Dental Caries Experience in 6-13 Years Old School Children of Dharan Sub-Metropolitan City, Nepal: A Cross-Sectional Study

Introduction: Dental caries though preventable oral health problem is affecting school children worldwide and around 50% of Nepalese children are suffering from it. Baseline data with good understanding of dental caries and associated risk factors are necessary to form preventive strategies for setting and achieving oral health goals. Objective: This study was conducted to determine dental caries experience and associated risk factors among school-going children of 6-13 years old in Dharan sub-metropolitan city, Nepal. Methods: A cross-sectional study was conducted from 5 th Jan 2018 to 4th Jan 2019 among 680 school children selected by multistage cluster sampling method. Pretested, standardized, closed-ended questionnaire answered by the parents was used to gather information regarding the associated risk factors. Dental caries experience was obtained from deft/DMFT (WHO modification 1997). Comparison of categorical data was done using Chi-square test. Multivariable binary logistic regressions were used for the statistical analysis. Results: The overall caries prevalence was 61.6%, in primary dentition it was 48.25% and in permanent dentition it was 34.4%. Dental caries experience was with mean deft 4.67 ( ± 2.7) in primary dentition and mean DMFT 1.72 ( ± 1.05).in permanent dentition. Multivariate analysis showed significant association between dental caries experience and grade three and grade four school children had experienced greater caries (p<0.05, OR =2.7). Dental caries was associated with eating sweets at night (p<0.001, OR=2.5) and snacking in-between meals (p<0.001, OR=2.5). Conclusions: Dental caries among school-children in Dharan showed a significant burden especially within the primary dentition. It was significantly associated with factors like feeding habits -eating sweets in a day, eating sweets at night and snaking in between meals.


INTRODUCTION
Dental caries is one of the major global oral health problems as it affects majority of school children worldwide. 1It is Dental Caries Experience in 6-13 Years Old School Children of Dharan Sub-Metropolitan City, Nepal: A Cross-Sectional Study Bhawana Sigdel Bastola, 1 Bandana Koirala, 2 Mamta Dali, 3 Sneha Shrestha, 4 Dharanidhar Baral 5 an emerging public health problem amongst the child population in Nepal.A study done in eastern Nepal found dental caries to be 60.3% and 55.6% in the primary and permanent dentition, respectively. 2ntal caries is a multifactorial disease.7][8] Food habit is another factor having greater influence in dental caries. 9Caries risk is increased if the sugar is consumed between-meals and in a form which adheres to the teeth. 10Untreated dental caries with the prevalence of 58% in young Nepalese children is more than malnutrition that affects 53% of the child population. 11ildhood dental caries is a serious dental public health problem that warrants immediate attention of the government and dental profession officials.Hence, this study aimed to assess the dental caries experience and its associated risk factors in 6-13 years old school children in Dharan sub-metropolitan city.

METHODS
It was a descri ptive cross-sectional study conducted amongst 6-13 years old school children of Dharan submetropolitan city of eastern Nepal.Ethical clearance was obtained from the Institutional Review Committee (IRC) with reference number (226/074/075), BPKIHS, Dharan.Duration of the study was one year from 5th Jan 2018 to 4th Jan 2019.Dental caries experience was obtained from deft/DMFT (WHO modification 1997).Modification of Kuppuswamy's socioeconomic status scale in context to Nepal was used to access the socioeconomic status. 12mple size for this study had been calculated considering 56% prevalence of dental caries from the study done by Bhagat TK et al. 2 For prevalence studies, Where, n= sample size, Zα α αα= Z statistic for a level of confidence.

RESULTS
A total of 680 children studying in the private and public schools of Dharan were included in the study.Majority of the children belonged to private schools.Distribution  1.Similarly, oral hygiene habits, feeding habits, and dental visit of the children were assessed and the results are shown in Table 2.
The overall dental caries prevalence in the present study was found to be 61.6%, of which primary dentition was 48.25% and permanent dentition was found to be 34.4%.Whereas, dental caries experience was with mean deft±S.D 45±9.85 in primary dentition and dental caries experience in the permanent dentition was found to be with mean DMFT±S.D of 1.72±1.05and mean DMFS±S.D of 1.83±1.45.In case of decayed, missing or extracted and filled individual components in the primary and the permanent dentitions, decayed portion was seen to be the highest, primary (42.1%) and permanent (32.8%).Missing/extracted component in the primary dentition and permanent dentition were found to be 16.8% and 0.3% respectively, whereas, filled component in the primary dentition and permanent dentition were found to be 7.1% and 1.9% respectively.
The tooth-wise distribution of dental caries experience in case of permanent teeth showed first permanent molars to be the most commonly decayed teeth with 22.9% in mandibular right first molars and 18.1% in mandibular left first molars followed by maxillary right and left first molars ).However, mandibular anterior teeth were the least affected i.e., just 0.1%.Surface-wise distribution on both the primary and permanent teeth showed occlusal surface to be the most commonly decayed one.
Association of sociodemographic characteristics viz.oral hygiene habits, feeding habits and dental visit with dental caries experience is shown in Table 3.The variables which were associated with dental caries experience and variables with less than p<0.20 from bivariate analysis were included into multivariate binomial logistic regression analysis after controlling for confounder such as tooth brushing.Nocaries was taken as a reference category and compared with the caries experience group and inferred with the help of adjusted odds and 95% confidence interval to interpret the findings.The final binomial logistic regression analysis on the dental caries experience is shown in Table 4.

DISCUSSION
The present study was done in the schools, as it is considered as a miniature model of larger community and one of the best places for oral health promotion where all children, irrespective of their gender, socioeconomic status, and ethnicity can be reached.In the present study, dental caries was found to be significantly associated with feeding habits like eating sweets in a day and at night, snacking in between meals and time of dental visit.It was also found that more than half of the children (61.6%) experienced dental caries, of which 48.25% involved primary teeth with the mean deft of 4.67 (±2.7) and 34.40% permanent teeth with the mean DMFT of 1.72 (±1.05).
Prevalence of dental caries in primary dentition was lower in the present study as compared to the studies conducted by Dixit LP et al. 13 (52%) and Thapa P et al. 14 (64.4%).
Male partici pants experienced more caries (62.5%) compared to the female partici pants (60.8%) in the present study, but this association was not statistically significant (p=0.657).In Nepal, majority of the upper and uppermiddle socioeconomic class have been shown to afford to send their children to private schools. 16,17 resent study showed children from private schools (63.8%) experienced higher dental caries compared to their public (56.5%)counterparts.Similar finding was reported by Basha et al. 4 However, this association was also not seen to be statistically significant (p=0.077).
In the present study, among 680 children, 675 brushed their teeth, whereas findings of Dixit LP et al. reported very poor brushing habit of 56%.13Only 414 (61.3%) out of 675 experienced caries while remaining five who did not brush their teeth had 100% caries experience and this finding was statistically significant (p=0.162).Similarly, 203 (63.8%) children who brushed their teeth once or less every day showed more caries experience than those who brushed their teeth more than once daily.Again, children who used non-fluoridated toothpaste (67.5%) had higher caries experience than 59.3% of children who used fluoridated toothpaste.This proves the importance of efficacy of regular tooth brushing with fluoridated toothpaste in minimizing the caries occurrence, especially in children of our part of Nepal where fluoride level was below the optimal value of Nepal (0.5 mg/l). 18nerally in Nepal, parents wait for their child to reach three to four years of age to introduce tooth brushing to them which is contrary to the need for start of early caries preventive efforts. 19It was thus found, only few i.e., 136 (20.1%) to have brushed below two years and most of the children 539 (79.3%) to have brushed their teeth only after they reached more than two years of age.Among them, 61.6% of the children experienced caries compared to the 60.3% who brushed at age less than two years.
Rinsing of the mouth with water after meal is also a common practice in Nepal. 16Similar practice was observed in the present population with maximum children (84.1%) having the habit of mouth-rinsing.Children who did not rinse their mouth experienced more caries, i.e., 1.78 times than those who practiced mouth-rinsing habit, and this association was found to be significant (p=0.022).
Frequency of consuming sweets was directly related to the caries experience in the present study.Similarly, 113 children (79.0%) who used to consume sweets at night had greater caries experience i.e., 2.5 times more than those who did not consume sweets at night 306 (57.0%).Present findings were also supported by the study of Lueangpiansamut J et al with significant association (p=<0.001) of sweets consumption before bedtime to increase dental caries. 19jority of the children i.e., 537 (79%) also had the habit of snacking in-between meals.Among them, we observed 357 (66.5%) children to have higher caries experience (2.1 times greater) than those who did not have this snacking habit i.e., in 62 (43.4%).0][21] It was also found that more than half, i.e., 58.8% of the children never visited the dentist, whereas, 41.8% of them had visited at least once and among them also 71.1% of children experienced caries.Findings of Khanal S et al. 22 showed the dental visit to be very poor (only 5.6%) and among them 77.4% visited only when they had pain.In the present study, only clinical examination was done and no radiographs were taken, which might have underestimated the actual magnitude of the problem and also, true results might have been obscured due to the incorrect reporting (recall bias) to questions that were answered by the parents regarding children's oral hygiene and feeding habits.Thus, this study has elucidated that dental caries is still a major affliction in our children population and urgent start for implementation of awareness programs for promoting early preventive measures hold utmost importance for uplifting the oral health status of the children of Dharan sub-metropolitan city.

Table 2 . Distribution of children according to oral hygiene habits, feeding habits and dental visit (n=680).
Bastola et al.Dental Caries Experience in 6-13 Years Old School Children of Dharan Sub-Metropolitan City, Nepal: A Cross-Sectional Study of children according to different sociodemographic variables is given in Table