Caries prevalence among secondary school children in

Riyadh and Qaseem

Abdullah M. AlDosari,* BDS, MSD, PhD    Amjad H. Wyne,** BDS, BSc, MDS, FASDC
Enosakhare S. Akpata,***  BDS, MDS, FDSRCPS, FWACS    Nazeer B. Khan,** MSc, PhD

* Dept. of Maxillofacial Surgery and Diagnostic Dental Sciences, ** Dept. of Preventive Dental Sciences, College of Dentistry, King Saud University, Riyadh, KSA
*** Dental School University of Kuwait, Kuwait

The aim of this study was to describe the caries prevalence and severity in secondary school children in Riyadh and Qaseem regions and, to correlate caries experience with fluoride levels in the drinking water. A total of 734, 15- to 19-year-old (Mean 16.4, SD 1.2 years) secondary school children from areas of various water fluoride levels were examined in Riyadh (236 male and 193 female) and Qaseem (163 male and 142 female), utilizing the World Health Organization (WHO) criteria for the diagnosis of dental caries. Results showed the prevalence of dental caries as 91.1% in Riyadh and 90.5% in Qaseem. The mean DMFT score in Riyadh was 7.35 (SD 4.99), with D component of 6.28, M component of 0.32 and F component of 0.75. The mean DMFT score in Qaseem was 7.05 (SD 4.58) with D component of 6.02, M component of 0.46 and F component of 0.56. The overall data showed no significant difference (P > 0.05) in mean DMFT scores at various fluoride levels. However, low values of DMFT were found in two fluoride zones (0.61 - 0.80 ppm and 0.81 - 1.50 ppm). It was concluded that the caries prevalence was very high among the students studied in Riyadh and Qaseem regions. However, there was no linear correlation between the caries experience and water fluoride level in both Riyadh and Qaseem regions.

The role of fluoride in the prevention of dental caries is very well established.1,2 Dean et al.3 in 1942 reported an inverse relationship between caries prevalence and drinking water fluoride levels. Since then, a large number of studies have confirmed the beneficial effects of fluoride in the drinking water.4-7

Recent studies have reported an alarmingly high caries prevalence in Saudi preschool, primary and intermediate school children.8-10 However, there have been no reports on the caries prevalence and severity in secondary school children aged 15-19 years.

A study was recently conducted to determine the fluoride level of drinking water in Riyadh and Qaseem regions, and fluoride levels were found to be between 0.00 and 6.2 parts per million (ppm).11 An additional component of the survey was the examination of secondary school children for dental caries. The objective of this paper was to determine the caries prevalence and severity in the secondary school children of Riyadh and Qaseem regions and, to correlate the caries experience with fluoride levels in the drinking water.

The information about the population of secondary school children was obtained from the Ministry of Education and the Presidency of Girls' Education.12 The students' sample size was determined utilizing the sample size formula for estimating mean.13

Utilizing a map prepared from the water analysis study,11 zones with similar water fluoride concentrations were identified. The list of these zones was considered as the sampling frame for the subjects. Some municipalities were randomly selected in each zone to represent the population in each of the zones. One or more secondary schools for both boys and girls were then selected depending on the sample size requirement. All the subjects were Saudi nationals and permanent residents of the area. The distribution of the sample size between the different fluoride concentration zones was based on the percentage of population residing in each zone.11

All the selected students were examined for dental caries utilizing the WHO criteria for the diagnosis of dental caries.14 The data were entered into a computer using FOXPRO software and a data file generated. The data were then analyzed utilizing Statistical Package of Social Sciences (SPSS). The one-way analysis of variance (ANOVA) and Student t test were used to test the difference between means. Each examiner was calibrated with one of the authors (ESA). Intra- and inter-examiner reliabilities were determined using Kappa statistics. A high degree of agreement (above 0.9) was demonstrated between the reference examiner and the five field examiners for DMFT. The intra-examiner reliability of all the field examiners was also high (above 0.9). A Kappa value of 0.8 and above indicates excellent agreement.

A total of 734 secondary school children were examined in Riyadh (236 male and 193 female) and Qaseem (163 male and 142 female) with the mean age of 16.4 (SD 1.2) years and a range of 15-19 years. The distribution of the sample between the different fluoride zones is shown in Table1.

The prevalence of dental caries was 91.1% in Riyadh and 90.5% in Qaseem, respectively. The mean DMFT score in Riyadh was 7.35 (SD 4.99), with D component of 6.28, M component of 0.32 and F component of 0.75. The mean DMFT score in Qaseem was 7.05 (SD 4.58) with D component of 6.02, M component of 0.46 and F component of 0.57. There was no significant gender difference in terms of mean DMFT scores in Riyadh, whereas in Qaseem, the DMFT score was significantly higher (P <0.05) in male children compared to female children (Table 2).

Table 3 describes caries experience (DMFT) of the children in relation to various water fluoride levels. The overall data showed no significant difference (P > 0.05) in mean DMFT scores at various fluoride levels. However, low values of DMFT were found in two fluoride zones with fluoride concentration of 0.61 - 0.80 ppm and 0.81 - 1.50 ppm, respectively.

The caries prevalence was found to be very high among the students studied in Riyadh and Qaseem regions. The results were not surprising for Riyadh region as the majority of the study population lives in low water fluoride level areas.11 However, the results were unexpected in Qaseem where a majority lives in the area of near optimum or high fluoride areas.11  In Qaseem, the lowest DMFT score was found in children from lowest water fluoride level and higher DMFT from optimum water fluoride level. Several factors could possibly be responsible for the result. Caries related risk factors such as oral hygiene and dietary practices could have diluted the effects of fluoride exposure in high fluoride population.15 The high fluoride exposure also results in higher incidence of dental fluorosis, which may make it difficult to distinguish between the tooth destruction caused by severe fluorosis and by dental caries. On the other hand, healthy oral hygiene and dietary habits in low water fluoride population may be responsible for low caries experience. Lack of knowledge about the actual source of drinking water in individuals may also be responsible for the lack of linear relationship between water fluoride level and caries experience. The sample in the present study was randomly selected, proportionally to the number of children from various fluoride levels, which might have affected the results.

Several studies have reported low caries experience with increasing level of fluoride in the drinking water,16,17 However in the present study, a linear correlation could not be established between the caries experience and water fluoride level in both Riyadh and Qaseem regions. As mentioned earlier, the other caries risk factors such as diet and oral hygiene practices may have been superimposed upon the fluoride factor. The results of the present study rather showed high DMFT scores in high fluoride areas. Several other studies have also reported similar results in many parts of the world.17,18 However, it must be mentioned that some researchers have concluded that a much greater protection against dental caries could result from higher fluoride concentrations (5-7 ppm) than is customarily recommended as best for prevention of dental caries.19

Dental decay was the major component of the DMFT scores in this study both in Riyadh and Qaseem. Several studies in younger children of Riyadh have also reported the "D" as the major component of DMFT/dmft scores.8-10, 20  Such a large proportion of untreated caries indicates very high restorative needs of the study population. A considerable effort will be required to provide restorative services to this population. A well-organized school dental health service could be a possible solution to the problem. Such a service will not only provide sufficient restorative services to these children, but will also constitute effective prevention programs for dental caries.

This study has provided important base-line data about caries experience and its relevance to various fluoride levels in secondary school children in Riyadh and Qaseem regions of Saudi Arabia. It is hoped that the results will help in planning an effective preventive and restorative services in the regions.

The study was funded by King Abdulaziz City of Science and Technology (KACST) Grant No. 49-17-TA.

Address reprint requests to:

Dr. Amjad H. Wyne
Department of Preventive Dental Sciences
College of Dentistry, King Saud University
P.O. Box 60169, Riyadh 11545, KSA
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