INTRODUCTION
Early childhood caries (ECC) is a relevant public health problem 1. It has been defined as the presence of one or more decayed, missing (due to caries) or filled teeth in children 71 months of age or younger 2. With the addition of an unfavorable systemic condition such as child malnutrition, ECC acquires further meaning in terms of risk factors and complications.
Child malnutrition, according to the United Nations Children's Fund (UNICEF), is "the outcome of insufficient food intake (in quantity and quality), the lack of adequate care and infectious diseases". Deficient nutritional status impacts stature (chronic malnutrition) and weight (acute malnutrition), causing delayed growth and affecting the child's physical and mental development 3.
Child malnutrition contributes new forms of severity to ECC. Family and community socioeconomic variables have been included as potentiators of the severity and course of early childhood caries1,4-6, and it has been suggested that socioeconomically disadvantaged children are more vulnerable. In situations of poverty, the variable "malnutrition" is often added to the complex etiological panorama of ECC, thus affecting a disadvantaged social group that has barriers to access to both preventive and curative healthcare7,8. Malnutrition causes alterations in tooth development, leading to defects in enamel development and saliva composition through alteration of protein synthesis or mineral availability 9-11. This is why, in 2012, a new category was proposed for ECC associated to hypoplasia caused by nutritional deficiencies in early childhood stages 12. The comorbidity of ECC and childhood malnutrition has been studied, defining nutritional status by means of several anthropometric measurements and caries prevalence with the dmft index. Different studies have reported varying results:
A study in India in 2014 related body mass index (BMI) to dmft, and although it found no significant association between them, the group of children with low weight had the highest caries prevalence 13. Another study in Brazil in 2014 used WHO 2006 growth standards and found a statistically significant association between ECC and severe and mild malnutrition, though not between ECC and moderate malnutrition 14. In Cartagena, Colombia in 2009, children with chronic childhood malnutrition were found to have 82% caries prevalence and increased fluorosis 15. In Argentina, there are few studies on populations of malnourished children. One study relating saliva flow to nutritional status in overweight children analyzed a sample of 60 preschoolers in areas adjacent to Buenos Aires city, reporting that 5% of children were underweight according to BMI 16. In Barranqueras, Chaco, in 2007, 59 children were studied, finding differences between malnourished and normally nourished children regarding caries indices, delayed eruption chronology and increase in frequency of hypoplasia 17.
Many studies do not include the diagnosis of enamel lesions in the "decayed" component of indicators. As systematic review of caries in relation to body mass index reports this problem and, in order to avoid discrepancies in caries diagnostic criteria, recommends the inclusion of more sensitive systems such as ICDAS II (International Caries Detection and Assessment System) 18 and more studies in children under 6 years old 19. There are data on caries prevalence in low socioeconomic level preschoolers for Greater Mendoza, reporting 50.2% caries prevalence (including enamel lesions) for children under 6 years old 20. To date, no study has related ECC to child malnutrition in Mendoza Province. Accordingly, the aim of this study is to describe the frequency and severity of ECC and possible associations among variables in children with chronic and acute child malnutrition, aged 12 to 71 months in Greater Mendoza, Argentina, including both dentin and enamel lesions.
MATERIALS AND METHOD
A descriptive, cross-sectional, correlational study was performed using an intentional sample of 145 children diagnosed with chronic or acute child malnutrition, aged 12 to 71 months, who attended the Las Heras Center for Human Promotion and Prevention of Child Malnutrition, ( Centro de Prevención de Desnutrición Infantil y Promoción Humana de Las Heras) and the Teresa de Calcuta Hospital of the Cooperative Foundation for Child Malnutrition ( Fundación Cooperadora de la Desnutrición Infantil [CONIN]) in Mendoza during 2017 and 2018. Nutritional status diagnosis was obtained as secondary data contained in institutional Clinical Histories, determined as z-score for weight-for-height, weight-for-age, height-for-age, BMI-for-age and head circumference-for-age, and processed in the ANTRHO system (WHO) 21.
The study included all children whose parents or legal guardians provided written consent to participate in the project and excluded from the sample any children with reported comorbidity with diagnosed systemic diseases or whose behavior made it impossible to perform the practices. For ethical reasons, all children in the sample were included in an oral healthcare program. This project was approved by the Ethics and Research Committee of the University Hospital at Cuyo National University, under the Minutes of said Committee dated March 3, 2017. The following variables were considered: Age categories in months: 12 to 23 months; 24 to 35 months; 36 to 47 months; 48 to 71 months.
Dental status: recorded according to dmft and dmfs indices 22, but including within the category "decayed" ("d") non-cavitated enamel lesions (visible without drying) and cavitated enamel lesions, according to ICDAS II 2 to 6 active categories 18. Two levels of analysis were used: 1) including only dentin lesions: dmft 4-6 and dmfs 4-6, and 2) considering enamel and dentin lesions: dmft 2-6 and dmfs 2-6.
Severity of caries experience was recorded by dividing it into four categories for the dmft index, as follows: dmft=0; dmft: 1, 2, 3; dmft: 4, 5, 6; dmft: 7 or more, both for "d" 2-6 and "d" 4-6.
Clinical examination was conducted by two calibrated researchers (Kappa= 81%) using the visual method applying the ICDAS II criterion for diagnosis and activity. Data were analyzed statistically using SPSS software version 17.0. Central tendency and frequency distribution measures were applied. Non-parametric tests were used with significance level p=0.05: Wilcoxon rank test to compare dmft 2-6 to dmft 4-6 and dmfs 2-6 to dmfs 4-6, and categories of severity of caries experience dmft 2-6 and dmft 4-6; Kruskal-Wallis test and Spearman correlation coefficient to establish associations and correlation between results of dmft 2-6 and age; and chi-square test and Spearman correlation coefficient to study severity of caries experience according to age categories.
RESULTS
Distribution according to age groups was even (x2=2.44; p=0.485). The Kolmogorov-Smirnov test showed that the variables dmft and dmfs did not follow normal distribution, therefore non-parametric tests were applied to contrast the variables (dmft 2-6: Z KS=3.17, p=.000; and dmfs 2-6: Z KS= 3.73, p=.000)
Dental status indicators
Caries prevalence found for malnourished children was 48.2% when enamel and dentin lesions were considered. This prevalence declined to 35.2% when only dentin lesions were considered (dmft 4-6).
Mean dmft 2-6 was 2.10 ± 3.31 with very high disease burden denoted by a "d" component of 2.03 ± 3.24. The indicator behaved similarly when analyzed per surface, with dmfs 3.07±6.1 and "ds" 2.91±6.1. For dmft 4-6, values were 1.21 ± 2.46 with a "d" component of 1.14±2.37. For dmfs 4-6, values were 1.98 ± 5.14 and its "d" component was 1.86±5.06 (Table 1).
Wilcoxon rank test was used to compare dmft 2-6 to dmft 4-6 and dmfs 2-6 to dmfs 4-6, finding a significant difference between both pairs of variables, which shows that indicators that include enamel lesions are significantly higher than those that only consider dentin lesions (dmft: Z=-6.69; p= .000; dmfs: Z=-6.67; p= .000).
Types of caries lesions according to ICDAS II active categories
Active enamel lesions observed in this study (ICDAS II active categories 2 and 3) accounted for 37% of total lesions. Active lesions type 5 were the most frequent (32.1%) ( Fig. 1). In the first age category, 80% corresponded to enamel lesions.
Severity of caries experience
For both levels of analysis, severity of caries experience showed the highest percentages for the categories dmft 2-6 and 4-6 =0 and dmft 2-6 and 4-6: 1, 2 and 3.
Significant differences were found between the categories for severity of caries experience dmft 2-6 and dmft 4-6, increasing the values = 0 when only dentin lesions were considered, and increasing the values 4, 5, 6 and 7 or + when enamel lesions were included in the indicator (Wilcoxon rank test Z= -6.04; p=.00) (Table 2).
Dental status according to age categories
Dental status indicator was taken as dmft 2-6 in order to include in the analyses all categories of caries lesions. Values for dmft were 0.11±0.39 from 12 to 23 months; 1.38±2.36 from 24 to 35 months; 2.41±2.44 from 36 to 47 months and 4.53±4.62 from 48 to 71 months (Table 3).
The Kruskal-Wallis test (KW=45.79; p=0.00) confirmed that there are significant differences between the results of dmft 2-6 and children's age in the study.
The Spearman correlation coefficient between dmft 2-6 and age categories in months was positive but moderate (Spearman's Rho = 0.561; p= 0.00), corroborating the tendencies described previously.
Severity of caries experience according to age categories
A statistically significant association was found between the categories of dmft 2-6 and age of malnourished children in the study (x 2=54.578; p=0.00), with a positive though moderate correlation between severity of caries experience and age (Spearman's Rho =0.559; p=0.00). The contingency table for the two variables shows that at higher ages, there is an increase in cases of the categories with caries, and reduction in cases without caries (Table 4).
DISCUSSION
This study brings to light the problem of ECC in children under six years old diagnosed with child malnutrition in Mendoza, Argentina.
Caries prevalence was 48.2% when examination included early enamel lesions and 38.2% when only dentin lesions were considered. Other studies in different parts of the world report different prevalence values. Tsang et al. (2019) report caries prevalence of 58.2% and a mean value of 3 for the "decayed" component of dmft in populations of malnourished children under 6 years old in Nepal 23. Janikaram et al. (2019) report caries prevalence of 33.2% in similar populations 24.
It should be highlighted that the values found in the current study are similar to those reported in a previous study on caries prevalence in children under six years old in Mendoza Province. Said study on children with low socioeconomic level in Greater Mendoza reported caries prevalence of 50.2 for enamel and dentin lesions and 35.2 for dentin lesions 20. Malnourished children constitute part of the population with low resources, so it is expectable that they would share risk factors with the previously studied population in Mendoza. The similar prevalence values found in the mentioned study can be considered as a reference framework to understand the severity of the problem in this particular epidemiological scenario.
Discrimination of the dmft index shows that there was a main burden of the decayed component, with very little intervention or treatment, in agreement with other studies24,25. This reflects the low demand for dental treatment, and it may be assumed that there are barriers to access to healthcare in common with other child populations, regarding ECC 7. Values for dmft and dmfs tended to increase with age, being four times higher in the 48- to 71-month age group than in the 24- to 35-month age group. One study in Nigeria found a similar relation in children with and without malnutrition 26. In the current study, the difference between dmft 2-6 and dmft 4-6 was statistically significant. It is interesting to note that 31% of the affected surfaces were enamel lesions, and that in the first year of life, 80% of the lesions were enamel lesions. Although the caries indicators are not high (as expected for the age), caries onset occurred early in life for the malnourished children in the study.
The severity of caries experience, measured through 4 dmft score categories, for both dmft 2-6 and dmft 4-6, showed that the most frequent categories were dmft=0 and dmft= 1, 2, 3. However, evaluation of differences between dmft 2-6 and dmft 4-6 showed that when enamel lesions were considered, there was a significant increase in the categories dmft= 4, 5, 6 and dmft= 7 or more. One of the aforementioned studies in Nepal also described severity categories according to mean dmft, but considering that among children who only experienced caries, 50% presented 1 to 4 decayed teeth, 35.3% had 5 to 9 decayed teeth, and 14.6% had 10 or more decayed teeth 23.
It was also found that severity of caries experience increased with age, with a positive though moderate correlation between severity of caries experience and children's age.
These results emphasize the importance of early prevention, detection and treatment of ECC in malnourished children. Timely action is needed to prevent both, pathological and quality of life