DRINKING WATER FLUORIDE AND CHILD DENTAL CARIES IN NOORABADEMAMASANI, IRAN

Transcription

1 187 Rahmani, Rahmani, Mahvi, Usefie 187 DRINKING WATER FLUORIDE AND CHILD DENTAL CARIES IN NOORABADEMAMASANI, IRAN Ayat Rahmani, a Kourosh Rahmani, b Amir Hossein Mahvi, c Masoud Usefie, d Tehran, Iran SUMMARY: The aim of this study was to determine whether a relationship exists between the groundwater fluoride (F) concentration and dental caries in children living in the Noorabademamasani area of Fars Province in Iran. The residents all have essentially the same socio-economic living standards and nutritional conditions. All 3349 children in the four age groups of 6 ( ), 9 ( ), 10 ( ), and 12 ( ) years were surveyed in seven village districts of the area. F levels in the drinking water measured by the SPADNS method ranged from 0.10 to 0.53 mg/l. The overall number of decayed permanent teeth ( ) per child ranged between 0.16 and 0.24, anhe number of decayed deciduous teeth (dt) ranged between 0.95 and Although the F level in the drinking water is below the national levels, the dental caries rates were also below the national levels. Linear regression analyses showed only a very weak decrease between the overall and scores and increasing water F levels in the seven village districts that are not statistically significant (R 2 = 0.159, p = 0.391, and R 2 = 0.280, p = 0.267, respectively). Keywords: Child dental caries; Fars Province, Iran; Fluoride in water; Noorabademamasani, Iran. INTRODUCTION Besides damaging bones aneeth, excessive intake of fluoride (F) is known to cause a wide range of adverse health effects, 1-5 F in drinking water is usually the main source of F intake and can cause many such effects. 6-9 Determination of water F concentration has therefore been an important undertaking in many countries to investigate its potential effects on health, especially in relation to the occurrence of dental caries and dental fluorosis The aim of this survey study was to examine the amount of dental caries in children in relation to the level of F in the drinking water in the Noorabademamasani area of Fars Province in Iran. MATERIALS AND METHODS The survey was conducted during the autumn and winter of in the Noorabademamasani area of Fars Province located in southwestern Iran as shown in Figure 1. The climate of Noorabademamasani is hot and dry in summer and mild in winter. The residents of the seven village districts selected for study all have essentially the same socio-economic living standards and nutritional conditions. For their drinking water they rely on local groundwater sources with varying concentrations of F. The selection of the seven village districts was also based on their having similar access to public health and dental care services. All the children in the four age groups of 6 ( ), 9 ( ), 10 ( ), and 12 a School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; b School of Public Health, Zabol University of Medical Sciences, Zabol, Iran; c For correspondence: School of Public Health and Center for Environmental Research, Tehran University of Medical Sciences, and Institute of Health Research, Ministry of Health, Tehran, Iran. ahmahvi@yahoo.com; d Noorabademamasani Health Care Center, Shiraz University of Medical Sciences, Shiraz, Iran.

2 188 Rahmani, Rahmani, Mahvi, Usefie 188 ( ) years were examined, making a total of 3349 children, including 1659 boys and 1690 girls. Figure 1. Location of Noorabademamasani in Iran anhe seven village districts surveyed: (1) Abpakhshan, (2) Jooijan, (3) Noorabad, (4) Babamonir, (5) Moorki, (6) Parin, (7) Mirjan. For the F analyses, the standard SPADNS method was used with a DR/2000s Spectrophotometer (HACH Company, USA). For the determination of dental caries, decayed permanent ( ) and deciduous ( ) teeth, but not filled or missing teeth, were recorded for each child in the above age groups in each village district according to the 1997 WHO criteria standards 13 by dentists from medical centers between October and February of Data were computerized and analyzed using the stata/es9. Linear regression analysis was useo examine the relationship between the F concentration in drinking water and caries in permanent and deciduous teeth. RESULTS AND DISCUSSION The population anhe number of children examined in each village district of the city are shown in Table 1, and in Table 2 the numbers of girls and boys in the four different age groups living in each of the seven district villages are recorded.

3 189 Rahmani, Rahmani, Mahvi, Usefie 189 Table 1. Seven village district populations and subject survey information in Noorabademamasani, Iran District Population Children examined Number of boys Number of girls Ratio girls/ boys Boys mean age Girls mean age Children mean age Abpakhshan Jooijan Noorabad Babamonir Moorki Parin Mirjan Table 2. Number of girls and boys in the four age groups in seven village districts of Noorabadem amasani, Iran District Age 6 years ( ) Age 9 years ( ) Age 10 years ( ) Age 12 years ( ) Girls Boys Girls Boys Girls Boys Girls Boys Abpakhshan Jooijan Noorabad Babamonir Moorki Parin Mirjan Totals As seen in Table 3, the concentration of F in the drinking water of the village districts was founo vary from 0.10 to 0.53 mg/l. Linear regression analyses show only a weak association between the water F levels anhe mean and in the seven village districts (Figure 2). When the outlying small village of Mirjan with 0.10 mg F/L in the water is omitted, the linear regression correlations for the remaining six village districts remain weak and nonsignificant statistically: R 2 = 0.221, p = for and R 2 = 0.286, p = for. Similarly, for elevation and, R 2 = 0.198, p = 0.317, and for elevation and, R 2 = 0.129, p = 0.429, which are also not statistically significant. In another study in Iran, we founhe F level in the groundwater ranged from 0.99 to 2.5 mg/l in one area and from 0.12 to 0.39 mg/l in another area. 14 In other studies in Iran, F water levels of up to 1.3 mg/l have been founo have little influence on lowering dental caries. 15 In Saudi Arabia it has even been reported F levels above 1 mg/l were associated with increased dental caries. 16

4 190 Rahmani, Rahmani, Mahvi, Usefie 190 Table 3. Elevation and decreasing water F level vs. dental caries in seven village districts of Noorabademamasani, Iran District Elevation above sea level (m) Fluoride (mg/l) Girls Boys Me an Abpakhshan Jooijan Noorabad Babamonir Moorki Parin Mirjan Figure 2. Linear regression analyses of drinking water F vs. the mean and in each village district of Noorabademamasani, Iran.

5 191 Rahmani, Rahmani, Mahvi, Usefie 191 Regression analysis also indicatehere is no significant correlation between increasing F water content and and in each age group (Table 4): age 6 group (R 2 = 0.418, p = 0.117) and (R 2 = 0.007, p = 0.857), age 9 group (R 2 = 0.522, p = 0.066) and (R 2 = 0.163, p = 0.368), age 10 group (R 2 = 0.418, p = 0.117) and (R 2 < 0.001, p = 0.988), and age 12 group (R 2 < 0.001, p = 0.921) and (R 2 = 0.160, p = 0.387). As a further illustration of the lack of a significant trenoward lower caries with increased levels of F in the drinking water, Figure 3 shows the linear regression analyses of the and data vs. the water F anhe age 12 group children in six of the seven village districts, omitting the small village of Mirjan with only 15 children in that age group. Although other constituents in the water may play a role in the dental caries of the children in this survey, resources to determine them were not available. Table 4. Child dental caries by gender and age in seven village districts in Noorademamasani, Iran, according to decreasing F content of the drinking water Fluoride (mg/l) Age 6 years ( ) Age 9 years ( ) Girls Boys Me an Girls Boys Me an Fluoride (mg/l) Age 10 years ( ) Age 12 years ( ) Girls Boys Girls Boys

6 192 Rahmani, Rahmani, Mahvi, Usefie 192 Figure 3. Linear regression analyses of water F and mean and in the age 12 group children in six of the village districts of Noorabademamasani, Iran (without Mirjan). Since no significant relationship between F levels in the drinking water and and was observed in this study, anhe caries scores are comparatively low and with no apparent connection with elevation, there would appear to be no neeo consider adding F to any of the water systems. A possible reason for the low rate of tooth decay in the seven village districts of Noorabademamasani is that, beginning ten years ago, all the children under age 12 have been served by the rural health center to receive and drink milk daily ano use mouthwash liquid regularly. Any need or desire for F is readily supplied by black tea and bottled water. 17,18 Where the concentration of F in drinking water sources is higher than the recommended maximum, removal of F can be achieved, for example, by the use of granular ferric hydroxide and Lewatite FO ,20

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