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Year : 2019  |  Volume : 30  |  Issue : 3  |  Page : 462-467
Prevalence of dental fluorosis among 12–15-year-old students in Enugu Metropolis, Nigeria

1 Department of Restorative Dentistry, Faculty of Dentistry, College of Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria
2 Department of Community Medicine, College of Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria
3 Department of Child Dental Health, College of Medicine, University of Lagos, Lagos, Nigeria
4 Department of Comprehensive Dentistry, University of Texas Health Sciences Centre, San Antonio, TX, USA

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Date of Web Publication9-Aug-2019


Background: Excessive ingestion of fluoride during tooth development, particularly at the maturation stage, may result in dental fluorosis, with clinical implications. Literature is scarce on dental fluorosis in Enugu, Nigeria. Purpose: The aim of this study was to assess the prevalence of dental fluorosis in Enugu, a major city in South East Nigeria. Materials and Methods: A multistage sampling technique was used to select a calculated sample of 400 students. A pretested interviewer-administered questionnaire was used to ascertain student's sociodemographic and related variables. The student participants were examined for dental fluorosis using Dean's index criteria according to the World Health Organization guidelines. Data were analyzed using SPSS version 16, and Chi-square test of association was used to compare proportions and ratios with significant level set at P < 0.05 and 95% confidence level. Results: Among the 400 students analyzed, 231 (57.8%) and 169 (42.2%) were male and female, respectively. Mean age was 13.43 ± 1.021 years. The prevalence of dental fluorosis was 11.3%, with the preponderance of very mild score (82.2%), and no observed severe dental fluorosis. The difference in the distribution of the scores of fluorosis among the children was highly statistically significant (χ2 = 72.80, P = 0.000). Dental fluorosis was found present in 39 (10.3%) of 378 users of fluoridated toothpaste and in 6 (27.7%) of the 22 users of nonfluoridated toothpaste. The differences in the presence and absence of dental fluorosis were statistically significant among users of fluoridated toothpaste. Conclusion: This study shows the prevalence of dental fluorosis to be low among secondary school students of Enugu metropolis.

Keywords: Enugu, fluoride, fluorosis, Nigeria, prevalence

How to cite this article:
Okoye LO, Ekwueme OEC, Sote EO, Amaechi BT. Prevalence of dental fluorosis among 12–15-year-old students in Enugu Metropolis, Nigeria. Indian J Dent Res 2019;30:462-7

How to cite this URL:
Okoye LO, Ekwueme OEC, Sote EO, Amaechi BT. Prevalence of dental fluorosis among 12–15-year-old students in Enugu Metropolis, Nigeria. Indian J Dent Res [serial online] 2019 [cited 2022 Aug 9];30:462-7. Available from:

   Introduction Top

Tooth decay over the years has been a major public health problem.[1] Fluoride has played a central role in oral health promotion for the past 50 years,[2] but the ingestion of excessive fluoride during tooth development, particularly at the maturation stage, may result in dental fluorosis which has an extensive range of clinical signs.[3] Mildly fluorosed enamel is fully functional and may present as barely detectable whitish surface striations, whereas severely fluorosed enamel is more prone to wear and fracture and may present as pitted, stained, and porous enamel described as mottling.

A number of studies [4],[5] have been carried out among the Caucasians to determine the prevalence of dental fluorosis. In certain parts of Africa, namely, Tanzania,[6] Kenya,[7] Uganda,[8] Sudan,[9] and South Africa,[10] fluorosis poses a serious public health problem. Williamson [11] and Ockerse [12] reported that 30%–45% of the Kenyans in East Africa are affected to various degrees by fluorosis. Some reports from sub-Saharan African countries have shown that the disfiguring and disabling impacts of dental fluorosis are significant to people's quality of life.[13]

In Nigeria, however, there are limited data on dental fluorosis and fluoride content of drinking water.[14] Akpabio [15] in a nationwide survey recognized that there exist foci of endemic fluorosis in some parts of Nigeria. He noted particularly that the Langtang community of Plateau State had the highest fluoride level of 2.4 mg/L. Wongdem [16] went further to map out areas of fluoride concentrations in water in that same community.

There are no documented data on dental fluorosis in Enugu, Nigeria, and there is no known study carried out on dental fluorosis in this eastern part of the country till date. Therefore, the purpose of the present study was to determine the prevalence of dental fluorosis among 12–15-year-old secondary schoolchildren in Enugu metropolis with the aim of providing a baseline data for monitoring dental fluorosis in Enugu.

   Materials and Methods Top

Selection of subjects

This study was conducted in Enugu metropolis, which by its position as the former capital of Eastern Nigeria reflects the demographic picture of the people of the South Eastern zone of Nigeria. It is a cosmopolitan area made up of a people with varying demographic indices. The target population was 12–15-year-old secondary schoolchildren of both genders. This is a descriptive epidemiological study with cross-sectional design type. A multistage sampling technique was used to select 400 students who participated in the study. From the 62 registered private and public secondary schools in the three local government areas that make up the Enugu metropolis, five secondary schools were randomly selected. In each school, eight classes were selected, and ten students within the age of 12 and 15 years were randomly selected from each class using the table of random numbers. Children who had fixed orthodontic appliance, tooth surfaces that had restorations covering <25%, or teeth grossly covered with calculus were excluded in this study. The survey instrument is a pretested interviewer-administered questionnaire, with open- and closed-ended questions, comprising ten questions and a chart table arranged in three sections. The first section is the sociodemographic characteristics of the respondents, while the second section is for the risk factors for dental fluorosis. The third section is exclusively for clinical examination for dental fluorosis.

Sample size calculation

Enugu metropolis which comprises Enugu East, Enugu North, and Enugu South has a total population of 152,416 by the National Population Census of 2006.[17] In each of the three local government areas, the total student enrollments for junior and senior secondary schools each, in both private and public schools, vary from 3000 to 10,000 students.[18] In the public schools, enrollment by class, junior and senior secondary each, ranges between 800 and 4000 students, whereas in the private schools, it ranges from 300 to 4000 students.[18]

The sample size of 400 was determined using the formulae [19] for sample size estimation for population <10,000

n = The minimum sample size

Z = The standard deviation set at 1.96 for 95% confidence level

P = Prevalence of dental fluorosis in a previous study [16] =51%

Q = Percent difference in the prevalence value = 49%

D = The tolerance error margin set at 5% = 0.05

Minimum sample size = 384

The sample size was increased to 400 to improve precision and reduce error margin.

Ethical clearance and informed consent

The study was approved by Health Research Ethics Committee of the University of Nigeria Teaching Hospital, Enugu, with registration number UNTH/CSA/329/OL.5. Written informed consent was obtained from the school authorities, while oral informed consent was obtained from the parents of each child as well as from the children themselves.

Questionnaire administration and clinical examination

The survey instrument was pilot tested among students from similar schools, with similar characteristics to the local government areas of the study. To ensure accurate and correct application of the research procedures through interviewers' practice, three interviewers and a primary examiner were trained and calibrated by a benchmark interviewer/examiner (the principal investigator) on the administration of the questionnaires and fluorosis detection. Fifty students, with (n = 20) and without (n = 30) fluorosis, from the schools used for pretesting the survey instrument, were recruited for the calibration exercise. The agreement between the examiner and calibrator (interexaminer agreement) and the examiners' individual repeated exercise (intraexaminer agreement) were evaluated using the unweighted kappa (κ) statistic. The three trained interviewers administered structured questionnaires, to elicit risk factors, such as sources of drinking water, use of fluoride supplements, fluoride dentifrices (toothpastes and mouth rinses), and history of other topical fluoride applications. One calibrated researcher conducted the examinations. Measurement of dental fluorosis was based on Dean's index criteria,[20] according to the World Health Organization guidelines as shown in [Table 1]. The examinations were carried out in good natural light on sunny days facing a window. Teeth were dried with cotton rolls before the examinations. Recordings were made on the basis of two most affected teeth.
Table 1: Dean's index criteria for measurement of dental fluorosis according to the World Health Organization guidelines

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Analysis of fluoride in the drinking water

Drinking water samples were collected from the various drinking water sources of the study participants. Using the colorimetric method, the fluoride concentration of the collected water was analyzed at the Department of Pure and Applied Chemistry, University of Nigeria, Nsukka.

Statistical analysis

Data from the questionnaire and clinical examinations were analyzed using the Statistical Package of the Social Science (SPSS Inc., version 16.0, Chicago, Illinois, USA). Chi-square test of association was used to compare proportions and ratios with significant level set at P < 0.05 and 95% confidence level.

   Results Top

A total of 400 secondary schoolchildren, 169 (42.2%) males and 231 (57.8%) females between the ages of 12 and 15 years, participated in this study. There was 100% compliance with filling of the questionnaires. All the participating children and their parents gave informed consent. The age distribution is as shown in [Table 2] with a mean age of 13.43 ± 1.021. Two hundred and sixteen (54%) mothers of the children in the study population had postsecondary education, 130 (32.5%) had the secondary education, 45 (11.3%) had primary education, whereas 9 (2.2%) had no formal education.
Table 2: Age distribution of respondents

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The intraexaminer agreement values (unweighted κ value) for the three interviewers, respectively, were 0.80, 0.87, and 0.91 for administration of questionnaire and 0.90, 0.89, and 0.94 for fluorosis detection. The mean interexaminer reliability values comparing the benchmark examiner versus each of the three interviewers were 0.72, 0.80, and 0.81 for administration of questionnaire and 0.82, 0.87, and 0.88 for dental fluorosis detection, respectively. These values met the target set for acceptability before the training and calibration.

[Table 3] shows the sources of drinking water used by the participants. Soft drinks were taken by 99.95% of the children. The use of fluoride supplement is shown in [Table 4]. Fluoridated toothpaste was used by 378 (94.8%) of the children, while 22 of them (5.5%) used nonfluoridated toothpaste. Fourteen (3.5%) children have taken fluoride tablet, while 366 (91.5%) have never taken. Twenty (5.0%) children did not know if they have taken fluoride tablets in the past or not. Ten (2.5%) children have been treated with fluoride gel or solution, while 363 (90.8%) have not been so treated. Twenty-seven (6.7%) children did not know if they have been treated with fluoride gel or solution in the past. Sixty-two (15.5%) children had the history of visiting the dentist for dental checkups and dental problems, while 338 (84.5%) have never been to the dentist.
Table 3: Sources of drinking water and soft drinks in relation to dental fluorosis

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Table 4: Fluoride supplements in relation to dental fluorosis

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The prevalence of dental fluorosis in this study was 11.3%. Of the 45 children who had fluorosis, 37 (82.2%) had the very mild score, while 5 (11.1%) had the mild score and 3 (6.7%) had the moderate score. No child examined had severe dental fluorosis [Table 5].
Table 5: Severity of dental fluorosis among the children

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Eighteen (40%) children with dental fluorosis were 13 years of age, while 12, 14, and 15 years consisted of 9 (20%) children each [Table 2]. The mean age of children with fluorosis was 13.4 years (±1.03 years) while that of children without fluorosis was 13.5 years (±1.1 years). There was no statistically significant difference in the mean ages of children with dental fluorosis and those without (P = 0.56).

Twenty-six (57.8%) children with dental fluorosis were female while 19 (42.2%) were male. There was no statistically significant difference in the gender of children with dental fluorosis and those without dental fluorosis. Eighteen (40%) mothers of children with dental fluorosis had postsecondary education, 22 (48.9%) had secondary education, while 5 (11.1%) had only primary education. There is no statistically significant difference in the educational level of mothers of children with dental fluorosis and those without.

Forty-four (97.8%) children with dental fluorosis drank sachet or bottled water, 41 (91.1%) drank tap water, 28 (62.2%) drank rainwater, 9 (20%) drank stream water, while 2 (4.4%) children drank water from the well. All children with dental fluorosis took soft drinks [Table 3].

With regard to fluoride dentifrices, 39 (86.7%) children who had dental fluorosis used fluoridated toothpaste while 6 (13.3%) used nonfluoridated toothpaste [Table 4]. There is a statistically significant difference in the type of toothpaste used by children with dental fluorosis and those without (P = 0.014). Only one (2.2%) child among those with fluorosis had taken fluoride tablet, 42 (93.4%) had never taken, whereas 2 (4.4%) children did not know if they had taken fluoride tablet or not. Only one (2.2%) child had also been treated with fluoride gel while 41 (91.1%) children had never been treated with fluoride gel or solution. Three children did not know if they had been treated with fluoride gel or not [Table 4].

Five (11.9%) of the children with fluorosis had visited the dentist for dental checkup or treatment while 40 (88.9%) have never visited dentist. Although when compared with children without fluorosis, there is no statistically significant difference (P = 0.388) in the visitation pattern and dental fluorosis.

All samples of drinking water and soft drinks analyzed had approximately the same constant of fluoride (0.30–0.33 mg/L).

   Discussion Top

In this study, the age range 12–15 years was used basically because all the permanent teeth except the last molars would have erupted. This is consistent with the age group studied in a previous study.[13] However, the age distribution differs from that of Wongdem et al.[14] whose sample population cuts across a wider age range, varied occupations, and socioeconomic backgrounds.

Socioeconomic status of the children was determined by their mothers' educational level. This is due to difficulty posed by the varied fathers' occupations in grouping into different income levels. Burt et al.[21] also used only mothers' educational level to determine socioeconomic status of children studied. Educational levels of mothers are important in children's oral health since they are usually responsible for supervising and imparting primary oral hygiene practices. The majority (86.5%) of the mothers in this study were educated to secondary level and above. This may be due to the fact that Enugu is an urban city, a cosmopolitan area, with high literacy level (84%).[19] Most children in this study used fluoridated toothpaste, and this is because fluoridated toothpaste is readily available in the Nigerian market.

The majority of the children in study population have never attended the dental clinic for checkup or any dental treatment. Some children confessed to the researcher of their ignorance of routine dental checkup. This, therefore, explains the uncommon use of fluoride supplements (gel, solution, tablets, and rinses) in this study.

Almost all the children studied took soft drinks and all had more than one source of drinking water. Enugu previously depended mainly on tap water supply that has become so irregular. There is one mainstream that flows through Enugu and supplies different parts of the city. All sources of water analyzed had fluoride level of 0.30–0.33 mg/L. The value is very low compared to the findings of Wongdem et al.[14] in Langtang, Jos, a city located in the Middle Belt region of Nigeria, where different sources of water gave varied fluoride levels with values ranging from 0.5 to 3.96 ppm.

Forty-five (11.3%) children in the population studied had dental fluorosis. This prevalence was observed taking into consideration scores 2–5 according to Dean's classification.[22] However, just considering the fluorosis levels that determine esthetic compromise (mild, moderate, and severe), this percentile was 2%. The predominant level was the very mild (9.25%), followed by the mild (1.25%) and then the moderate level (0.75%) [Table 5]. There is no severe dental fluorosis observed in this study; however, three (0.75%) children had moderate fluorosis. The number of children affected decreased with increase fluorosis score. The prevalence of 11.3% found in this study was low compared to 51% prevalence reported by El-Nadeef and Honkala [23] in Central Nigeria with water fluoride level of between 0.0 and 0.4 mg/L. There are several recent reports of dental fluorosis in areas of low fluoride levels.[24] However, the distribution of fluorosis score agrees with that of this study. El-Nadeef and Honkala [23] found predominantly (42%) very mild fluorosis while the remaining 9% is accounted for by mild and moderate fluorosis. Their findings differ from that of Wongdem et al.[14] in Langtang town, Nigeria, in which 26.1% prevalence rate of enamel fluorosis was reported. About 20.6% of the cases were classified as moderate and 5.5% as severe, all posing esthetic problems. The higher prevalence of esthetically disturbing scores in the Langtang study is due to high fluoride levels measuring up to 3.96 ppm found in selected water sources. Differences found between this study and that of Central Nigeria by El-Nadeef and Honkala [23] could be due to differences in diet, climate, and altitude.[14] In addition, the Thylstrup and Fejerskov index used could be responsible for the higher percentage observed by El-Nadeef and Honkala [23] since the index had been suggested to give higher fluorosis prevalence than Dean's index.[25]

In the present study, there was no significant association between dental fluorosis and age, sex, or socioeconomic status of the children.

With the exception of toothpaste, no relationship could be established between dental fluorosis and the use of other fluoride products [Table 4]. Mascarenhas [26] reported that early toothbrushing with fluoride toothpaste has a significant relationship with dental fluorosis. In doing so, parameters such as beginning toothbrushing at a relatively early age, the amount of toothpaste used, measured as either toothbrush frequency, amount swallowed, or the amount of paste used at each brushing were considered. However, these variables were not investigated in this study.

   Conclusions Top

The prevalence of dental fluorosis is low among secondary school students of Enugu metropolis. The statistically significant difference observed in the type of toothpaste used by children with dental fluorosis and those without implies that there is a need to encourage supervision of the use of fluoridated toothpaste by children below 5 years of age, through public awareness programs in Enugu. However, with the level of fluorosis found in this study in an area with 0.3 mg/L fluoride in drinking water, there could be contributory effects from other sources of fluoride that may require further investigation.

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Conflicts of interest

There are no conflicts of interest.

   References Top

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Correspondence Address:
Dr. Osa-Eloka Christiandolus Ekwueme
Department of Community Medicine, College of Medicine, University of Nigeria, Nsukka, Enugu State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.IJDR_498_17

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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