Factors associated with early childhood caries among 3 to 6 year old children in India: A case control study

1 Introduction

Early childhood caries (ECC)] is basically the caries in primary dentition. ECC has been defined as the presence of one or more decayed teeth (with non-cavitated or cavitated lesions), missing teeth (due to caries) or a filled surface on any primary tooth in a child aged 71 months old or younger [1]. ECC is a major public health problem worldwide [2]. Untreated caries in deciduous teeth was the 10th most prevalent conditions, affecting 9% of the global population [3]. ECC has been associated with several etiological factors [4], however in recent times the focus has been shifted from biological risk factors to behavioral and social risk factors in etiology of ECC [5].

ECC has been more prevalent in developing countries [6, 7] and socio-economically disadvantaged population [8]. With the improvement in the living conditions because of industrialization and urbanization resulted in unwanted changes in lifestyle. These have eventually led to significant increase in prevalence of obesity [9, 10]. Conversely, prevalence of under-weight children in India is among the highest in the world [11]. Role of BMI (BMI is a person’s weight in kilograms (kg) divided by his or her height in meters squared) in etiology of ECC has been studied [12, 13]. A recent systematic review found a significant association between obesity and dental caries, but on subgroup analysis based on type of dentition there was no association between obesity and caries in primary dentition [14]. Many of the peri-natal factors like gestational age, birth weight and mode of delivery are also found to influence the prevalence of ECC [15]. Despite being largely preventable ECC remains one of the most common childhood diseases [16]. ECC considered as “an indicator of preventive missed opportunities”. For prevention, understanding the risk factors of ECC is essential. On literature search we observed not much research is done to assess the association of these risk factors with ECC among Indian children. Therefore, this study aim to assess the association between ECC and risk factors, such as SES (Socioeconomic status is the social standing or class of an individual or group. It is measured as a combination of education, income and occupation), BMI, Gestation age, birth weight and mode of delivery among Indian children aged 3 to 6 years.

2 Methodology

This cross-sectional study assesses the association between ECC and risk factors including age, gender, BMI, birth weight, type of delivery, gestational age and SES among 3 to 6 year aged school children in Sangli city, Maharashtra. Ethical approval to conduct this study has been obtained by research ethics review committee and is conducted in accordance with the Declaration of Helsinki.

All the children aged 3–6 years whose parents/guardians gave consent to participate in the study and who co-operated during the oral examination were included in the study. Children with physical or intellectual disability were excluded as it may influence oral hygiene practices, dietary practices and physical activity. The children with any syndromes that can impact oral cavity were also excluded.

A 54% prevalence rate for ECC [17], 5% type I error and 80% power of the study were considered in calculating the sample size, establishing a minimum sample of 340 children per group. Five government and five private primary schools from Sangli city were randomly selected from the list of schools obtained from DDPI (Deputy Director of Public Instruction, Education department of Sangli). Prior permission to conduct the study was obtained from the authorities of respective schools. From each school about 30 participant with ECC and 30 without ECC were randomly selected after identifying the cases and controls through oral health screening. Informed consent forms were given to the class teachers which were to be sent to the parents of the children explaining the study details (Local language).

Data acquisition involved an oral clinical exam, anthropometric measures and a questionnaire administered in interview form to acquire information on socio-demographic data and Gestational age [According to WHO, Preterm – less than 37 weeks or full-term- 37 or more weeks] [18]; mode of delivery (Normal or cesarean); birth weight and socio-economic status (SES).

All the oral examinations were performed by single examiner. The examiner underwent a calibration and training exercise for the diagnosis of early childhood caries. Calibration was performed on 15 children with ECC diagnosed by a pedodontist in pedodontic department of institution. Examinations were done on two separate occasions with a one-week interval between sessions. Kappa coefficient for intra-examiner agreement was 0.86 and inter-examiner agreement was 0.81. Oral examinations were performed at school setting. The child remained seated in a chair in front of the examiner and facing a window, to make use of natural light. The visual examination criteria of the World Health Organization (WHO) were used for the diagnosis of dental caries. ECC was dichotomized as absent or present. For anthropometric measurement [BMI], the children were weighed on a weighing machine. The instrument was calibrated using an object of known weight. Height was determined using measuring tape with a millimeter scale. The researchers who measured the BMI underwent a training process prior to the data collection. Kuppuswamy scale with updated version was used to assess the SES of parents [19].

Data analysis performed using SPSS software version 17. Descriptive statistics employed to study characteristic of participants. To test the association between two categorical variables, the chi-squared test was used. The strength of association between risk factors and ECC was assessed using multiple logistic regression analysis. Goodness of fit of the regression model was assessed with omnibus test and Hosmer–Lemeshow χ2 statistics. The margin of error for statistical significance was 5%.

3 Results

Under this study, a total of 690 participants participated, of which 345 diagnosed with ECC of various severity (Table 1). Results of chi-square test revealed all the independent variables significantly associated with outcome except gender, mode of delivery and birth weight. In Table 3, Omnibus test (P value: 0.001) and Hosmer and Lemeshow (P value: 0.284) test shows multivariate regression model is a good fit for data. Nagelkerke coefficient (R²) suggests that the model explains only 10.6% of the variation in the outcome. In Table 4, Multivariate logistic regression analysis shows increase in age as a significant risk factor for ECC. Male participants are 28% (OR: 1.28) more prone to ECC than females. Children with preterm birth had more chances (OR: 1.65) of having ECC than full-term birth. Cesarean section is associated with increased risk of ECC however this association is not statistically significant. BMI is a significant predictor of ECC but its association with ECC is not uniform. SES gradient is inversely associated ECC and this association is significant. Participants under Lower middle SES are at three times more risk of developing ECC than upper SES category.

Early childhood caries is a major health concern worldwide [16]. Studies have proven that ECC has significant impact on the child’s quality of life, which hampers regular activities like eating, sleeping and playing [20]. It is a multifactorial disease in which various risk factors interact. This study examined a set of risk factors including BMI, birth weight, age, gender, gestation period and mode of delivery. Present study validates significant association with all the above variables except gender, birth weight and mode of delivery. Likelihood of ECC increased with age which was consistent with previously reported data [21, 22]. With increasing age there can be accumulation of risk factors and there by increases the risk of ECC. This study results indicate a strong association of ECC with SES. Adjusted analysis demonstrates increased risk of ECC with decrease in SES (Table 4). Consistently this finding is been proven in several previous researches [16, 24].

Childhood obesity has become global health problem [14] and it is considered one of the common risk factor for several oral diseases [25]. We have found a significant association between BMI and ECC but this association is not uniform throughout the levels of BMI (Table 4). This might have happened because of uneven distribution of participants under each BMI categories (Table 2). The association between obesity and ECC is still debatable as studies shows conflicting results [14, 20]. This highlights the need of more quality longitudinal research to confirm this association. A systematic review highlights the need of controlling the confounders like age while assessing the association between obesity and dental caries [14]. Multivariate analysis showed participants with preterm birth are more prone (OR: 1.65) to ECC than full-term birth. Preterm birth is associated disturbances in growth and development of primary and permanent dentition [26]. They may have difficulties in performing daily oral care because of disturbed motor function, cognitive and behavioral impairments [26, 27]. They also experience disturbed enamel mineralization, immune system which may predispose for caries [28, 29].

Mode of delivery failed to show significant association with ECC in this study. Previous research found that the colonization of Mutans Streptococci in young children was affected by the mode of delivery [30, 31]. Vaginally delivered newborns go through the birth canal there by acquire a variety of maternal indigenous bacteria that are different from newborns delivered by C-section [32, 33]. But information on the effect of delivery mode on caries outcome is scant [30]. This study also revealed non-significant association between birth weight and ECC. In contrary, studies have shown low birth weight as a potent risk factor in causation of ECC [34–36]. Low birth weight is found to cause enamel hypoplasia by that it increases the probability of caries.

In summary, the present study demonstrated that ECC is associated with age, SES, BMI and gestational age. However, this association cannot be considered as causation as the present study is cross-sectional study. This design cannot demonstrate temporal relationship of causation. Major limitation of our study is we didn’t consider few covariates in study like oral hygiene, dietary practices and oral health behavior which may influence the results. Further studies need to approach this concept with wider dimension considering all the covariates and with more valid cohort study design.

5 Conclusions

Consistently researches have proved the association of ECC with early life biological and social factors. This signifies the need for early life interventions and precautions with consideration to potential risk factors of ECC. Promoting positively the maternal attitude toward good oral health, and promote healthy behaviors and practices, is essential to reduce the ECC.