Fluoride and Oral Health.

The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.

Is tooth wear in the primary dentition predictive of tooth wear in the permanent dentition? Report from a longitudinal study.

OBJECTIVES: To determine the prevalence of tooth wear in the permanent dentition of a sample of 12-year-old school children and establish whether an association exists between tooth wear recorded now and tooth wear recorded in their primary dentition at age five. DESIGN: A prospective cohort study. METHODS: At follow-up to a previous study complete data were available for 123 children; fieldwork was conducted in the child's primary school. Measurement of tooth wear used a scoring system modified from the Smith and Knight Tooth Wear Index (TWI). Tooth wear which had progressed to dentine was assessed on the occlusal surfaces of the four first permanent molars, the labial, lingual/palatal and incisal surfaces of the six upper and six lower anterior teeth; a total of 40 scoreable surfaces. Demographic data were collected from the parents, and a questionnaire on oral hygiene habits, diet and behaviours was completed by each child. RESULTS: In total 38% (n = 47) of subjects had tooth wear, if incisor teeth only were included, 33% (n = 40) had tooth wear and similarly if the occlusal surfaces of molar teeth only were included 10% (n = 12) had signs of tooth wear. Gender was significantly associated with tooth wear: males had more tooth wear. The presence of tooth wear with dentine exposed in the primary dentition was significantly associated with tooth wear on the occlusal surfaces of the first permanent molars. CONCLUSION: Males had more tooth wear than females. An association existed between tooth wear recorded at age 5 and molar tooth wear recorded at age 12. Tooth wear is a lifelong cumulative process and should be recorded in both the primary and permanent dentitions.

Primary tooth fluorosis in 5-year-old schoolchildren in Ireland.

AIM: This was to determine the prevalence of primary tooth fluorosis in the dentitions of 5-year-old schoolchildren. A subsidiary aim was to investigate whether an association existed between the presence of primary tooth fluorosis, fluoridation status, infant feeding practices or the oral hygiene practices of the child. STUDY DESIGN: A cross-sectional and stratified by fluoridation status study. METHODS: Fluorosis was recorded using a modification of the Tooth Surface Index of Fluorosis (TSIF). Demographic data, information on infant feeding practices and oral hygiene practices were collected via a parental questionnaire. STATISTICS: Stepwise logistic regression analysis. RESULTS: Fluorosis prevalence in the fluoridated group (n=208) was 32%; 29.3% (n=61) had a modified TSIF score of 1; 2.4% (n=5) had a modified TSIF score of 2; and 1% (n=1) had a modified TSIF score of 5. In the non-fluoridated group (n=86) one child had a modified TSIF score of 1. Primary tooth prevalence of fluorosis in the entire sample (n=294) was 23%. Factors that were associated with primary tooth fluorosis were: fluoridation status (p= 0.0003, 95% CI = 5-281) and the age at which toothbrushing with toothpaste commenced (p = 0.016, 95% C.I. 1.1 - 3.8). No association with infant feeding practices was identified. CONCLUSION: The overall prevalence of primary tooth fluorosis was 23%. Lifetime residence in a fluoridated area and commencement of toothbrushing with toothpaste between 12 and 18 months of age were associated with primary tooth fluorosis. No association with infant feeding practices was identified.

The future of water fluoridation.

Recently, questions have been raised about the possible reduced effectiveness and cost-effectiveness of water fluoridation in the prevention of dental caries in developed countries. The increase in environmental fluorides since water fluoridation was first introduced in 1945 (particularly from fluoride toothpastes, mouthrinses, and from foods and drinks) generally provided the basis for these questions. A related phenomenon which might decrease the efficiency of water fluoridation is the reduced caries levels in many developed countries. It has also been suggested that excessive fluoride intake, especially in fluoridated communities where there is widespread use of fluoride toothpastes, is likely to manifest itself in an increased dental fluorosis prevalence. In this paper, recent data from Ireland which are similar to those recorded in many developed countries are used to answer these questions in part. It is concluded that water fluoridation continues to be an effective and cost-effective strategy for caries prevention in areas where the overall caries level has declined and where the cost of water fluoridation implementation has increased. Also, there is no evidence of excessive fluoride intake in fluoridated communities where fluoride toothpastes are widely used.

Use of sequential analysis in clinical trials of caries prophylactic agents.

Using a sequential t test, the objectives of two 3-year experimental clinical trials were achieved more efficiently by using fewer subjects over a shorter time. The assumption of identical distributions of each batch of data analyzed was not apparent and further work to establish the robustness of sequential t tests is indicated. Identification of subjects with more consistent caries increments during the period of a trial would also help to satisfy this assumption.

A re-analysis of a caries clinical trial by survival analysis.

The decline in caries prevalence, the increases in the level of fluoride exposure, and the lack of placebo control subjects have complicated caries clinical trials in recent times. There has been a substantial increase in the numbers of subjects required for the detection of statistically significant differences between dental products, and hence, the cost of these trials has grown enormously. This study uses a new statistical approach to the analysis of the data from these trials with the ultimate aim of providing a more sensitive method of analysis. The new approach uses survival analysis, where the outcome measure is the survival time of an individual tooth surface. It exploits recent developments in the analysis of clustered survival data where survival times within the same cluster or subject are correlated. To illustrate, the new method of analysis was used for the North Wales, UK, caries clinical trial. It is concluded that survival analysis uses most of the data available in a caries clinical trial, an outcome measure that is easily understood and may lead to a more sensitive method of analysis.

A three-year clinical trial of a combination of trimetaphosphate and sodium fluoride in silica toothpastes.

The relative efficacy of NaF silica toothpastes containing 1000 ppm fluoride and 1500 ppm fluoride in the control of dental caries is not clear-cut. Also, it has not been established that incorporation of trimetaphosphate (TMP) improves the anticaries activity of NaF toothpastes. A three-year clinical trial was conducted to test the hypotheses that: (i) the anticaries activity of NaF toothpastes containing 1500 ppm F was greater than that of NaF toothpastes containing 1000 ppm F, and (ii) inclusion of TMP improved the efficacy of NaF silica pastes. Subsidiary aims included determination of whether frequency of toothbrushing and method of rinsing after brushing were correlated with caries increments. The study involved 4196 children aged 11 to 12 years at outset. These participants had been selected from a pool of 7374 potential subjects on the basis of caries experience and dental eruption pattern. They were stratified by sex, examiner, and presence of calculus and caries, and were allocated at random to one of the four toothpastes under study. Using mirror and probe and also FOTI, we carried out clinical examinations at baseline and annually thereafter for 3 yrs. Bitewing radiographs of a subset of children were taken at baseline and at the end of the study. The outcome measure for the study, DMFS increment, was defined as the increase in caries over 3 yrs, taking into account changes occurring on individual tooth surfaces. Data for 3467 subjects were available for analyses at both baseline and year 3 examinations. Radiographs were taken for 1942 subjects at both baseline and year 3 examinations. The mean three-year clinical-only DMFS increment for the subjects using 1500-ppm-NaF pastes was 3.93, which was 6% lower than the corresponding mean of 4.19 for the 1000-ppm-NaF pastes. There was no significant difference between the mean DMFS increment for those using paste with or without TMP. Subjects who claimed to brush more frequently or who claimed not to use a tumbler to rinse after toothbrushing had lower three-year DFMS increments.

A 12-month study of the efficacy of a pre-brushing rinse in plaque removal.

A 12-month clinical trial was conducted to compare the effectiveness of a pre-brushing rinse (PBR) in plaque removal with that of water. Four groups participated in the study; group 1 (test group) rinsed with PBR before brushing; group 2 rinsed with plain tap water; group 3 brushed only; and group 4 rinsed with sterile water (same color as the PBR). Pre-brushing and post-brushing plaque scores were recorded at baseline, 3 months, 6 months, 9 months (Ramjford surfaces) and 12 months for groups 1, 2, and 3 and at baseline, 3 months and 6 months for group 4. Pre-brushing minus post-brushing plaque scores (decrements) were significantly higher in the PBR group at baseline, and 6, 9, and 12 months. Using a single criterion (gingival bleeding index) there were no differences between the 4 groups at any of the 5 assessments, hence, the clinical significance of the higher plaque removal scores in the PBR group remains in doubt.

Variation of salivary flow rate in adolescents.

Forty-three children living in North Wales, an area with a temperate climate, were involved in this study from September 1990 until June 1991 inclusive. By standardizing the method and timing of collection the effect of external factors on the salivary flow rate was minimized. Flow rate was assessed once a month. Of the original group of 43, 18 attended at each occasion; these were termed the "regular attendees". Repeated-measures analysis of variance indicated that unstimulated salivary flow rate varied within an individual over time in both the total (43, p < 0.001) and the regular groups (18, p < 0.001). This relation remained when the initial September and October measurements were excluded (p < 0.05, n = 43). When the subgroup, the regular attendees (n = 18), was considered, this relation almost reached statistical significance when September was excluded (p = 0.052) and when both months were omitted the association was no longer evident (p = 0.094). Similar to previously published results from a study of individuals in a subtropical climate, salivary flow-rate variation was inversely associated with ambient temperature in both the total (n = 43) and the subsection of regular attendees (n = 18) (p < 0.05).

Efficiency in clinical trials of caries preventive agents and methods.

The idea sequence of tests required to establish a caries prophylactic agent or procedure on a public health basis is described and a clear distinction is drawn between an experimental clinical trial, carried out under ideal conditions, and a community clinical trial carried out under real life conditions. Because of the artificial nature of an experimental clinical trial there are strict limitations placed on its objectives and the inferences that can be drawn from its results. Bearing these limitations in mind and using the data collected during a 3-year trial of a fluoride mouthrinse, two methods of improving the efficiency of experimental clinical trials of caries prophylactic agents are considered. Firstly, a reduction in length is suggested either by planning the trial to run for a shorter period in the first place or, alternatively, by stopping the trial when the criteria for success have been satisfied. Secondly, it is proposed that the number of subjects participating in the trial be reduced by excluding those whose contributions to the aims of the trial are likely to be low.

Dental treatment needs in three institutions for the handicapped.

Treatment needs for caries, periodontal disease and dentures were assessed in 194 handicapped persons attending three institutions for the handicapped in Cork, Ireland. Criteria and methods of assessment used were those employed in the recently completed National Survey of Childrens' Dental Health in Ireland, which were based on (WHO) Oral Health Surveys--Basic Methods. The need for extractions and complicated restorations was highest in older patients, whilst the removal of sub- and supragingival calculus was the most common periodontal treatment need. Treatment was completed for 130 patients by final year dental undergraduates or junior hospital staff (primary care), while the remaining 64 were treated by consultant staff (secondary care).

Identification of areas with high levels of untreated dental caries.

In order to examine the geographical variation of dental health within 10 county districts in North Wales, 3538 children were examined. The associations between three demographic indicators, based on the 1981 OPCS census, and dental health outcomes were assessed for electoral wards within the county districts. The Townsend and Jarman indices were the first two indicators employed and the third was based on a mathematical model representing the variation in the mean number of untreated decayed surfaces per person for the wards. This model was developed using the children examined in the five most westerly county districts. Using the data derived from the five most easterly county districts, the three indicators were assessed. All three showed strong correlations (r > or = 0.88) with dental health. These results indicate that measures of dental health based on large administrative units may obscure variation within them. It is concluded that geographical methods of this type may be useful for targeting dental resources at small areas with high levels of need.

Covariance analysis (for comparison of caries increments) in clinical trials of caries-prophylactic agents.

The validity of the assumptions of linearity, parallelism and homogeneity underlying the use of covariance analysis were tested using data from two 3-year clinical trials of caries-prophylactic agents in which over 900 children aged 11-12 years participated. Three covariables were used; initial DMFS (IDMFS), initial surfaces at risk (ISAR) and IDMFS X ISAR/IDMFS + ISAR. For all three covariables the assumptions of linearity and parallelism could not be rejected. However, wide departures from the assumption of homogeneity were found, and it was concluded that analysis of covariance was not appropriate for comparing the caries increments investigated.

The distribution of dentists and the uptake of dental treatment by schoolchildren in England.

The uptake of treatment by 508 14-year-old children in different social classes in two towns in England with different dentist:population ratios was investigated. In the town with the unfavorable dentist:population ratio (Town U) the uptake of treatment was considerably higher in the higher social classes. In the town with the favorable dentist:population ratio (Town F) the uptake was similar throughout the social scale. The results suggest that the availability of dentists rather than sociologic attitudes to dental health is largely responsible for the differential uptake of treatment by children in the different social classes.

Edentulousness in the United Kingdom and Ireland.

Surveys of adult (16 yr and over) dental health were conducted in England/Wales and Scotland (n = 5967) and in Ireland (n = 1764) and Northern Ireland (n = 1176) in 1979. From the results of these surveys a comparison is made between levels of edentulousness, attendance patterns, attitude to loss of teeth and the wearing of full dentures. Scotland had the highest level of edentulousness (39%) and Ireland the lowest (26%). England/Wales had a level of 29% and Northern Ireland 33%. The percentage edentulous increased considerably ith age and females had a higher level of edentulousness than males. Regular attendance at the dentist was lowest in Ireland and in all countries there was a greater preference for filling rather than extraction of teeth. Levels of edentulousness do not appear to be directly related to any of the parameters investigated.

Prevalence of enamel defects/fluorosis in fluoridated and non-fluoridated areas in Ireland.

Water fluoridation was introduced in Ireland in 1964 and in recent years the availability of fluoride from other sources had increased. As part of a National Survey of Children's Health in Ireland Dean's and the DDE indices were used to determine the prevalence of enamel fluorosis/defects in 8- and 15-yr-old children in fluoridated and non-fluoridated areas. Over 94% of the children examined in all areas were regarded as having normal enamel, as defined by Dean's index, the remainder showing evidence of either questionable, very mild or mild fluorosis. Between 52% and 63% of the children had one or more teeth affected by enamel defects when measured by the DDE index. The prevalence of enamel fluorosis/defects was similar in children living in fluoridated and non-fluoridated areas but the prevalence of diffuse opacities (DDE) was higher in the fluoridated areas.

Caries prevalence and treatment need amongst children in an Arabian community.

A total of 1400 Saudi Arabian children in age groups 6-12 and 15 yr in private and public schools were examined for dental caries and treatment need in the cities of Jeddah (less than 0.30 ppm fluoride in drinking water), Rabagh (0.77 ppm F-) and Mecca (2.47 ppm F-). The mean dmft in 6-yr-olds in private schools in Jeddah was 2.9 compared with 6.3 in public schools (P less than 0.001). The d component accounted for 65% of the total dmft in private schools and 76% in public schools in Jeddah. The mean dmft values in private and public schools in Rabagh were 1.5 and 2.8 respectively and 2.7 and 2.8 in Mecca; the d component accounted for approximately 65% in all groups. The figures for permanent teeth in 12- and 15-yr-olds show similar trends with caries levels being the highest in public schools in Jeddah; approximately 60% of the total DMFT was attributable to the D component in both school types in all three cities. Most of the treatment required in all three cities comprised one- or two-surface fillings. The need for treatment was significantly higher in public schools.

The demographic and social variation in the prevalence of dental enamel opacities in north Wales.

The variation in the prevalence of developmental defects of enamel in areas of North Wales with low levels of fluoride in the drinking water was studied. Significant differences in the prevalence of diffuse opacities were found for the ten county districts in the study area. In addition, there was an association between area deprivation, as measured using the Townsend index, and diffuse opacity prevalence. The prevalence of subjects with one or more diffuse opacities was lower in more deprived electoral wards than those less deprived. For demarcated opacities and hypoplastic defects in the ten county districts, the prevalences were not significantly different and there was no association with area deprivation.

The association between area deprivation and dental caries in groups with and without fluoride in their drinking water.

In order to determine the association between social background and dental caries for subjects living in areas with and without fluoride in the drinking water, lifetime residents from Anglesey (0.7 mg/l F-, n = 196) and Chester/Bala (< 0.1 mg/l F-, n = 267) were examined. The mean age overall was 14.1 (+/- 0.3) years. For the Anglesey group, when differences in material deprivation were controlled, the mean DMFS was 2.9 compared with 4.3 in Chester/Bala, a difference of 33 per cent. Using multiple linear regression it was found that there was no interaction between material deprivation and water fluoridation. This suggested that absolute differences in dental caries between these areas with and without fluoride in the drinking water were similar for different strata of deprivation. It follows that percentage reductions in dental caries resulting from fluoridation of water supplies tended to be less in deprived than non deprived groups.

Factors affecting caries levels amongst 5-year-old children in County Kerry, Ireland.

OBJECTIVE: To investigate the factors associated with high caries levels in 5-year-old children in the Kerry Community Care Area of the Southern Health Board in Ireland. DESIGN: Cross-sectional study. SETTING: County Kerry, Ireland in 1997. SUBJECTS: A random sample of 5-year-old children. METHOD: Six hundred and thirty-six 5-year-old children were examined for caries following WHO diagnostic criteria. Information on possible caries risk factors was collected by means of a parental questionnaire. RESULTS: Using multivariate logistic regression analysis the variables most significantly associated with the presence of caries were water fluoridation status, whether or not the child took the baby feeding bottle to bed, the age at which tooth brushing started and the number of sweet snacks and drinks taken in a day. While there was a wide variation in caries levels between nine geographic areas in Co. Kerry the only significant geographic variation found was between fluoridated and non-fluoridated areas. CONCLUSION: The prevalence of dental caries amongst 5-year-old children in Co. Kerry was highest in those residing in non-fluoridated communities, in those who took a baby feeding bottle to bed, in those who did not commence tooth brushing until after two years of age and in those who had sweet snacks or sweet drinks between meals three or more times per day.