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Table of Contents   
ORIGINAL ARTICLE  
Year : 2013  |  Volume : 6  |  Issue : 4  |  Page : 422-429
Prevalence of dental caries and dental fluorosis among 12 and15 year-old school children in an endemic fluoride area of Nalgonda district, Andhra Pradesh, India


1 Department of Public Health Dentistry, Government Dental College and Hospital, Hyderabad, India
2 Department of Public Health Dentistry, Sri Sai College of Dental Surgery, Vikarabad, India
3 People's Dental Academy, Bhanpur, Bhopal, Madhya Pradesh, India

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Date of Web Publication26-Feb-2014
 

   Abstract 

Introduction: The published literature on the prevalence of dental caries and fluorosis in Nalgonda district, an endemic fluoride belt in India was scanty. Objective: To determine the prevalence of dental caries and dental fluorosis among 12 and 15 years old school children in relation to fluoride concentration in Nalgonda district. Materials and Methods: Stratified random sampling technique was employed to select 20 schools from Nalgonda district. These areas were divided into four categories, low, medium, high and very high fluoride areas based on the fluoride concentration. The oral examination for dental caries and fluorosis among children who fulfilled the inclusion and exclusion criteria were conducted by a single trained and calibrated examiner using mouth mirror and CPI (Community Periodontal Index) probe under natural daylight. The data analysis was done using Statistical Package for Social Sciences SPSS version 16. Results: The prevalence of dental caries among 12 and 15 year old school children was 42.6% and 48.6% respectively. The prevalence was more among females (56.9%) than males (34.2%). The prevalence was more in low fluoride area (67%) followed by very high fluoride area (56.1%). The lowest prevalence was in medium fluoride area (20.5%). The prevalence of dental fluorosis increased with increasing fluoride concentration with no difference in the gender and age distribution. Conclusion: Defluoridation of water in areas where the concentration of fluoride is more than optimal is an immediate need as dental fluorosis is a major public health problem in these areas.

Keywords: Children, defluoridation, dental caries, dental fluorosis, endemic fluoride area, prevalence

How to cite this article:
Sukhabogi JR, Parthasarathi P, Anjum S, Chandra Shekar B R. Prevalence of dental caries and dental fluorosis among 12 and15 year-old school children in an endemic fluoride area of Nalgonda district, Andhra Pradesh, India. Ann Trop Med Public Health 2013;6:422-9

How to cite this URL:
Sukhabogi JR, Parthasarathi P, Anjum S, Chandra Shekar B R. Prevalence of dental caries and dental fluorosis among 12 and15 year-old school children in an endemic fluoride area of Nalgonda district, Andhra Pradesh, India. Ann Trop Med Public Health [serial online] 2013 [cited 2020 Sep 23];6:422-9. Available from: http://www.atmph.org/text.asp?2013/6/4/422/127785

   Introduction Top


Dental caries though is in the declining trends in many parts of the industrialized world, it is still a major public health problem in most of the developing countries, affecting 60-90% of the school children say a World Health Organization (WHO) report. In the developing world, economic, social and political changes have had a significant impact on diet and nutrition, with a shift from traditional to a more westernized life style. On the contrary, it is observed that resources are inadequate for any primary preventive measures. Besides, lack of public health awareness and motivation seems to be major contributors for increase in dental caries. [1] India is one among the 25 nations around the globe, showing increasing trends in dental caries. Here, dental caries exists as a smoldering disease that has ingressed its tentacles deep in to those regions where there are inadequate resources of dental treatment, lack of public health awareness, motivation and increase in the utilization of refined carbohydrates. [2] The school children in India have the dual problems of dental caries and dental fluorosis. The endemic fluorosis areas in India cover around 15 states. Many laboratories, clinical and dental public health researchers have concluded after more than 70 years of research that, fluoride is a double-edged sword. Its deficiency leads to Dental Caries and excess consumption in the first 5-10 years of life leads to Dental fluorosis. [3] The effect of fluoride on the dentition is dose-dependent and is not confined to increased caries resistance. If accumulated above certain levels in the body, fluoride causes various disorders, together called as fluorosis. A recent WHO report says, "It may not be possible to achieve effective fluoride based caries prevention without some degree of dental fluorosis". Public health administrators must seek to maximize caries reduction, while minimizing dental fluorosis. [4] According to some reports, [5],[6],[7]] the caries prevalence tends to reduce with increasing fluoride levels in the drinking water, thus indicating a negative association between fluoride and dental caries. However, some studies have indicated no relation [8] or a positive relation [9],[10] between the fluoride concentration in the drinking water and dental caries. Nalgonda District is an endemic fluoride belt where the fluoride concentration ranges from as low as 0.1 ppm to as high as 12 ppm. There are 1155 revenue villages with 3359 habitations out of which, 1122 habitations were identified as fluoride affected. [11] The literature on the prevalence of dental caries and dental fluorosis among the school going children in Nalgonda district is scanty. The present study was an attempt to determine the prevalence of dental caries and dental fluorosis among 12 and 15 years old school children in relation to fluoride concentration in Nalgonda district.


   Materials and Methods Top


This cross sectional study was conducted among 12 and 15 year old school children of Nalgonda district, Andhra Pradesh, India over a period of 10 m from October 2008 to July 2009. A pilot study was conducted before the commencement of the study on a convenient sample (n=100) in study area to determine the sample size, to assess the applicability, feasibility and accuracy of the questionnaire, the examination procedure and also to verify the appropriateness of the inclusion and exclusion criteria. After the pilot study, prevalence of dental caries was found to be 30%. Depending on the results of the pilot study, the sample size was determined to be 2000 after accounting for the design effect. A stratified random sampling technique was used for selecting the children into the study. The entire geographical area of Nalgonda district was divided into four strata. The list of all the mandals (administrative division) in these strata was collected. Five mandals from each of these strata were selected using the table of random numbers [Figure 1]. The list of all the secondary schools in each of these selected mandals was collected from the office of district education officer, Nalgonda. One secondary school from each of these twenty mandals (in four strata) was selected using the table of random numbers. The district of Nalgonda had total of 2112 secondary schools. Five schools from five different mandals (in four strata) was approximately 1% of the total number of schools in the district. The information on the total number of children in grade VI and IX in these twenty selected schools was obtained from the concerned head masters. The secondary schools having less than 50 children in each of these grades were not considered but were replaced by other schools in the same mandal selected randomly. In the selected schools, the first 50 children (25 males and 25 females) who fulfilled the inclusion and exclusion criteria in VI and IX grades were considered for the final analysis. The number of children varied in different schools. One of the schools from strata three had only 23 eligible male children in grade VI and hence 27 female children (instead of 25) were considered from grade VI in this school.
Figure 1: Map of Nalgonda district with 59 mandals

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Inclusion criteria

  1. School children, aged 12 and 15 years who were lifelong residents of that particular region and who were using the same source of drinking water from birth to at least 10 years of their life.
  2. Children with all permanent teeth, except third molars, with at least more than 50% of the crown erupted.


Exclusion criteria

  1. Children who had migrated from some other place or who were not the permanent residents of that particular area.
  2. Children who obtained their drinking water from more than one source in the initial 10 years of their life.
  3. Children with orthodontic brackets were excluded as this hindered diagnosis of enamel defects.
  4. Children with severe extrinsic stains on their teeth in whom assessing fluorosis was not possible.


Ethical clearance was obtained from the Ethical Committee of Sri Sai College of Dental Surgery, Vikarabad, before commencement of the study. Prior permission was obtained from the District Educational officer (DEO), Nalgonda. Informed consent was obtained from the school heads and verbal consent was obtained from parents on behalf of students, before the intra-oral examinations. A schedule for conducting the oral examination of these selected school children was prepared and circulated to all the concerned schools. The head masters of the schools were requested to issue a circular requesting the parents/guardian/elder brother or sister of Grade VI and IX students to be present in the schools on the day of scheduled oral examination of their ward. A pre-designed structured and pilot tested questionnaire was used to collect the information on dietary habits, method of cleaning, frequency of brushing, frequency of sugar consumption and source of drinking water. This questionnaire was filled by the examiner himself by a face to face interview with the parent/guardian/brother or sister. The data of the children without any family members in the school to give reliable information were not considered for the final analysis. The oral examination of children was carried out by a trained and calibrated examiner using a mouth mirror and CPI (Community Periodontal Index) probe. The training and calibration of the examiner was carried out in the department of Public health dentistry, Sri Sai College of Dental Surgery, Vikarabad, on a group of 20 children selected from one of the nearby schools to the institution after obtaining the institutional ethical clearance. The 20 children were examined by the investigator at two different times with an interval of six hours between the examinations. The Intra-examiner agreement was determined using the weighted kappa (k). The intra examiner agreement scores for Decayed Missing Filled teeth (DMFT) (k=0.93) and fluorosis (k=0.84) indices were substantial to almost perfect, according to the scale of Landis and Koch. [12] The clinical examination was carried out under adequate natural light in an isolated room. Participants were made to sit on a chair in an upright position using wall as the head rest, whenever necessary. Dental caries was assessed using Dentition status and treatment needs and dental fluorosis using Dental fluorosis index (WHO oral health surveys). [13] Dental caries was recorded at D3 level. The decayed teeth (D component), teeth missing because of dental caries (M component), teeth filled because of caries (F component) were counted separately and then totaled to get the DMFT value in each subject. All the teeth present in the oral cavity were visually examined and the two maximally affected teeth were selected for scoring the severity of dental fluorosis as per Dean's criteria. The dental fluorosis index score was computed for each subject. After the examination, a bottle was given to the first child of the school to collect the water from the source. The investigator/assistant accompanied the child at the time of collection of water sample. Another bottle was given to the next child, only if the source of drinking water was different from the previous one. Children were asked to collect the water from the source, which was used in the initial 10 years of their life. The water bottles were collected, coded and sent to laboratory for estimation of fluoride concentration. The serial number on the bottle indicates the serial number of the source of drinking water and this number was recorded in the questionnaires of all the children who consumed water from that particular source. Thus, drinking water samples of all the study participants were collected and the investigator was not having any information on the concentration of fluoride in the drinking water at the time of oral health examination of the children. The fluoride concentration in the drinking water was estimated using Orion 720A fluoride meter, coupled with ion specific electrode at "National Institute of Nutrition (Indian Council of Medical Research) (N I N) (ICMR) Hyderabad". Depending on the fluoride concentration, the areas were divided into four categories, low fluoride area (Fluoride concentration <0.7 ppm), medium (0.7 to 1.2 ppm), high (1.2 to 4 ppm) and very high fluoride area (4 to 6.28 ppm). The data was analyzed using SPSS version 16. The quantitative data was presented as mean and standard deviation, qualitative data as frequencies and percentages. The difference in the prevalence of dental caries and fluorosis between different categories was analyzed using chi-square test. The difference in mean DMFT scores between different categories was compared using Kruskal Wallis test as the data was not following normal distribution. Spearman's correlation coefficient was used for correlating mean DMFT score and DFI (dental fluorosis index) score with fluoride concentration in the drinking water. The statistical significance was fixed at 0.01. The autoclaved set of instruments was used for oral examination of the children.


   Results Top


Among 2000 study population, 1000 were from 12 years group and 1000 were from 15 years group [Table 1]. The study had 998 males and 1002 female children. The study area was divided into four categories based on the fluoride concentration. A total of 264 (26.5%) males and 258 (25.7%) females in the study were from low fluoride areas. The number of males and females in medium, high and very high fluoride areas was 36 (3.6%) and 42 (4.2%), 494 (49.5%) and 507 (50.6%), 204 (20.4%) and 195 (19.5%) respectively [Table 2].
Table 1: Age distribution of the study population in different fluoride areas

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Table 2: Sex distribution of the study population in different fluoride areas

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Dental caries prevalence

The prevalence of dental caries among the study population was 45.6%. The prevalence was highest in the low fluoride area (67%) followed by very high fluoride area (56.1%). The lowest prevalence was in medium fluoride area (20.5%). The difference in the distribution of caries in different fluoride areas was statistically significant (P = 0.000, [Table 3]). There was a statistically significant difference in the caries prevalence between medium fluoride area and others. The difference between medium and high fluoride area was less pronounced than the difference between medium and low, as well as medium and very high fluoride area. The same result was found even when a separate comparison was made between different fluoride areas in individual age groups (P = 0.000, [Table 3]).
Table 3: Prevalence of Dental caries among 12 and 15 years old school children in different fluoride areas

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The prevalence of dental caries was more among 15 years (48.6%) school children compared to 12 years (42.6%) and the difference was statistically significant (P = 0.008, [Table 3]). The prevalence of dental caries was more among female children (56.9%) compared to male children (34.2%) and the difference was statistically significant (P = 0.000, [Table 3]). The result was true even when a separate comparison was made between the genders among 12 and 15 year old children. In both the age groups, the prevalence was higher among females than male children (P = 0.000, [Table 3]).

Dental fluorosis prevalence

The overall prevalence of dental fluorosis was 77.6%. The prevalence in the low, medium, high and very high fluoride areas was 30.3%, 34.6%, 96.8% and 100% respectively. The prevalence was increasing with increasing fluoride concentration and the finding was statistically significant (P = 0.000, [Table 4]). The prevalence of dental fluorosis among 12 years old children was 77.5% and among 15 years old children, it was 77.8% with no significant difference (P = 0.87, [Table 4]). There was no statistically significant difference in the prevalence of dental fluorosis between male and female children (P = 0.44, [Table 4]).
Table 4: Prevalence of dental fluorosis among 12 and 15 years old school children in different fluoride areas

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   DMFT Score and DFI (Dental Fluorosis Index Score) In Different Fluoride Areas Top


The mean DMFT score (standard deviation in parentheses) for the study population was 0.75 (1.02). The score was highest in low fluoride area {1.22 (1.17)} followed by very high fluoride area {0.94 (1.04)}. The lowest score was noted in medium fluoride area {0.26 (0.57)}. The difference was statistically significant even when the comparison was made among different age and gender groups separately (P = 0.000, [Table 5]). The mean DMFT was significantly more among 15 year old children {0.82 (1.07)} than 12 year old children {0.67(0.95)} (P = 0.002, [Table 5]). The mean DMFT value was more among female children {1.06 (1.18)} than male children {0.43(0.69)} (P = 0.000, [Table 5]). There was a negative correlation between fluoride concentration (rho=−0.078, P = 0.000) in drinking water and mean DMFT score, a positive correlation (rho = 0.89, P = 0.000) between dental fluorosis index score and fluoride concentration [Table 5]. The study found no statistically significant difference in terms of dietary habits, method of cleaning, frequency of brushing and frequency of sugar consumption among the study population in different fluoride areas.
Table 5: Distribution of mean DMFT scores among 12 and 15 years old school children in different fluoride areas

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   Discussion Top


The study was conducted among the 12 and 15 years old school children in Nalgonda district, Andhra Pradesh, India, an endemic fluoride belt. The age groups of 12 and 15 years are among the index ages specified by WHO for assessing the severity of dental caries in children and adolescents. Moreover, these are also the two age groups where a reliable sample can be drawn from the school system. This prompted us in selecting 12 and 15 years old school children as the study participants. The range of optimum fluoride concentration for community water fluoridation is suggested to be 0.7-1.2 ppm in the literature. [14],[15] The fluoride concentration of less than 0.7 ppm is less than optimal as per the above cited range. So, the areas with less than 0.7 ppm Fluoride concentration were considered as low fluoride area. The areas with optimal range (0.7-1.2 ppm) were considered under medium fluoride area. The fluoride concentration of more than 4 ppm can cause severe dental fluorosis (characterized by confluent pitting or corroded appearance) and mild skeletal fluorosis. So, the fluoride concentration above optimal up to 4 ppm was considered as high fluoride area and more than 4 ppm as very high fluoride area. [15] This categorization above optimal range into high and very high fluoride areas was made to observe the influence of above optimal fluoride concentration on dental caries and to determine the concentration of fluoride that may increase the risk for dental caries in endemic fluoride belts. The literature suggests severe dental fluorosis with pitting to be a risk factor for dental caries.

The prevalence of dental caries and mean DMFT value were highest in low fluoride area followed by very high fluoride area and high fluoride areas in the descending order. The prevalence and the mean DMFT value were lowest in medium fluoride area having optimum fluoride concentration. With this, we can say that the maximum benefit from fluoride in terms of dental caries protection is derived where the fluoride concentration was optimal (0.7-1.2PPM). The fluoride concentration which is below optimal as well as above optimal will be detrimental.

The fluoridated water in medium and high fluoride areas offers topical benefit through frequent and repeated exposure. The studies in the past have demonstrated that the frequent exposure of the teeth to low concentration fluoride (fluoridated water and fluoride mouth rinses) reduces the risk for dental caries by facilitating remineralization of incipient carious lesions. The teeth in these areas (medium and high) will not show any alterations in the surface morphology (confluent pitting) but may have evidence of very mild to mild fluorosis. [16] These may be the possible explanation for the difference in the dental caries experience between low fluoride area and medium fluoride areas. [14] The prevalence of dental caries in very high fluoride area was almost equivalent to those found in low fluoride area. Here, although the drinking water containing high concentration of fluoride may give a topical fluoride benefit, the morphology of the teeth it-self will be altered. The teeth in these areas will have moderate to severe dental fluorosis with the surface enamel manifesting confluent pitting. These alterations in the surface characteristics of outer surface of enamel (roughened surface) may facilitate retention of plaque and food debris leading to dental caries initiation - a possible explanation for high dental caries experience in high and very high fluoride areas than compared to medium fluoride area. A study by Subba Reddy VV and Tiwari A (1992) [17] on the prevalence of dental caries in relation to fluoride levels of drinking water on a group of 1750 school children in the age group 12-17 years in Bhatinda district of Punjab, India found the prevalence to be lowest in areas where the fluoride concentration was 1.1 ppm (dental caries prevalence was 61.24%) and 2 ppm (dental caries prevalence was 54.72%). The dental caries prevalence was relatively high in areas where the fluoride concentration was 0.3 ppm (89.03%), 3.4 ppm (72.77%), 5.4 ppm (73.61%) and 10.4 ppm (85.47%). Here the dental caries prevalence in low fluoride area (0.3 ppm) and very high fluoride area (10.4 ppm) was significantly higher than that compared to medium fluoride areas. The results of our study were consistent with the findings of this study and others. [9],[18],[19],[20],[21],[22],[23],[24],[25],[26]

The prevalence of dental caries was more among females compared to males. The teeth erupt early among females compared to males. This early eruption may result in longer exposure of the teeth to deleterious oral environment among females. The study found no significant difference in the oral hygiene practices between male and female children in the present study. Lukacs et al., (2006) [27] summarized the results of meta-analyses on dental caries prevalence. They found the prevalence of dental caries to be more among females than males. They attributed the higher caries prevalence among females to the earlier eruption of teeth in girls, hence longer exposure of girls' teeth to the cariogenic oral environment, easier access to food supplies by women and frequent snacking during food preparation. Boys, because of greater body surface area and relatively greater physical activities tend to consume more water than compared to girls. This gives more frequent exposure to fluoridated water and thereby more topical fluoride effect among boys compared to girls. Singh DK, Singh RP (1981) [28] in their study among school going children in Patna found the prevalence to be high in female children (52.63%) than males (50.23%) similar to the results of our study.

The caries prevalence was more in 15 years group than 12 years group. Longer the duration of exposure of teeth to deleterious oral environment, greater will be the risk for dental caries. The study finding was in agreement with results of a study by Loyola et al.[26]

The prevalence and severity of dental fluorosis increased with increasing fluoride concentration. The higher the level of exposure of tooth during the developmental stages, to increasing concentration of fluoride in drinking water, greater will be the severity of fluorosis. [16],[29] The relation is strongly dose dependent. [4],[5],[8],[23],[30],[31],[32],[33] The results of our study were consistent with all these studies. There was no difference in the age and gender distribution of dental fluorosis. Dental fluorosis being a developmental defect affect the teeth at the time of calcification (before 10 years of age). Since the calcification for most of the permanent teeth except third molars is complete by 10 years of age, the exposure to systemic fluorides after this age will not have much influence in determining the severity of dental fluorosis. This finding was consistent with the findings of a study by Jackson et al., (1995) [34] who found no statistically significant difference in the mean TSIF (Tooth Surface Index of Fluorosis) scores between 7-10 years and 11-14 years group.


   Summary and Conclusion Top


The study found the prevalence of dental caries to be more in low and very high fluoride areas. The lowest prevalence was found in medium fluoride area with a fluoride concentration ranging from 0.7 to 1.2 ppm which is considered to be the optimum range for community water fluoridation. The caries prevalence was more among females and 15 years old children. The prevalence of dental fluorosis increased with increasing fluoride concentration with no difference in the age and gender distribution. The study results suggest that the fluoride concentration above optimal levels may not give any additional benefits in caries prevention but increase the risk of dental fluorosis. Though defluoridation plant was installed in Nalgonda, the plant is not functional at present. There is an immediate need for defluoridation at least in areas where the fluoride concentration is more than optimal levels (more than 1.2 ppm) as dental fluorosis is a major public health problem in these areas. While considering defluoridation in the district, the priority may be given to those areas where the concentration of fluoride is more than 4 ppm (very high fluoride area) as the fluoride concentration of more than 4 ppm increase the risk for both dental caries and dental fluorosis. Public private partnership in implementing the defluoridation process may be vital as the defluoridation plant maintenance had a setback when it was maintained by government sector alone in the past. A determined effort for defluoridation is the need of the hour in these areas.


   Acknowledgment Top


I would like to thank the Principal and management of Sri Sai College of Dental Surgery, Vikarabad, Andhra Pradesh, India for their continuous support and encouragement for undertaking this project. We thank the District Education Officer, Nalgonda, The Head masters of the schools concerned and the participants for their kind co-operation. With deepest sense of admiration and gratitude, I express my thanks to the faculty and Post graduate students in the department of public health dentistry, Sri Sai College of Dental Surgery for their help.

 
   References Top

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Correspondence Address:
B R Chandra Shekar
Department of Public Health Dentistry, People's Dental Academy, Bhanpur, Bhopal - 462 037, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1755-6783.127785

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