment at public health care facilities and who often face difficulties in gaining access to dental care. Further studies should be conducted to clarify the role of psycho-social variables, such as self-esteem and depressive symptoms, in the assessment of maternal education. Qualitative investigations could also be conducted to clarify why less educated mothers employ more cariogenic practices. Finally, the limited number of trials evaluating the impact of improving mother's knowledge on feeding practices, especially in the early years of the child's life, underscores the need for further research into this topic in different settings.

Conclusions

Low maternal education is a risk factor for cariogenic feeding practices in the first year of life and represents one of the possible mechanisms by which lower socio-economic status is related with dental caries.

Cariogenic feeding practices were not influenced by family income or by demographic, anthropometric, and child's health characteristics.

Mothers with lower educational levels should be the focus of child health promotion interventions, especially those aimed at controlling dental caries.

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C.A. Feldens *, P.F. Kramer *, M.C. Sequeira *, P.H. Rodrigues *, M.R. Vitolo **

* Department of Paediatric Dentistry, Luterana University of Brasil (ULBRA). Canoas. ** Department of Nutrition, Federal University of Ciencias da Saude de Porto Alegre. Porto Alegre, Brazil

Postal address: C.A. Feldens, Rua Joao Telles 185/1301, Porto Alegre, RS. ZIP Code 90.035.121, Brazil.

Email: cafeldens@terra.com.br
Table 1--Cariogenic feeding practices in the first year of life and
association with severe early childhood caries at 4 years of age

                                                    Attributable
Cariogenic feeding practices        Relative risk     risk (%)

Daily breastfeeding frequency           2.00          (100.0)
at 12 months [greater than
or equal to] 3

Number of daily meals and               1.42           (42.0)
snacks at 12 months > 8

Bottle use for fruit juices/soft        1.41           (41.0)
drinks at 12 months

High density of sugar at                1.43           (43.0)
12 months

Table 2--Simple (n) and relative (%) frequency of children in the
different quartiles of scores obtained according to the attributable
risk of cariogenic feeding practices

Combined attributable
risk scores (sum of individual    n      (%)
attributable risks)

1st quartile (<42)                89     27.1
2nd quartile (42-84)              75     23.0
3rd quartile (85-126)             75     23.0
4th quartile (>126)               88     26.9
Total                            327    100.0

Table 3--Simple (n) and relative (%) frequency of Brazilian children
with cariogenic feeding practices according to demographic,
socio-economic, and anthropometric data

                       Cariogenic feeding practices
Variables        N          (upper quartile)

                        n      (%)       p

Total           327    88    (26.9)

Sex                                    0.672
  Male          192    50    (26.0)
  Female        135    38    (28.1)

Maternal education (years)             0.008
  < 5            62    22    (35.5)
  5-8           171    50    (29.2)
  > 8            94    16    (17.0)

Number of prenatal care visits         0.366
  Inadequate     92    28    (30.4)
  Adequate      220    56    (25.5)

Maternal age at delivery (years)       0.534
  < 18           33    10    (30.3)
  18-35         264    71    (26.9)
  > 35           30     7    (23.3)

Paternal occupational status           0.861
  Unemployed     30     7    (23.3)
  Informal      124    35    (28.2)
  employment
  Formal        144    40    (27.8)
  employment

Family income (minimum wages)          0.021
  < P10          32    14    (43.8)
  P10-P90       254    67    (26.4)
  > P90          33     6    (18.2)

First child                            0.100
  Yes           128    28    (21.9)
  No            199    60    (30.2)

Birth weight                           0.545
  < P10          34     9    (26.5)
  P10-P90       254    67    (26.4)
  > P90          34    12    (35.3)

Birth length                           0.490
  < P10          43    15    (34.9)
  P10-P90       214    56    (26.2)
  > P90          65    17    (26.2)

Infection at 6-12 months of age        0.682
  Yes            86    22    (25.6)
  No            215    60    (27.9)

Hospitalisation at 6-12 months of age  0.100
  Yes            21     6    (28.6)
  No            306    82    (26.8)

Table 4--Crude and adjusted relative risks and 95% confidence
intervals for the presence of cariogenic feeding practices according
to different variables

Total                                RR * (95%CI)        p

Sex                                                    0.672
  Male                                   1.00
  Female                           1.08 (0.75-1.55)

Maternal education (years)                             0.033
  <5                               2.08 (1.19-3.64)
  5-8                              1.72 (1.04-2.84)
  >8                                     1.00

Number of prenatal care visits                         0.362
  Inadequate                       1.20 (0.81-1.75)
  Adequate                               1.00

Maternal age at delivery (years)                       0.824
  <18                              1.30 (0.57-2.98)
  18-35                            1.15 (0.58-2.27)
  >35                                    1.00

Paternal occupational status                           0.868
  Unemployed                       0.84 (0.42-1.69)
  Informal employment              1.02 (0.69-1.49)
  Formal employment                      1.00

Family income (minimum wages)                          0.037
  P90                                   1.00

First child                                            0.107
  Yes                                    1.00
  No                               1.38 (0.93-2.04)

Birth weight                                           0.513
  P90                             1.33 (0.65-2.73)

Birth length                                           0.461
  P90                                   1.00

Infection at 6-12 months of age                        0.684
  Yes                              0.92 (0.60-1.39)
  No                                     1.00

Hospitalisation at 6-12 months of age                  0.858

  Yes                              1.07 (0.53-2.15)
  No                                     1.00

Total                               RR ** (95%CI)       p

Sex
  Male                                    NS
  Female

Maternal education (years)
  <5                               2.19 (1.26-3.82)   0.005
  5-8                              1.70 1.03-2.81)    0.037
  >8                                     1.00

Number of prenatal care visits
  Inadequate                              NS
  Adequate

Maternal age at delivery (years)
  <18                                     NS
  18-35
  >35

Paternal occupational status
  Unemployed                              NS
  Informal employment
  Formal employment

Family income (minimum wages)
  P90

First child
  Yes                                     NS
  No

Birth weight
  P90

Birth length
  P90

Infection at 6-12 months of age
  Yes                                     NS
  No

Hospitalisation at 6-12 months of age
  Yes                                     NS
  No

* Crude relative risk (RR) "Relative risk adjusted for child's group
status (intervention or control group); NS=non-significant (variable
not included in the final model)
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