dmfs and BMI in pre-school Greek children. An epidemiological study.
AIM: This was to investigate the relationship between dental caries
(dmfs) and body mass index (BMI) categories in 3-5.5 year old children
in Thessaloniki, Greece. METHODS: The study was conducted in 18
municipal day care centres and involved 361 children. The dmfs was
determined on site by one calibrated examiner using disposable dental
mirrors and a penlight. The height and weight of the children were
measured on site by a nutritionist, who grouped them into four BMI
categories. STATISTICS: The estimation of the relationship between the
BMI and dmfs values was based on a generalised linear model (Poisson
log-linear regression) while the sequential Bonferroni method was used
for pair-wise comparisons between BMI categories. RESULTS: Mean dmfs
values for each BMI category were: 1.02 (SD [+ or -] 2.41) for the
underweight (n=44), 0.74 (SD [+ or -] 2.24) for the normal weight
(n=281), 1.88 (SD [+ or -] 4.28) for the overweight (n=26) and 0.80 (SD
[+ or -] 2.53) for the obese (n=10). Overweight children were found to
show statistically significant differences in dmfs values compared with
both children of normal weight (p<0.001) and those underweight
(p=0.015). CONCLUSION: Overweight Greek pre-school children are at
higher risk of dental caries.
Key words: Body mass index, dental caries, preschool children
Parent and child
Body mass index (Measurement)
Body mass index (Physiological aspects)
Dental caries (Risk factors)
Dental caries (Demographic aspects)
Elementary school students (Health aspects)
|Publication:||Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2011 European Academy of Paediatric Dentistry ISSN: 1818-6300|
|Issue:||Date: June, 2011 Source Volume: 12 Source Issue: 3|
|Product:||Product Code: E197200 Students, Elementary|
|Geographic:||Geographic Scope: Greece Geographic Code: 4EUGR Greece|
Early childhood caries (ECC) is the most common chronic disease in pre-school age children. ECC is the presence of one or more carious teeth in a child not having completed the sixth year of age [Vadiakas, 2008; AAPD, 2010]. Epidemiological data reveal the high prevalence of the disease in pre-school age children such as 55.4% in Scotland [Pitts et al., 2005], 42.8% in Greece [Oulis et al., 2005], 39.6% in England and Wales [Pitts et al., 2005], 38.9% in Norway [Haugejorden et al., 2002], 29.0% in Denmark [Poulsen et al., 2002] and 42% in the U.S.A. [Hong et al., 2008].
Pre-school children with body mass index (BMI) values below normal are characterised as underweight. They are more numerous in developing countries of Africa, Asia and Latin America where the percentage under weight can reach 32% [Black et al., 2008]. In developed countries this percentage is much lower: in Germany 3.8% (3-6 years) [Kurth and Schaffrath Rosario, 2007], in the Netherlands 1.5-3.6% (2-6 years) [van Buuren, 2004], in Belgium 4.1% (3.4-14.8 years) [van Gysel et al., 2009], in Greece 13% (3-12 years) [Kontogianni et al., 2010] and in the U.S.A. 4% (2-6 years) [Hong et al., 2008]. On the other hand, BMI values above normal characterise a child as overweight or obese. Percentages for overweight and obese pre-school children grouped together are 11.9% in the Czech Republic (4 years) [Vignerova and Blaha, 2007], 15% in the Netherlands (4 years) [van den Hurk et al., 2007], 27.5% in Ireland (4 years) [Whelton et al., 2007], 21.3% in Greece (1-5 years) [Manios et al., 2007] and 22% in the United States (2-6 years) [Hong et al., 2008].
Dental caries and deviations from normal weight are two conditions which share several broadly predisposing factors such as genetics, diet, socio-economic status, lifestyle and other environmental factors. Their possible association may be complex and the reported findings in pre-school children remain controversial. For example, such an association was found in one Mexican study [Vazquez-Nava et al., 2010] and in part (60-72 month age group) in a study in the United States of America [Hong et al., 2008], and was absent in two U.S.A., one Chinese and one Brazilian studies [Chen et al., 1998; Macek and Mitola, 2006; Granville-Garcia et al., 2008; Kopycka-Kedzierawski et al., 2008].
The aim of the present study was to assess the relationship between dental caries and body mass index (BMI) in preschoolers in the municipality of Thessaloniki.
The study was conducted in 18 municipal day care centres of Thessaloniki, Greece. All 361 healthy (ASA I, II) children (183 boys, 178 girls) aged between 3 and 5.5 years (mean [+ or -] SD = 4.0 [+ or -] 0.8) that were present at the designated centre on the examination day were included.
The dental examinations were performed on site by one calibrated examiner (VB) using disposable dental mirrors and a penlight. World Health Organisation criteria were used for scoring dental caries [WHO, 1997] using the dmfs index. Carious enamel opacities were not included. Anthropometric measurements were performed by a nutritionist. The children wore light clothing and no shoes. A portable measuring unit and a digital scale were used for measuring height and weight respectively. The children were divided into four categories based on BMI results: underweight, normal weight, overweight and obese. BMI values were calculated according to the formula weight/height in kg/[m.sup.2] and compared with international, gender and age adjusted cut off points for underweight (thinness) (<18.5kg/[m.sup.2] at age 18), overweight (>25kg/[m.sup.2] at age 18) and obesity (>30kg/[m.sup.2] at age 18) [Cole et al., 2000; Cole et al., 2007].
Statistical methods. Intra-examiner agreement for dmfs assessment was estimated after a random examination of about 10% of the children with Kendall's tau_b=0.99. The estimation of the relationship between BMI and dmfs values was based on a generalized linear model (GLM, over dispersed Poisson regression), while the sequential Bonferroni method was used for the comparison of the estimated dmfs marginal means between BMI categories [Norusis, 2008]. The analysis was performed with the SPSS 16.0 package and the level of significance was set at p<0.05.
Child numbers and gender per BMI category. The percentage distribution according to each of the four BMI categories was: 77.8% normal in weight, 12.2% underweight, 7.2% overweight and 2.8% obese. The actual numbers in relation to gender appear in Figure 1. In total, 22.2% of our sample had BMI values that deviated from normal levels.
[FIGURE 1 OMITTED]
Mean dmfs values per BMI category. From the total population sample, 20.2% (73/361) of the children had dmfs of 1 or more, that is, 79.8% were caries-free. Mean dmfs values for each BMI category were: 1.02 (SD [+ or -] 2.41) for the underweight, 0.74 (SD [+ or -] 2.24) for the normal in weight, 1.88 (SD [+ or -] 4.28) for the overweight and 0.80 (SD [+ or -] 2.53) for the obese (Figure 2). The percentiles of dmfs per each BMI category revealed skewed distributions (Table 1). At the 50th percentile of all cases the dmfs median values were zero. Even at the 75th percentile, normal and obese categories had dmfs values equal to zero, while overweight had a value equal to 1.25. At the extremes (90th percentile) of the distributions the differences between overweight, underweight and normal were obvious (8.20, 5.00 and 2.00 respectively).
The relationship between BMI categories and dmfs values. A statistically significant association between the BMI variable and dmfs values was found (likelihood ratio chi-square (df=3) = 29.552, p<0.001). Regarding caries level, overweight children were found to have statistically significantly larger dmfs values than children of normal weight (EXP (model coefficient) = 2.5, 95% CI: 1.9-3.5, p<0.001, after sequential Bonferroni test) as well as larger values than underweight children (EXP (model coefficient) = 1.84, 95% CI: 1.23-2.77, p=0.015, after sequential Bonferroni test). The differences between obese children and any other BMI category were not significant (p>0.05).
[FIGURE 2 OMITTED]
Comparison of caries and BMI with other studies. The percentage of children with caries (20.2% for mean age 4 years) was found to be low in comparison with other epidemiological surveys mentioned above, ranging from 29% in Denmark to 55.4% in Scotland [Poulsen et al., 2002; Pitts et al., 2005]. In the present study, 10% (36/361) of the children examined had BMI values above normal. This percentage is low compared with epidemiological data for pre-school children in Greece, Czech Republic, Netherlands, Ireland and in the U.S.A. [Manios et al., 2007; van den Hurk et al., 2007; Vignerova and Blaha, 2007; Whelton et al., 2007; Hong et al., 2008]. The 12.2% of underweight children in the present study agrees with a previous Greek study, which, however, involved a broader age range (3-12 year olds) [Kontogianni et al., 2010] and is greater than that found for pre-schoolers in Germany, the Netherlands and the U.S.A. [van Buuren, 2004; Kurth and Schaffrath Rosario, 2007; Hong et al., 2008].
In the present study overweight children were found to have significantly higher dmfs values compared with normal and underweight children. These results are in broad agreement with a Mexican study of 1,160 4-5 year old children [Vazquez-Nava et al., 2010] and in part (in the 60-72 month age group) with a U.S.A. study of 1,507 children aged 2-6 years old [Hong et al., 2008]. Four other studies found no significant associations between abnormal BMI values and dental caries: one in China [Chen et al., 1998] with 5,133 children aged 3 years, one in Brazil [Granville-Garcia et al., 2008] with 2,651 children aged 1-5 years and two U.S.A. studies with 4,167 and 1,719 children, both aged 2-5 years [Macek and Mitola, 2006; Kopycka-Kedzierawski et al., 2008]. All those studies used similar caries diagnostic criteria.
Role of paediatric dentists regarding obesity. The association between dental caries and BMI implicates some contributing factors, the key one of these being diet. Few children nowadays are monitored by a nutritionist and the paediatric dentist is in a position to inform parents about the benefits of following a healthy diet and to discuss obesity related issues. Moreover, calculating and monitoring each child's BMI is a simple and quick procedure, which should not be ignored. Depending on BMI results, when abnormal values are seen, a referral to a paediatrician should be considered [Vann et al., 2005].
BMI calculation problems. In some studies, BMI data are compared with international cut-off points using IOTF (International Obesity Task Force) standards, presented by Cole et al. [2000; 2007] and divided into four categories: underweight, normal in weight, overweight, and obese. In the USA different percentiles as cut-offs are used, based on 2000 CDC (Center for Disease Control and Prevention) growth charts (85th, 95th or 97th percentile) [Kuczmarski et al., 2002] with somewhat different categories: underweight, normal in weight, at risk for overweight and overweight. In some countries, BMI is calculated in relation to national data. In Greece, BMI data exist only for children living in urban Athens. This means that the usage of different cut-off points and references for a population leads to different results and makes comparisons between some studies difficult.
Limitations of the study. Potential confounders such as age or gender were not included in the analysis due to the unbalanced sample size of at least two of the BMI categories. In addition no dietary data were available.
Overweight Greek pre-school children are at risk of dental caries indicated by statistically significantly higher dmfs values than normal weight and underweight children.
Parental consent was obtained and the study was approved by the Ethical Committee of the Faculty of Dentistry, Aristotle University of Thessaloniki, Greece. The co-operation of Prof A. Deligiannis, Head of Thessaloniki municipality for cultural affairs and the day centre carers is warmly appreciated. Our gratitude is also due to the Plac Control Company for providing the disposable dental mirrors.
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A. Trikaliotis *, V. Boka *, N. Kotsanos *, V. Karagiannis **, M. Hassapidou ***
* Depts. of Paediatric Dentistry and ** Basic Dental Sciences, Aristotle University of Thessaloniki, *** Dept. of Nutrition and Dietetics, TEI Thessaloniki, Greece.
Postal address: Dr A. Trikaliotis. Dept. of Paediatric Dentistry, Faculty of Dentistry, Aristotle University of Thessaloniki, Greece. P.C. 54124.
Table 1. Distribution of dmfs percentiles per BMI category gender in a group of Greek children aged between 3 and 5.5 years old (n=361). dmfs Percentiles BMI 5 10 25 50 75 90 95 Underweight .00 .00 .00 .00 .75 5.00 8.00 Normal weight .00 .00 .00 .00 .00 2.00 4.90 Overweight .00 .00 .00 .00 1.25 8.20 15.55 Obese .00 .00 .00 .00 .00 7.20
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