Original Paper Received: August 16, 2014 Accepted: November 9, 2014 Published online: February 6, 2015
Caries Res 2015;49:184–191 DOI: 10.1159/000369864
Effects of Water Fluoridation on Caries Experience in the Primary Dentition in a High Caries Risk Community in Queensland, Australia Rongzhen Koh a Margaret L. Pukallus b Bruce Newman b Michael Foley c Laurence J. Walsh a W. Kim Seow a
a
Centre for Paediatric Dentistry, The University of Queensland School of Dentistry, Herston, b Metro South Oral Health Services, Queensland Health, Kingston, and c Metro North Oral Health Services, Queensland Health, Brisbane, Australia
Abstract Objectives: In December 2008, artificial water fluoridation was introduced for the first time to the Logan-Beaudesert district in the state of Queensland, Australia. The aim of this study was to evaluate the effects of water fluoridation in the primary dentition in this community after a period of 36 months. Methods: Children aged 4–9 years with clinical examinations and bitewing radiographs (BWs) taken before water fluoridation (pre-F) were randomly selected as comparison controls for age matched children who had been exposed to a mean period of 36 months of water fluoridation (post-F). A total of 201 sets of pre-F BWs from children (mean age 6.95 ± 1.05 years) and 256 sets of post-F BWs from children (mean age 7.19 ± 1.23 years) attending schools in the district were randomly selected. Caries experience in the primary dentition was determined as decayed, missing or filled teeth/surfaces (dmft/dmfs). Results: The caries prevalence for the pre-F group was 87% compared to 75% in the post-F group (Odds ratio (OR): 0.44, 95% CI: 0.27–0.72). Overall, there was a 19 percent reduction of mean dmft from 4.54 in the pre-F group to 3.66 in the post-F group (p = 0.005). After fluoridation, the dmfs was reduced from 6.68 to 5.17 (p = 0.0056). The distal surfaces of maxillary first primary molars
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experienced the greatest reduction (26%) in caries experience after water fluoridation (p < 0.001). Conclusions: After only 36 months of water fluoridation there was a significant drop in caries prevalence from 87 to 75% and a 19% reduction in caries experience in a community with one of the highest caries rates in Australia. © 2015 S. Karger AG, Basel
Introduction
Water fluoridation is a cost-effective and safe method of caries prevention, and has provided benefits to many communities in Australia [Armfield, 2008; Cobiac and Vos, 2012; Slade et al., 2013]. While most technologybased advances in caries prevention tend to benefit to a greater extent those who have ready access to dental services, water fluoridation indiscriminately protects an entire community regardless of socioeconomic status [Armfield, 2008]. Prior to the introduction of water fluoridation in 2008, only 5 percent of children in the state of Queensland in Australia had access to fluoridated water, compared to approximately 86 percent of the rest of the country [Armfield, 2006]. However, within two years after a large scale rollout of water fluoridation commencing in 2008, 80% of the state’s population had access to optimally fluoridated water, with an adjusted fluoride concentration between 0.6 and 0.8 mg/l. Prof. W. Kim Seow University of Queensland, Centre for Paediatric Dentistry School of Dentistry, Oral Health Centre, 288 Herston Road 4006 Herston (Australia) E-Mail k.seow @ uq.edu.au
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Key Words Water fluoridation · Caries experience · Primary dentition · Low socioeconomic
aminations in children aged 4.0–9.9 years who attended primary schools in the Logan district in the state of Queensland, Australia. The target population is considered low socioeconomic, with an unemployment rate (2013) of approximately 8% (compared with 6% for Queensland) and 31% of residents in the most disadvantaged quintile (compared with 20% in Queensland state) [Queensland Government Statistician’s Office, 2014]. The radiographs used in the study were exposed as part of the routine dental care of the children, and oral health and demographic information were obtained from existing records. All children in the study received regular dental care from the public dental clinics in the Logan-Beaudesert clinics during the period 1998 to 2013. For the pre-fluoridation (pre-F) data, a random sample of dental records of 4- to 6- and 7- to 9-year-old children who had attended routine dental treatment visits under the district’s public oral health program from 1998 to December 2008 was collected. The dental records were selected by an independent research assistant who was not part of the study. As the dental records including BWs were stored in cabinets with the children’s names by alphabetical order, the randomisation was performed by selecting the first two records from every alphabet that fitted the inclusion criteria, and repeating the process until the required numbers of children were obtained. The dental examinations and BW radiography were performed by dental clinical staff according to standard clinic policy and guidelines [Ford et al., 2009; Newman et al., 2009]. Inclusion criteria for the study were age of 4–9 years at the time of radiographic examination, and BWs of diagnostic quality. Exclusion criteria were developmental dental abnormalities such as enamel defects, and serious chronic medical conditions, such as congenital heart disease. Demographic details and oral health information collected for the study included gender, date of birth, medical history and date of BW radiographs. The post-fluoridation (post-F) data were obtained from dental examinations data and BW records of 4- to 9-year-old children from the same clinic who had the BWs and clinical data recorded at dates between January 2011 and December 2012. To standardise the diagnostic quality of the BWs, each set of radiographs was mounted on a light box and photographed with a Canon EOS-D60 SLR camera (Canon, Tokyo, Japan) with a 100 mm Canon Macro EF lens. Shutter speed was fixed at 1/90 and aperture at 5.6. The images were viewed under standardised settings in a computer using Adobe Photoshop CS software (Adobe Systems Inc., San Jose, Calif., USA).
Ethical clearance for the study was obtained from The University of Queensland School of Dentistry and Queensland Health human research ethics committees. The study assessed caries experience using the results of dental radiographs and clinical ex-
Scoring of BW Radiographs The proximal and occlusal tooth surfaces of the maxillary and mandibular primary molar teeth were scored using a modification of the scoring scale described by Pitts and applied by Morgan et al. (table 1) [Morgan et al., 2008; Pitts, 1985]. Caries experience was measured as caries present in dentine, recurrent caries or restored surfaces (table 1) [Morgan et al., 2008; Pitts, 1985]. BWs with overlapped proximal surfaces and other defects that rendered the surfaces unreadable, such as cone-cutting, were excluded from the study. All radiographs were scored blind by a single author (RK). A split screen was used to simultaneously score each radiograph and input data into a custom-designed database. To assess intra-examiner variability for caries assessment, 10 sets of BWs were scored twice, two weeks apart. The examiner’s kappa statistic score was
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
Caries Res 2015;49:184–191 DOI: 10.1159/000369864
Methods
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Before water fluoridation, 6 year-old children residing in Logan-Beaudesert, a district with one of the lowest socioeconomic status in the state of Queensland, had a mean caries experience (decayed, missing, filled teeth, dmft) index of 4.9, which is two and a half times that of the rest of Australia [Ha et al., 2013; Newman et al., 2009; Public Health Information Development Unit Australia, 2007]. The high costs of dental treatment for caries in young children place large personal and financial burdens on the children and the community [Casamassimo et al., 2009] and demonstrate the pressing need for caries prevention in this district. The effectiveness of water fluoridation for preventing dental caries has been researched extensively, with documented benefits for both primary and permanent dentitions [Rugg-Gunn and Do, 2012; Slade et al., 2013]. Previous Australian studies have reported caries reductions in the range of 10–69% in the primary dentition in children exposed to optimum water fluoridation [Rugg-Gunn and Do, 2012]. The majority of these studies, however, report on cross-sectional findings and relied on complex statistical analyses to adjust for confounding factors. Furthermore, in most studies which examined caries experience, BW radiographs were not used, which most likely led to underreporting of caries prevalence [Newman et al., 2009]. As the preventive effects of water fluoridation are thought to be the highest on smooth (proximal) surfaces, information from BWs should be added to data from the clinical examinations to ensure complete documentation of caries. In addition, there have been only a few studies that examined the preventive effects of water fluoridation on low socioeconomic children [Jones and Worthington, 1999; McLaren and Emery, 2012; Slade et al., 1996]. As early childhood caries is one of the most challenging conditions in paediatric dentistry today, it is of clinical and public health significance to determine the effects of water fluoridation on children who are most at risk to develop early childhood caries. Therefore, the aim of the present study was to evaluate the effects of water fluoridation on the caries experience of the primary dentition of 4- to 9-year-old children living in the high caries-risk, low socio-economic community of Logan-Beaudesert.
Table 1. Radiographic diagnostic scoring system and criteria for proximal caries
Score
Category
Diagnostic criteria
0
Sound
No radiolucency or restoration visible
1
Outer-half enamel lesion
Zone of increased radiolucency confined to outer half of enamel (no minimum limit)
2
Inner-half enamel lesion
Zone of increased radiolucency involving inner and outer half of enamel, including lesions extending up to but not beyond the dentinoenamel junction
3
Outer-half dentine lesion
Zone of increased radiolucency penetrating enamel and dentinoenamel junction but confined to outer half of the dentine
4
Inner-half dentine lesion
Zone of increased radiolucency penetrating into the inner half of dentine with or without pulpal involvement
5
Unreadable overlap
Unable to score surface due to overlap
6
Secondary caries
Zone of increased radiolucency associated with previously restored surface
7
Filled surface
Radiographic appearance consistent with restoration
8
Not visible
Tooth not visible on radiograph
Adapted from Morgan et al. [2008] and Pitts [1984].
Sample Size Calculations A sample size calculation found that 97 children in each of the pre- and post-fluoridation groups were required to produce an 80% power to detect a significant difference at the 0.05 level if 60% caries prevalence is reduced to 40% after the introduction of water fluoridation. To assess the caries experience, a sample size of 63 is required to have an 80% power to detect a change of dmft/dmfs from 3 pre-fluoridation to 2 after fluoridation at the 0.05 level [Fleiss et al., 2003]. Data Analysis The decayed, missing and filled teeth/surface (dmft/dmfs) index was used to assess the caries experience (table 1). A surface was classified as decayed (d) if the lesion progressed beyond the dentinoenamel junction. Carious lesions restricted to the enamel were not included [Wenzel, 1995]. The missing (m) component of primary dentition was based on guidelines set by Palmer et al. [1984], which include all missing primary molars in children aged 9 and missing primary incisors for children younger than 5 years. A molar was considered to have 5 and an incisor 4 surfaces [Palmer et al., 1984]. Missing primary incisors in children 5–7 years of age were considered to be exfoliated [Palmer et al., 1984]. The dmft/ dmfs indices were calculated from clinical records and BWs. Statistical Analysis The Mann-Whitney test was used to compare pre-F and post-F groups with respect to mean dmft and dmfs scores and the Fisher’s exact test was used to assess caries prevalence. Odds ratios and 95%
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confidence intervals were calculated using the frequency ratios to compare the pre- and post-fluoridation caries prevalence. Analyses were performed with InStat software (GraphPad Software Inc., La Jolla, Calif., USA). Significance tests were two-tailed at the 0.05 probability.
Results
Overall, a total of 201 pre-F and 256 post-F sets of BWs and dental records from 457 children were included in the study. Demographic data for the children are presented in table 2. The post-F group had been exposed to water fluoridation for a mean time period of 36.55 ± 6.53 months before the BWs were taken. The mean age ± SD of pre-F and post-F children was 6.95 ± 1.05 and 7.19 ± 1.23 years respectively (table 2). Table 3 shows the caries prevalence of the pre-F and post-F children. As shown in table 3, the pre-F group, 175 (87%) of the children showed caries experience (dmft >0) compared to 191 (75%) in the post-F group The odds for post-F children to experience decayed, missing or filled teeth were significantly lower than the pre-F children (OR = 0.44, 95% CI: 0.27–0.72). Table 4 shows the mean dmft scores of primary and permanent teeth in pre-F and post-F children. The mean total post-F dmft scores of the 4.00–6.99 and 7.00–9.99 year old children represented reductions of 22 and 17% compared to the respective pre-F mean scores. Overall, Koh/Pukallus/Newman/Foley/Walsh/ Seow
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0.91 for intra-examiner consistency, indicating excellent agreement. Inter-examiner variability was tested between the first and last author (WKS), a specialist paediatric dentist, using 20 sets of BWs, and yielded a kappa statistic score of 0.89, indicating high inter-examiner consistency.
Table 2. Mean ages of children and exposure time periods to water fluoridation
Age, years 4.00–6.99 Pre-F Post-F 7.00–9.99 Pre-F Post-F Total (4.00–9.99) Pre-F Post-F
n
Mean age, years (±SD)
Mean period of time exposed to water fluoridation, months (±SD)
99 131
6.07±0.56 6.18±0.61
36.21±6.37
102 125
7.81±0.63 8.25±0.73
36.87±6.69
201 256
6.95±1.05 7.19±1.23
36.55±6.53
SD = Standard deviation; Pre-F = pre-fluoridation; Post-F = post-fluoridation.
Table 3. Prevalence of children with dmft greater than zero in the pre- and post-fluoridation groups
Age, years
4.00–6.99 7.00–9.99 Total (4.00–9.99)
Pre-fluoridation
Post-fluoridation
n
caries affected, n (%)
n
caries affected, n (%)
99 102 201
83 (84) 92 (90) 175 (87)
131 125 256
99 (76) 92 (74) 191 (75)
p value*
Odds ratio post-F/pre-F (95% CI)
0.14 0.0019 0.0009
0.60 (0.31–1.16) 0.30 (0.14–0.65) 0.44 (0.27–0.72)
* Fisher’s exact test. CI = Confidence interval.
Table 4. Caries experience (mean number of decayed, missing and filled teeth/surface) (dmft/dmfs) in the pre-fluoridation (pre-F) group
and post-fluoridation (post-F) groups of children Pre-F, age (years)
n Mean dmft (±SD) Median dmft (Q1, Q3) p value comparing post-F and pre-F dmft* Mean dmfs (±SD) Median dmfs (Q1, Q3) p value comparing post-F and pre-F dmfs*
Post-F, age (years)
4.00–6.99
7.00–9.99
4.00–9.99
99 5.12 (4.02) 5.0 (2.0, 8.0)
102 201 3.97 (2.74) 4.54 (3.47) 4.0 (2.0, 6.0) 4.0 (2.0, 7.0)
8.01 (9.61) 4.0 (2.0, 9.0)
5.39 (4.9) 6.68 (7.68) 4.0 (2.0, 9.0) 4.0 (2.0, 9.0)
4.00–6.99
7.00–9.99
4.00–9.99
131 3.99 (3.48) 4.0 (1.0, 6.0) 0.036 5.52 (6.36) 4.0 (1.0, 7.5) 0.048
125 3.30 (3.08) 3.0 (0.0, 6.0) 0.034 4.81 (5.99) 3.0 (0.0, 7.0) 0.039
256 3.66 (3.3) 3.0 (0.0, 6.0) 0.005 5.17 (6.18) 3.0 (0.0, 7.0) 0.0056
children from 4.00 to 9.99 years showed a mean 0.88 reduction (19% reduction) in dmft scores from pre-F to post-F. Figure 1 shows the mean decayed (d), missing (m) and filled (f) components of the dmfs scores of the chil-
dren, while table 4 compares the dmfs in the pre-F and post-F children. There were significant reductions observed in mean dmfs scores from pre-F to post-F (table 4). From pre-F to post-F for 4.00- to 6.99-year-old children, the dmfs scores was reduced by 2.49. Similarly,
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
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SD = Standard deviation. * Mann-Whitney test.
Table 5. Proximal surfaces of primary molars affected by caries in children 4–9 years old in the pre-fluoridation
(pre-F) and post-fluoridation (post-F) groups Mean number of proximal surfaces with caries, n (%) per child
1st Primary molar Maxillary Mandibular Total 2nd Primary molar Maxillary Mandibular Total Total
p value*
pre-F
post-F
Mesial Distal Mesial Distal Mesial Distal
0.16 (8) 0.94 (47) 0.57 (29) 0.07 (3) 0.26 (6) 1.94 (48)
0.07 (3) 0.69 (35) 0.46 (23) 0.04 (2) 0.18 (5) 1.57 (39)
0.0082 0.0017 0.12 0.21 0.10 0.0093
Mesial Distal Mesial Distal Mesial Distal
0.1 (5) 1 (50) 0.46 (23) 0.1 (5) 1.03 (26) 0.17 (4)
0.12 (6) 0.88 (44) 0.38 (19) 0.08 (4) 0.84 (21) 0.12 (3)
0.95 0.17 0.31 0.57 0.094 0.082
Mesial Distal
1.29 (16) 2.1 (26)
1.02 (13) 1.7 (21)
0.036 0.0065
3.4 (21)
2.88 (18)
0.046
Total
Fig. 1. Mean number of decayed, missing
and filled surfaces (dmfs) per child in the pre- and post-fluoridation groups. * Comparing pre-F and post-F.
8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0
* p = 0.048 * p = 0.0056 * p = 0.039
4.00–6.99 year olds
for 7.00- to 9.99-year-old children, the dmfs scores was reduced by 0.58. Overall, in 4.00–9.99 year olds, the dmfs scores was reduced by 1.51. Table 5 shows the mean decayed, missing or filled primary molar in the proximal surfaces (dmfs) of children aged 4.00–9.99 years pre-F and post-F. Overall, there were statistically significant reductions of caries experi188
Caries Res 2015;49:184–191 DOI: 10.1159/000369864
7.00–9.99 year olds
Pre-fluoride decayed surface Pre-fluoride missing surface Pre-fluoride filled surface Post-fluoride decayed surface Post-fluoride missing surface Post-fluoride filled surface
All ages
ence for the proximal surfaces of primary molars in the post-F group when compared to the pre-F group (pre-F 21%, post-F 18%). Table 6 shows the mean number per child of primary molar occlusal surfaces that are decayed, missing or filled. Overall, the occlusal surfaces in primary molars showed an overall reduction in caries experience (pre-F 18.0%, Koh/Pukallus/Newman/Foley/Walsh/ Seow
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dmfs
* Mann-Whitney test.
Previous studies of water fluoridation on the primary dentition were largely epidemiological investigations conducted in large population groups [Armfield, 2005; Jones et al., 1997; O’Mullane et al., 1996; Saliba et al., 2008], and there are few studies that examined the preventive effects in children at high risk for caries in the primary dentition. The introduction of fluoride into the water supplies in the state of Queensland in Australia recently provided a unique opportunity to study the preventive effects of water fluoridation within a low socioeconomic community with high caries risk (LoganBeaudesert). According to an Australian national report in 2009, the dmft for 5- to 6-year-old children in Queensland is 2.52, which is approximately 18% higher than the national average of 2.13 [Ha et al., 2013]. In the district of Logan-Beaudesert, where our present study is focused, we found a pre-F dmft of 5.12 in 4- to 6-year-old children, which is double that for the state of Queensland, and consistent with the results of our previous study of this community [Newman et al., 2009]. After a mean period of 36 months of community water fluoridation in the Logan-Beaudesert area, the 4–6 year
olds experienced a mean dmft and dmfs decrease of 1.13 and 2.49, that is, one tooth or two surfaces saved per child. The reduction in dmft of 19% in the present study is smaller compared to the 31–68% reported in previous studies from other communities [Armfield, 2005, 2010; Evans et al., 2009; Jones et al., 1997; O’Mullane et al., 1996; Saliba et al., 2008]. This is likely to have resulted from the considerably longer duration of fluoridation in previous studies where the exposure times were in the range of 5 and 30 years compared to only 3 years in the present study. In addition, the extremely high caries risk of children in the Logan-Beaudesert district compared to elsewhere in Queensland and across Australia may have masked some of the benefits of water fluoridation on the teeth. The less apparent effects in the very high risk children may be due to the presence of extreme cariogenic conditions that reduced the clinical effects of the low doses of fluoride found in community water fluoridation. These conditions for cariogenic risks such as high frequency of sugar intake, lack of oral hygiene and high counts of cariogenic bacteria have been well reported in the children in this community in our previous investigations [Plonka et al., 2013a, 2013b, 2013c; Seow et al., 2009]. The present investigation employed a historical design that examined the before and after effects of water fluoridation in the same community. This design is advantageous compared to cross-sectional studies of different communities in that within the period of study in the same community, there is consistency in the factors that can affect caries rates, such as socioeconomic status, oral hygiene, dietary habits and attendance at dental clinics [Rugg-Gunn and Do, 2012]. Furthermore, variations in individual exposures to fluoride concentrations found in food and beverages (termed the ‘halo effect’) [Armfield, 2005] were also likely to be constant in the pre- and postF cohorts. Another advantage of the present study design is that the caries experience includes radiographic data based on a well-tested, sensitive and reproducible scoring system, which was developed to be consistent with the WHO clinical codes [Pitts, 1984, 1985]. The majority of previous studies on the effects of water fluoridation did not include BW radiographs and may have underestimated the caries severity as suggested previously [Gowda et al., 2009]. As demonstrated in our previous study, the use of BWs in addition to the clinical examination increased the detection of proximal surface dentinal caries in the primary dentition from 43 to 91% [Newman et al., 2009]. Although the use of BW for the present study would have improved the detection of
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
Caries Res 2015;49:184–191 DOI: 10.1159/000369864
Mean number of occlusal surfaces with caries, n (%) per child
p value*
pre-F
post-F
1st Primary molar Maxillary Mandibular Total
0.2 (10) 0.4 (20) 0.44 (11)
0.12 (6) 0.27 (14) 0.37 (9)
0.062 0.065 0.25
2nd Primary molar Maxillary Mandibular Total
0.24 (12) 0.59 (30) 0.99 (25)
0.25 (13) 0.46 (23) 0.73 (18)
0.78 0.032 0.012
Total
1.43 (18)
1.1 (14)
0.018
* Mann-Whitney test.
post-F 14%), although this is largely due to the reductions in caries experience in the mandibular second primary molar (23.0% post-F compared to 30%) (table 6).
Discussion
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Table 6. Occlusal surfaces of primary molars affected by caries in children 4–9 years old in the pre-fluoridation (pre-F) and postfluoridation (post-F) groups
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tus, and it is likely that further decreases of caries rates will be noted in the community of study with increasing time of fluoridation. It is important to note, however, that although the caries experience has been reduced since the commencement of water fluoridation, the prevalence of caries continues to be high in the community of study. The current water fluoridation program will need to continue, together with other preventive dental care programs in order to control caries in the long term.
Conclusions
Within a relatively short time frame of 36 months after the introduction of water fluoridation, there was a reduction of 19% in the caries experience of 4–9 year olds in a high risk community in the state of Queensland, Australia. The data affirm that water fluoridation provides a substantial benefit to oral health of children and reduces dental care costs for the community. Acknowledgements This paper is supported in part by the National Health and Medical Research Council of Australia (Grant No. 1046779).
Roles of Authors Designed the study: All authors. Collected the data: R.K., M.P., W.K.S. Performed the data analysis: All authors. Wrote the paper: All authors.
Disclosure Statement No conflicts of interests for any of the authors.
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Koh/Pukallus/Newman/Foley/Walsh/ Seow
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proximal caries, this effect would be similar for both preand post-fluoridation groups of children. Thus, rather than overestimating caries, the authors propose that the use of BW radiographs give a more complete estimate of the preventive effects of water fluoridation compared to results obtained from clinical assessment due to the ability to detect caries that are not visible clinically. Interestingly, in this study our BW results also demonstrated that the proximal surfaces most at risk for caries (i.e., the distal surface of the first primary molars) experienced the highest caries reduction of 26%. The present investigation, which employs a historic design, has limitations in that the factors that can influence caries rates such as socioeconomic status, diagnostic and treatment criteria and diets may have changed between the time periods. However, data from the Australian Bureau of Statistics show that in the period between 2006 and 2011 (the past two national Census dates), the indices for socioeconomic status such as relative socioeconomic disadvantage, education and occupation and economic resources for the study district have remained fairly similar within the two time periods [Australian Bureau of Statistics, 2006, 2011]. Furthermore, while approximately 39% of the population of the study district had moved address between 2006 and 2011, the mobility is largely confined to within the same district, with only 12% having moved to another part of the state of Queensland, and another 3 percent to another part of Australia [Australian Bureau of Statistics, 2006, 2011]. In addition, as there had been no change in the quality of records, caries diagnosis and treatment of caries between the pre- and post-fluoridation periods, it is highly unlikely that changes to criteria for caries diagnosis and caries treatment have led to an overestimation of caries experience in the pre-fluoridation group. Furthermore, as over 90% of children use fluoride toothpaste in both periods of time [Armfield and Beckwith, 2014; Armfield and Spencer, 2012], it is unlikely the anti-caries effect of water fluoridation has been influenced by a change in the use of fluoride toothpaste. Also, the sugar consumption frequency among children in the district has remained fairly similar in the two time periods [Koh, 2014; Seow et al., 2009], so that dietary changes are not likely to be the reason for the lower caries rates. As this district is typical of many low socioeconomic communities in Australia, with high unemployment and social disadvantage, the present results would be directly relevant to these communities. Furthermore, it is well documented that the preventive effects of water fluoridation benefit all children regardless of socioeconomic sta-
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
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Plonka KA, Pukallus ML, Barnett A, Holcombe TF, Walsh LJ, Seow WK: A controlled, longitudinal study of home visits compared to telephone contacts to prevent early childhood caries. Int J Paediatr Dent 2013a;23:23–31. Plonka KA, Pukallus ML, Barnett AG, Holcombe TF, Walsh LJ, Seow WK: A longitudinal casecontrol study of caries development from birth to 36 months. Caries Res 2013b;47:117–127. Plonka KA, Pukallus ML, Holcombe TF, Barnett AG, Walsh LJ, Seow WK: Randomized controlled trial: a randomized controlled clinical trial comparing a remineralizing paste with an antibacterial gel to prevent early childhood caries. Pediatr Dent 2013c;35:8–12. Public Health Information Development Unit Australia: Population health profile of the Logan Area Division of General Practice: supplement. Adelaide, Australia, Commonwealth of Australia, Public Health Information Development Unit, 2007. Queensland Government Statistician’s Office: Queensland Regional Profile: Logan City Local Government Area. http://statistics.oesr. qld.gov.au/qld-regional-profiles, 2014. Rugg-Gunn AJ, Do L: Effectiveness of water fluoridation in caries prevention. Community Dent Oral Epidemiol 2012;40:55–64. Saliba NA, Moimaz SA, Casotti CA, Pagliari AV: Dental caries of lifetime residents in Baixo Guandu, Brazil, fluoridated since 1953 – a brief communication. J Public Health Dent 2008;68:119–121. Seow WK, Clifford H, Battistutta D, Morawska A, Holcombe T: Case-control study of early childhood caries in Australia. Caries Res 2009;43:25–35. Slade GD, Sanders AE, Do L, Roberts-Thomson K, Spencer AJ: Effects of fluoridated drinking water on dental caries in Australian adults. J Dent Res 2013;92:376–382. Slade GD, Spencer AJ, Davies MJ, Stewart JF: Influence of exposure to fluoridated water on socioeconomic inequalities in children’s caries experience. Community Dent Oral Epidemiol 1996;24:89–100. Wenzel A: Current trends in radiographic caries imaging. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:527–539.
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Armfield JM, Spencer AJ: Dental health behaviours among children 2002–2004: the use of fluoride toothpaste, fluoride tablets and drops, and fluoride mouthrinse. Dental Statistics and Research Canberra, Australian Institute of Health and Welfare, 2012. Australian Bureau of Statistics: Census of Population and Housing: Socio-Economic Indexes for Areas (SEIFA), Australia, 2006. http:// www.abs.gov.au/AUSSTATS/abs @ .nsf/ Details Page/2033.0.55.0012006?OpenDocu ment. Australian Bureau of Statistics: Census of Population and Housing: Socio-Economic Indexes for Areas (SEIFA), Australia, 2011. http:// www.abs.gov.au/AUSSTATS/abs @ .nsf/Detai lsPage/2033.0.55.0012011?OpenDocument. Casamassimo PS, Thikkurissy S, Edelstein BL, Maiorini E: Beyond the DMFT: the human and economic cost of early childhood caries. J Am Dent Assoc 2009;140:650–657. Cobiac LJ, Vos T: Cost-effectiveness of extending the coverage of water supply fluoridation for the prevention of dental caries in Australia. Community Dent Oral Epidemiol 2012; 40: 369–376. Evans RW, Hsiau AC, Dennison PJ, Patterson A, Jalaludin B: Water fluoridation in the Blue Mountains reduces risk of tooth decay. Aust Dent J 2009;54:368–373. Fleiss JL, Levin B, Paik MC: Statistical Methods for Rates and Proportions, ed 3. Hoboken, NJ, John Wiley, 2003. Ford D, Seow WK, Kazoullis S, Holcombe T, Newman B: A controlled study of risk factors for enamel hypoplasia in the permanent dentition. Pediatr Dent 2009;31:382–388. Gowda S, Thomson WM, Foster Page LA, Croucher NA: What difference does using bitewing radiographs make to epidemiological estimates of dental caries prevalence and severity in a young adolescent population with high caries experience? Caries Res 2009;43:436–441. Ha DH, Amarasena N, Crocombe L: The dental health of Australia’s children by remoteness: child dental health survey Australia 2009; in Dental statistics and research series No. 63. Canberra, Australian Institute of Health and Welfare, 2013.
Caries Res 2015;49:184–191 DOI: 10.1159/000369864
Effects of Water Fluoridation on Caries Experience in the Primary Dentition in a High Caries Risk Community in Queensland, Australia Rongzhen Koh a Margaret L. Pukallus b Bruce Newman b Michael Foley c Laurence J. Walsh a W. Kim Seow a
a
Centre for Paediatric Dentistry, The University of Queensland School of Dentistry, Herston, b Metro South Oral Health Services, Queensland Health, Kingston, and c Metro North Oral Health Services, Queensland Health, Brisbane, Australia
Abstract Objectives: In December 2008, artificial water fluoridation was introduced for the first time to the Logan-Beaudesert district in the state of Queensland, Australia. The aim of this study was to evaluate the effects of water fluoridation in the primary dentition in this community after a period of 36 months. Methods: Children aged 4–9 years with clinical examinations and bitewing radiographs (BWs) taken before water fluoridation (pre-F) were randomly selected as comparison controls for age matched children who had been exposed to a mean period of 36 months of water fluoridation (post-F). A total of 201 sets of pre-F BWs from children (mean age 6.95 ± 1.05 years) and 256 sets of post-F BWs from children (mean age 7.19 ± 1.23 years) attending schools in the district were randomly selected. Caries experience in the primary dentition was determined as decayed, missing or filled teeth/surfaces (dmft/dmfs). Results: The caries prevalence for the pre-F group was 87% compared to 75% in the post-F group (Odds ratio (OR): 0.44, 95% CI: 0.27–0.72). Overall, there was a 19 percent reduction of mean dmft from 4.54 in the pre-F group to 3.66 in the post-F group (p = 0.005). After fluoridation, the dmfs was reduced from 6.68 to 5.17 (p = 0.0056). The distal surfaces of maxillary first primary molars
© 2015 S. Karger AG, Basel 0008–6568/15/0492–0184$39.50/0 E-Mail [email protected] www.karger.com/cre
experienced the greatest reduction (26%) in caries experience after water fluoridation (p < 0.001). Conclusions: After only 36 months of water fluoridation there was a significant drop in caries prevalence from 87 to 75% and a 19% reduction in caries experience in a community with one of the highest caries rates in Australia. © 2015 S. Karger AG, Basel
Introduction
Water fluoridation is a cost-effective and safe method of caries prevention, and has provided benefits to many communities in Australia [Armfield, 2008; Cobiac and Vos, 2012; Slade et al., 2013]. While most technologybased advances in caries prevention tend to benefit to a greater extent those who have ready access to dental services, water fluoridation indiscriminately protects an entire community regardless of socioeconomic status [Armfield, 2008]. Prior to the introduction of water fluoridation in 2008, only 5 percent of children in the state of Queensland in Australia had access to fluoridated water, compared to approximately 86 percent of the rest of the country [Armfield, 2006]. However, within two years after a large scale rollout of water fluoridation commencing in 2008, 80% of the state’s population had access to optimally fluoridated water, with an adjusted fluoride concentration between 0.6 and 0.8 mg/l. Prof. W. Kim Seow University of Queensland, Centre for Paediatric Dentistry School of Dentistry, Oral Health Centre, 288 Herston Road 4006 Herston (Australia) E-Mail k.seow @ uq.edu.au
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Key Words Water fluoridation · Caries experience · Primary dentition · Low socioeconomic
aminations in children aged 4.0–9.9 years who attended primary schools in the Logan district in the state of Queensland, Australia. The target population is considered low socioeconomic, with an unemployment rate (2013) of approximately 8% (compared with 6% for Queensland) and 31% of residents in the most disadvantaged quintile (compared with 20% in Queensland state) [Queensland Government Statistician’s Office, 2014]. The radiographs used in the study were exposed as part of the routine dental care of the children, and oral health and demographic information were obtained from existing records. All children in the study received regular dental care from the public dental clinics in the Logan-Beaudesert clinics during the period 1998 to 2013. For the pre-fluoridation (pre-F) data, a random sample of dental records of 4- to 6- and 7- to 9-year-old children who had attended routine dental treatment visits under the district’s public oral health program from 1998 to December 2008 was collected. The dental records were selected by an independent research assistant who was not part of the study. As the dental records including BWs were stored in cabinets with the children’s names by alphabetical order, the randomisation was performed by selecting the first two records from every alphabet that fitted the inclusion criteria, and repeating the process until the required numbers of children were obtained. The dental examinations and BW radiography were performed by dental clinical staff according to standard clinic policy and guidelines [Ford et al., 2009; Newman et al., 2009]. Inclusion criteria for the study were age of 4–9 years at the time of radiographic examination, and BWs of diagnostic quality. Exclusion criteria were developmental dental abnormalities such as enamel defects, and serious chronic medical conditions, such as congenital heart disease. Demographic details and oral health information collected for the study included gender, date of birth, medical history and date of BW radiographs. The post-fluoridation (post-F) data were obtained from dental examinations data and BW records of 4- to 9-year-old children from the same clinic who had the BWs and clinical data recorded at dates between January 2011 and December 2012. To standardise the diagnostic quality of the BWs, each set of radiographs was mounted on a light box and photographed with a Canon EOS-D60 SLR camera (Canon, Tokyo, Japan) with a 100 mm Canon Macro EF lens. Shutter speed was fixed at 1/90 and aperture at 5.6. The images were viewed under standardised settings in a computer using Adobe Photoshop CS software (Adobe Systems Inc., San Jose, Calif., USA).
Ethical clearance for the study was obtained from The University of Queensland School of Dentistry and Queensland Health human research ethics committees. The study assessed caries experience using the results of dental radiographs and clinical ex-
Scoring of BW Radiographs The proximal and occlusal tooth surfaces of the maxillary and mandibular primary molar teeth were scored using a modification of the scoring scale described by Pitts and applied by Morgan et al. (table 1) [Morgan et al., 2008; Pitts, 1985]. Caries experience was measured as caries present in dentine, recurrent caries or restored surfaces (table 1) [Morgan et al., 2008; Pitts, 1985]. BWs with overlapped proximal surfaces and other defects that rendered the surfaces unreadable, such as cone-cutting, were excluded from the study. All radiographs were scored blind by a single author (RK). A split screen was used to simultaneously score each radiograph and input data into a custom-designed database. To assess intra-examiner variability for caries assessment, 10 sets of BWs were scored twice, two weeks apart. The examiner’s kappa statistic score was
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
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Methods
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Before water fluoridation, 6 year-old children residing in Logan-Beaudesert, a district with one of the lowest socioeconomic status in the state of Queensland, had a mean caries experience (decayed, missing, filled teeth, dmft) index of 4.9, which is two and a half times that of the rest of Australia [Ha et al., 2013; Newman et al., 2009; Public Health Information Development Unit Australia, 2007]. The high costs of dental treatment for caries in young children place large personal and financial burdens on the children and the community [Casamassimo et al., 2009] and demonstrate the pressing need for caries prevention in this district. The effectiveness of water fluoridation for preventing dental caries has been researched extensively, with documented benefits for both primary and permanent dentitions [Rugg-Gunn and Do, 2012; Slade et al., 2013]. Previous Australian studies have reported caries reductions in the range of 10–69% in the primary dentition in children exposed to optimum water fluoridation [Rugg-Gunn and Do, 2012]. The majority of these studies, however, report on cross-sectional findings and relied on complex statistical analyses to adjust for confounding factors. Furthermore, in most studies which examined caries experience, BW radiographs were not used, which most likely led to underreporting of caries prevalence [Newman et al., 2009]. As the preventive effects of water fluoridation are thought to be the highest on smooth (proximal) surfaces, information from BWs should be added to data from the clinical examinations to ensure complete documentation of caries. In addition, there have been only a few studies that examined the preventive effects of water fluoridation on low socioeconomic children [Jones and Worthington, 1999; McLaren and Emery, 2012; Slade et al., 1996]. As early childhood caries is one of the most challenging conditions in paediatric dentistry today, it is of clinical and public health significance to determine the effects of water fluoridation on children who are most at risk to develop early childhood caries. Therefore, the aim of the present study was to evaluate the effects of water fluoridation on the caries experience of the primary dentition of 4- to 9-year-old children living in the high caries-risk, low socio-economic community of Logan-Beaudesert.
Table 1. Radiographic diagnostic scoring system and criteria for proximal caries
Score
Category
Diagnostic criteria
0
Sound
No radiolucency or restoration visible
1
Outer-half enamel lesion
Zone of increased radiolucency confined to outer half of enamel (no minimum limit)
2
Inner-half enamel lesion
Zone of increased radiolucency involving inner and outer half of enamel, including lesions extending up to but not beyond the dentinoenamel junction
3
Outer-half dentine lesion
Zone of increased radiolucency penetrating enamel and dentinoenamel junction but confined to outer half of the dentine
4
Inner-half dentine lesion
Zone of increased radiolucency penetrating into the inner half of dentine with or without pulpal involvement
5
Unreadable overlap
Unable to score surface due to overlap
6
Secondary caries
Zone of increased radiolucency associated with previously restored surface
7
Filled surface
Radiographic appearance consistent with restoration
8
Not visible
Tooth not visible on radiograph
Adapted from Morgan et al. [2008] and Pitts [1984].
Sample Size Calculations A sample size calculation found that 97 children in each of the pre- and post-fluoridation groups were required to produce an 80% power to detect a significant difference at the 0.05 level if 60% caries prevalence is reduced to 40% after the introduction of water fluoridation. To assess the caries experience, a sample size of 63 is required to have an 80% power to detect a change of dmft/dmfs from 3 pre-fluoridation to 2 after fluoridation at the 0.05 level [Fleiss et al., 2003]. Data Analysis The decayed, missing and filled teeth/surface (dmft/dmfs) index was used to assess the caries experience (table 1). A surface was classified as decayed (d) if the lesion progressed beyond the dentinoenamel junction. Carious lesions restricted to the enamel were not included [Wenzel, 1995]. The missing (m) component of primary dentition was based on guidelines set by Palmer et al. [1984], which include all missing primary molars in children aged 9 and missing primary incisors for children younger than 5 years. A molar was considered to have 5 and an incisor 4 surfaces [Palmer et al., 1984]. Missing primary incisors in children 5–7 years of age were considered to be exfoliated [Palmer et al., 1984]. The dmft/ dmfs indices were calculated from clinical records and BWs. Statistical Analysis The Mann-Whitney test was used to compare pre-F and post-F groups with respect to mean dmft and dmfs scores and the Fisher’s exact test was used to assess caries prevalence. Odds ratios and 95%
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confidence intervals were calculated using the frequency ratios to compare the pre- and post-fluoridation caries prevalence. Analyses were performed with InStat software (GraphPad Software Inc., La Jolla, Calif., USA). Significance tests were two-tailed at the 0.05 probability.
Results
Overall, a total of 201 pre-F and 256 post-F sets of BWs and dental records from 457 children were included in the study. Demographic data for the children are presented in table 2. The post-F group had been exposed to water fluoridation for a mean time period of 36.55 ± 6.53 months before the BWs were taken. The mean age ± SD of pre-F and post-F children was 6.95 ± 1.05 and 7.19 ± 1.23 years respectively (table 2). Table 3 shows the caries prevalence of the pre-F and post-F children. As shown in table 3, the pre-F group, 175 (87%) of the children showed caries experience (dmft >0) compared to 191 (75%) in the post-F group The odds for post-F children to experience decayed, missing or filled teeth were significantly lower than the pre-F children (OR = 0.44, 95% CI: 0.27–0.72). Table 4 shows the mean dmft scores of primary and permanent teeth in pre-F and post-F children. The mean total post-F dmft scores of the 4.00–6.99 and 7.00–9.99 year old children represented reductions of 22 and 17% compared to the respective pre-F mean scores. Overall, Koh/Pukallus/Newman/Foley/Walsh/ Seow
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0.91 for intra-examiner consistency, indicating excellent agreement. Inter-examiner variability was tested between the first and last author (WKS), a specialist paediatric dentist, using 20 sets of BWs, and yielded a kappa statistic score of 0.89, indicating high inter-examiner consistency.
Table 2. Mean ages of children and exposure time periods to water fluoridation
Age, years 4.00–6.99 Pre-F Post-F 7.00–9.99 Pre-F Post-F Total (4.00–9.99) Pre-F Post-F
n
Mean age, years (±SD)
Mean period of time exposed to water fluoridation, months (±SD)
99 131
6.07±0.56 6.18±0.61
36.21±6.37
102 125
7.81±0.63 8.25±0.73
36.87±6.69
201 256
6.95±1.05 7.19±1.23
36.55±6.53
SD = Standard deviation; Pre-F = pre-fluoridation; Post-F = post-fluoridation.
Table 3. Prevalence of children with dmft greater than zero in the pre- and post-fluoridation groups
Age, years
4.00–6.99 7.00–9.99 Total (4.00–9.99)
Pre-fluoridation
Post-fluoridation
n
caries affected, n (%)
n
caries affected, n (%)
99 102 201
83 (84) 92 (90) 175 (87)
131 125 256
99 (76) 92 (74) 191 (75)
p value*
Odds ratio post-F/pre-F (95% CI)
0.14 0.0019 0.0009
0.60 (0.31–1.16) 0.30 (0.14–0.65) 0.44 (0.27–0.72)
* Fisher’s exact test. CI = Confidence interval.
Table 4. Caries experience (mean number of decayed, missing and filled teeth/surface) (dmft/dmfs) in the pre-fluoridation (pre-F) group
and post-fluoridation (post-F) groups of children Pre-F, age (years)
n Mean dmft (±SD) Median dmft (Q1, Q3) p value comparing post-F and pre-F dmft* Mean dmfs (±SD) Median dmfs (Q1, Q3) p value comparing post-F and pre-F dmfs*
Post-F, age (years)
4.00–6.99
7.00–9.99
4.00–9.99
99 5.12 (4.02) 5.0 (2.0, 8.0)
102 201 3.97 (2.74) 4.54 (3.47) 4.0 (2.0, 6.0) 4.0 (2.0, 7.0)
8.01 (9.61) 4.0 (2.0, 9.0)
5.39 (4.9) 6.68 (7.68) 4.0 (2.0, 9.0) 4.0 (2.0, 9.0)
4.00–6.99
7.00–9.99
4.00–9.99
131 3.99 (3.48) 4.0 (1.0, 6.0) 0.036 5.52 (6.36) 4.0 (1.0, 7.5) 0.048
125 3.30 (3.08) 3.0 (0.0, 6.0) 0.034 4.81 (5.99) 3.0 (0.0, 7.0) 0.039
256 3.66 (3.3) 3.0 (0.0, 6.0) 0.005 5.17 (6.18) 3.0 (0.0, 7.0) 0.0056
children from 4.00 to 9.99 years showed a mean 0.88 reduction (19% reduction) in dmft scores from pre-F to post-F. Figure 1 shows the mean decayed (d), missing (m) and filled (f) components of the dmfs scores of the chil-
dren, while table 4 compares the dmfs in the pre-F and post-F children. There were significant reductions observed in mean dmfs scores from pre-F to post-F (table 4). From pre-F to post-F for 4.00- to 6.99-year-old children, the dmfs scores was reduced by 2.49. Similarly,
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
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SD = Standard deviation. * Mann-Whitney test.
Table 5. Proximal surfaces of primary molars affected by caries in children 4–9 years old in the pre-fluoridation
(pre-F) and post-fluoridation (post-F) groups Mean number of proximal surfaces with caries, n (%) per child
1st Primary molar Maxillary Mandibular Total 2nd Primary molar Maxillary Mandibular Total Total
p value*
pre-F
post-F
Mesial Distal Mesial Distal Mesial Distal
0.16 (8) 0.94 (47) 0.57 (29) 0.07 (3) 0.26 (6) 1.94 (48)
0.07 (3) 0.69 (35) 0.46 (23) 0.04 (2) 0.18 (5) 1.57 (39)
0.0082 0.0017 0.12 0.21 0.10 0.0093
Mesial Distal Mesial Distal Mesial Distal
0.1 (5) 1 (50) 0.46 (23) 0.1 (5) 1.03 (26) 0.17 (4)
0.12 (6) 0.88 (44) 0.38 (19) 0.08 (4) 0.84 (21) 0.12 (3)
0.95 0.17 0.31 0.57 0.094 0.082
Mesial Distal
1.29 (16) 2.1 (26)
1.02 (13) 1.7 (21)
0.036 0.0065
3.4 (21)
2.88 (18)
0.046
Total
Fig. 1. Mean number of decayed, missing
and filled surfaces (dmfs) per child in the pre- and post-fluoridation groups. * Comparing pre-F and post-F.
8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0
* p = 0.048 * p = 0.0056 * p = 0.039
4.00–6.99 year olds
for 7.00- to 9.99-year-old children, the dmfs scores was reduced by 0.58. Overall, in 4.00–9.99 year olds, the dmfs scores was reduced by 1.51. Table 5 shows the mean decayed, missing or filled primary molar in the proximal surfaces (dmfs) of children aged 4.00–9.99 years pre-F and post-F. Overall, there were statistically significant reductions of caries experi188
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7.00–9.99 year olds
Pre-fluoride decayed surface Pre-fluoride missing surface Pre-fluoride filled surface Post-fluoride decayed surface Post-fluoride missing surface Post-fluoride filled surface
All ages
ence for the proximal surfaces of primary molars in the post-F group when compared to the pre-F group (pre-F 21%, post-F 18%). Table 6 shows the mean number per child of primary molar occlusal surfaces that are decayed, missing or filled. Overall, the occlusal surfaces in primary molars showed an overall reduction in caries experience (pre-F 18.0%, Koh/Pukallus/Newman/Foley/Walsh/ Seow
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dmfs
* Mann-Whitney test.
Previous studies of water fluoridation on the primary dentition were largely epidemiological investigations conducted in large population groups [Armfield, 2005; Jones et al., 1997; O’Mullane et al., 1996; Saliba et al., 2008], and there are few studies that examined the preventive effects in children at high risk for caries in the primary dentition. The introduction of fluoride into the water supplies in the state of Queensland in Australia recently provided a unique opportunity to study the preventive effects of water fluoridation within a low socioeconomic community with high caries risk (LoganBeaudesert). According to an Australian national report in 2009, the dmft for 5- to 6-year-old children in Queensland is 2.52, which is approximately 18% higher than the national average of 2.13 [Ha et al., 2013]. In the district of Logan-Beaudesert, where our present study is focused, we found a pre-F dmft of 5.12 in 4- to 6-year-old children, which is double that for the state of Queensland, and consistent with the results of our previous study of this community [Newman et al., 2009]. After a mean period of 36 months of community water fluoridation in the Logan-Beaudesert area, the 4–6 year
olds experienced a mean dmft and dmfs decrease of 1.13 and 2.49, that is, one tooth or two surfaces saved per child. The reduction in dmft of 19% in the present study is smaller compared to the 31–68% reported in previous studies from other communities [Armfield, 2005, 2010; Evans et al., 2009; Jones et al., 1997; O’Mullane et al., 1996; Saliba et al., 2008]. This is likely to have resulted from the considerably longer duration of fluoridation in previous studies where the exposure times were in the range of 5 and 30 years compared to only 3 years in the present study. In addition, the extremely high caries risk of children in the Logan-Beaudesert district compared to elsewhere in Queensland and across Australia may have masked some of the benefits of water fluoridation on the teeth. The less apparent effects in the very high risk children may be due to the presence of extreme cariogenic conditions that reduced the clinical effects of the low doses of fluoride found in community water fluoridation. These conditions for cariogenic risks such as high frequency of sugar intake, lack of oral hygiene and high counts of cariogenic bacteria have been well reported in the children in this community in our previous investigations [Plonka et al., 2013a, 2013b, 2013c; Seow et al., 2009]. The present investigation employed a historical design that examined the before and after effects of water fluoridation in the same community. This design is advantageous compared to cross-sectional studies of different communities in that within the period of study in the same community, there is consistency in the factors that can affect caries rates, such as socioeconomic status, oral hygiene, dietary habits and attendance at dental clinics [Rugg-Gunn and Do, 2012]. Furthermore, variations in individual exposures to fluoride concentrations found in food and beverages (termed the ‘halo effect’) [Armfield, 2005] were also likely to be constant in the pre- and postF cohorts. Another advantage of the present study design is that the caries experience includes radiographic data based on a well-tested, sensitive and reproducible scoring system, which was developed to be consistent with the WHO clinical codes [Pitts, 1984, 1985]. The majority of previous studies on the effects of water fluoridation did not include BW radiographs and may have underestimated the caries severity as suggested previously [Gowda et al., 2009]. As demonstrated in our previous study, the use of BWs in addition to the clinical examination increased the detection of proximal surface dentinal caries in the primary dentition from 43 to 91% [Newman et al., 2009]. Although the use of BW for the present study would have improved the detection of
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
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Mean number of occlusal surfaces with caries, n (%) per child
p value*
pre-F
post-F
1st Primary molar Maxillary Mandibular Total
0.2 (10) 0.4 (20) 0.44 (11)
0.12 (6) 0.27 (14) 0.37 (9)
0.062 0.065 0.25
2nd Primary molar Maxillary Mandibular Total
0.24 (12) 0.59 (30) 0.99 (25)
0.25 (13) 0.46 (23) 0.73 (18)
0.78 0.032 0.012
Total
1.43 (18)
1.1 (14)
0.018
* Mann-Whitney test.
post-F 14%), although this is largely due to the reductions in caries experience in the mandibular second primary molar (23.0% post-F compared to 30%) (table 6).
Discussion
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Table 6. Occlusal surfaces of primary molars affected by caries in children 4–9 years old in the pre-fluoridation (pre-F) and postfluoridation (post-F) groups
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tus, and it is likely that further decreases of caries rates will be noted in the community of study with increasing time of fluoridation. It is important to note, however, that although the caries experience has been reduced since the commencement of water fluoridation, the prevalence of caries continues to be high in the community of study. The current water fluoridation program will need to continue, together with other preventive dental care programs in order to control caries in the long term.
Conclusions
Within a relatively short time frame of 36 months after the introduction of water fluoridation, there was a reduction of 19% in the caries experience of 4–9 year olds in a high risk community in the state of Queensland, Australia. The data affirm that water fluoridation provides a substantial benefit to oral health of children and reduces dental care costs for the community. Acknowledgements This paper is supported in part by the National Health and Medical Research Council of Australia (Grant No. 1046779).
Roles of Authors Designed the study: All authors. Collected the data: R.K., M.P., W.K.S. Performed the data analysis: All authors. Wrote the paper: All authors.
Disclosure Statement No conflicts of interests for any of the authors.
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proximal caries, this effect would be similar for both preand post-fluoridation groups of children. Thus, rather than overestimating caries, the authors propose that the use of BW radiographs give a more complete estimate of the preventive effects of water fluoridation compared to results obtained from clinical assessment due to the ability to detect caries that are not visible clinically. Interestingly, in this study our BW results also demonstrated that the proximal surfaces most at risk for caries (i.e., the distal surface of the first primary molars) experienced the highest caries reduction of 26%. The present investigation, which employs a historic design, has limitations in that the factors that can influence caries rates such as socioeconomic status, diagnostic and treatment criteria and diets may have changed between the time periods. However, data from the Australian Bureau of Statistics show that in the period between 2006 and 2011 (the past two national Census dates), the indices for socioeconomic status such as relative socioeconomic disadvantage, education and occupation and economic resources for the study district have remained fairly similar within the two time periods [Australian Bureau of Statistics, 2006, 2011]. Furthermore, while approximately 39% of the population of the study district had moved address between 2006 and 2011, the mobility is largely confined to within the same district, with only 12% having moved to another part of the state of Queensland, and another 3 percent to another part of Australia [Australian Bureau of Statistics, 2006, 2011]. In addition, as there had been no change in the quality of records, caries diagnosis and treatment of caries between the pre- and post-fluoridation periods, it is highly unlikely that changes to criteria for caries diagnosis and caries treatment have led to an overestimation of caries experience in the pre-fluoridation group. Furthermore, as over 90% of children use fluoride toothpaste in both periods of time [Armfield and Beckwith, 2014; Armfield and Spencer, 2012], it is unlikely the anti-caries effect of water fluoridation has been influenced by a change in the use of fluoride toothpaste. Also, the sugar consumption frequency among children in the district has remained fairly similar in the two time periods [Koh, 2014; Seow et al., 2009], so that dietary changes are not likely to be the reason for the lower caries rates. As this district is typical of many low socioeconomic communities in Australia, with high unemployment and social disadvantage, the present results would be directly relevant to these communities. Furthermore, it is well documented that the preventive effects of water fluoridation benefit all children regardless of socioeconomic sta-
Reduction in Caries Experience of 4–9 Year-Olds after Water Fluoridation
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Caries Res 2015;49:184–191 DOI: 10.1159/000369864
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