The limitations of a 'high-risk' approach for the prevention of dental caries

Dental caries

Dental caries, otherwise known as tooth decay, is one of the most prevalent chronic diseases of people worldwide; individuals are susceptible to this disease throughout their lifetime. Dental caries forms through a complex interaction over time between acid-producing bacteria and fermentable carbohydrate, and many host factors including teeth and saliva. The disease develops in both the crowns and roots of teeth, and it can arise in early childhood as an aggressive tooth decay that affects the primary teeth of infants and toddlers. Risk for caries includes physical, biological, environmental, behavioural, and lifestyle-related factors such as high numbers of cariogenic bacteria, inadequate salivary flow, insufficient fluoride exposure, poor oral hygiene, inappropriate methods of feeding infants, and poverty. The approach to primary prevention should be based on common risk factors. Secondary prevention and treatment should focus on management of the caries process over time for individual patients, with a minimally invasive, tissue-preserving approach.

Slow-release fluoride devices for the control of dental decay

BACKGROUND

Slow-release fluoride devices have been investigated as a potentially cost-effective method of reducing dental caries in those with high risk of disease.

OBJECTIVES

To evaluate the effectiveness of different types of slow-release fluoride devices on preventing, arresting, or reversing the progression of carious lesions on all surface types of deciduous and permanent teeth.

SEARCH STRATEGY

We searched (up until February 2005) multiple electronic databases (Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, EMBASE), bibliographic references of identified randomised controlled trials (RCTs), textbooks, review articles, and meta-analyses. Letters were sent to authors of identified RCTs asking for clarifications and unpublished or ongoing research. Relevant journals were handsearched for more recent reports than those obtained from databases.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials (RCTs) comparing slow-release fluoride devices with an alternative fluoride treatment, placebo, or no intervention in all age groups. The main outcomes measures sought were changes in numbers of decayed, missing, and filled teeth or surfaces (DMFT/DMFS in permanent teeth or dmft/dmfs in primary teeth) and progression of carious lesions through enamel and into dentine.

DATA COLLECTION AND ANALYSIS

Abstracts of all reports identified were considered independently by two review authors and full reports obtained of any potentially relevant articles to allow further assessment for relevance and validity. Data extraction and quality assessment were conducted independently by two and three review authors respectively, with arbitration by the fourth. Where uncertainty existed, authors were contacted for additional information.

MAIN RESULTS

Only one trial involving 174 children fully met the criteria for inclusion in this review. Although 132 children were still included in the trial at the 2-year completion point, examination and statistical analysis was performed on only the 63 children who had retained the beads. Thirty-one of these were in the intervention group and 32 in the control group. Amongst these 63 children, caries increment was reported to be statistically significantly lower in the intervention group than in the placebo group (mean difference: -0.72 DMFT, 95% confidence interval -1.23 to -0.21 and -1.52 DMFS, 95% confidence interval -2.68 to -0.36)

AUTHORS' CONCLUSIONS

There is some evidence of a caries-inhibiting effect of slow-release fluoride glass beads. This evidence is regarded as weak and unreliable because the results were from participants selected on the basis of bead retention rather than an intention-to-treat analysis.

The 80-20 phenomenon (80:20 distribution of caries) — Myth or Fact

For the past decade the phrase '80% of caries experience is found in 20% of the population' has been repeated so frequently, including by respected academics, that it has become accepted as fact by many in the dental profession. But is it a true representation of the state of dental health in the UK population, or an unsubstantiated convenient statement? Epidemiological data do not support the assertion.

The distribution of burden of dental caries in schoolchildren: a critique of the high-risk caries prevention strategy for populations

BACKGROUND

The 'high-risk approach' is a commonly adopted strategy recommended for the prevention of dental caries in populations. The scientific basis for the strategy has been questioned. The objective of this study is to assess the contribution that children identified at 'high-risk' made towards the total of new caries lesions over a 4-year period, by analysing the distribution of new lesions per 100 children.

METHODS

Data are from the National Preventive Dentistry Demonstration Programme (NPDDP) in the United States. The analyses identified the distribution of new carious lesions over a 4-year period in four groups of 7 year-old children who received differing preventive regimes.

RESULTS

The majority of new lesions occurred in those children classified at lowest caries risk at baseline. Irrespective of the preventive regime adopted and the initial caries levels, children classified as 'highest risk' contributed less than 6% of the total number of new lesions developing over 4 years.

CONCLUSION

These findings challenge the basis for the adoption of a high-risk strategy.

Caries preventive methods in child dental care reported by dental hygienists, Norway, 1995 and 2004

Dental hygienists are used as first-line personnel in child dental care in Norway, and have an increasing influence on the delivery of preventive dental services. The purpose of this study was to describe: (1) preventive methods reported by hygienists in child dental care in Norway and (2) changes in preventive care during the 9-year period 1995 to 2004. Questionnaires were sent to all dental hygienists in the public dental services in Norway in 1995 and 2004; 70% (199 of 286) were returned in 1995 and 71% (210 of 297) in 2004. The hygienists considered one-third of children to be at risk of caries and spent 45 min of preventive care on these children every 16th month, while the remaining children were given 15 min of prevention every 20th month. One-third of the hygienists provided fluoride varnish for all children and one-fourth placed sealants routinely. Ninety percent of the hygienists reported that all children were given information on diet, hygiene, and fluoride. Most of the preventive practices of dental hygienists reflected limited changes in the period 1995 to 2004. However, the hygienists had reduced the use of fluoride varnishes and less often recommended fluoride tablets. The majority of hygienists reported that they individualized clinical prevention, while individual oral health information was standardized and given to all children. The results indicate that in 2004 a preventive approach combining individual information for all with intensified clinical prevention for children considered at risk was followed in child dental care.

Cariogram--a multifactorial risk assessment model for a multifactorial disease

This paper reviews some common methods for the assessment of caries risk. It also describes a new way of illustrating the caries risk profile of an individual, the Cariogram. Past caries experience and socioeconomic factors are often used for prediction of caries. As prediction models, the methods are simple, inexpensive and fast. However, they are not risk models, as they do not specify which particular risk factors are operating. Various biological factors can be used for risk assessment. Common ones are bacteria, diet and host factors. Taken separately, these biological factors often have limited predictive values. Socioeconomic factors often have a heavy impact on the biological factors as they can explain why an individual, for example, has a cariogenic diet or neglects oral hygiene. The biological factors are the immediate cause of the cavities. Caries experience is an illustration of how the host copes up with the biological activity. To facilitate the interpretation of biological data, the Cariogram was developed. It is a computer program showing a graphical picture that illustrates a possible overall caries risk scenario. The program contains an algorithm that presents a 'weighted' analysis of the input data, mainly biological factors. It expresses as to what extent different etiological factors of caries affect caries risk. The Cariogram identifies the caries risk factors for the individual and provides examples of preventive and treatment strategies to the clinician.

Sociobehavioural risk factors in dental caries - international perspectives

Diseases probably have their roots in a complex chain of environmental and behavioural events which are shaped by broader socioeconomic determinants. Most studies of sociobehavioural risk factors in dental caries have been carried out in industrialized countries, but such reports from low- and middle-income countries have been published in recent years. World Health Organization international collaborative studies and other international studies of social factors in dental caries using the same methodology provide empirical evidence of social inequality in oral health across countries and across oral health care systems. The paper highlights the challenges to dental public health practice, particularly the importance of risk assessment in estimating the potential for prevention. In future public health programmes, systematic risk factor assessment may therefore be instrumental in the planning and surveillance of oral health promotion and oral disease intervention programmes.

Effect of School-Based Fluoride Varnish Programmes on Approximal Caries in Adolescents from Different Caries Risk Areas

The aim was to evaluate, in a 3-year RCT study, school-based fluoride varnish programme on approximal caries incidence and approximal caries progression in 13- to 16-year-olds in high, medium and low caries risk areas on the Swedish west coast. Seven hundred and fifty-eight (89%) fulfilled the trial. Using a simple mobile unit, 2 dental nurses treated the adolescents with F varnish: (1) twice a year at 6-month intervals, (2) 3 times a year within 1 week, (3) 8 times per year during the semesters with 1-month intervals, and (4) no treatment (control). Radiographic caries recording was performed blindly by one of the authors. Concerning total approximal caries incidence, control groups in all areas developed more caries than F varnish groups, with the largest difference in the high risk area: 3.05 +/- 3.37 new approximal caries lesions (mean +/- SD) compared to 0.54 +/- 1.26 for group 3, 0.95 +/- 1.67 for group 1 and 1.40 +/- 1.89 for group 2 (p < 0.001). More than 90% of the new approximal lesions in all the groups and in all areas consisted of new enamel lesions. Regarding progression of enamel lesions, there were only significant differences between groups 1-3 and group 4 in the high caries risk area. Prevented fraction for fluoride varnish treatment twice a year at 6-month intervals was 69% in high, 66% in medium and 20% in low risk areas. To conclude, school-based F varnish treatment every 6 months in 13- to 16-year-olds is excellent to prevent approximal caries in medium and high caries risk areas.

The effect of five years' implementation of caries-preventive methods in Swedish high-risk adolescents

AIM

To study the effectiveness of four different preventive programmes within a group of adolescents at high risk of caries.

SUBJECTS AND METHODS

In 1995, a cohort of 12-year-olds was examined for caries and completed a questionnaire. Subjects identified as being at high risk were examined every year until 2000 when they were 17 years old. This high-risk group was subdivided into four groups, each individual randomly assigned to one of four preventive programmes: (A) information on tooth-brushing techniques; (B) prescription of fluoride lozenges; (C) semi-annual applications of fluoride varnish; (D) quarterly appointments where participants were given individualised information on oral hygiene and diet as well as an application of fluoride varnish. The outcomes examined were the caries increment in dentine, enamel and fillings. Poisson regression was used to assess the influence of background, preventive factors and habits.

RESULTS

The number of 12-year-olds in the high-risk group was 1,134 in 1995, of which 925 were still participants in 2000. The differences between the programmes in mean 5-year increment were not significant. Less risk of caries increment was shown for those who had at least one sealant and for those who belonged to the fluoride varnish group (C). A higher risk was observed for adolescents from working-class homes, and for those who reported often eating sweets and not brushing their teeth twice a day at all examinations during the whole study period.

CONCLUSIONS

The preventive programmes tested were equal in showing low efficiency in adolescents with high caries risk.

Grouping of tooth surfaces by susceptibility to caries: a study in 5-16 year-old children

BACKGROUND: The decline in caries has slowed and this may be indicative of variation in the susceptibility of differing teeth to caries. This study tests the hypothesis that in children, there are groups of tooth sites that exhibit differences in caries susceptibility. METHODS: Probit analysis of caries data collected from a 4-year longitudinal study of 20,000 schoolchildren aged between 5 and 16 years in 10 differing locations in the United States. RESULTS: The development of dental caries within the mouth followed a fixed hierarchy indicating that tooth surfaces show variation in caries susceptibility. Certain teeth and tooth sites have similar susceptibilities and can be grouped, the sizes of the groups vary. The most susceptible group consists of six tooth surfaces: the buccal pits and occlusal fissured surfaces of the first molar teeth. The second group consisted of 12 sites on the second molar and premolar teeth. The group formed by the least susceptible sites included the largest number of tooth surfaces and consists of the majority of the lower anterior teeth and canines. CONCLUSION: Variation in the caries susceptibility of tooth surfaces exists. Surfaces can be grouped according to caries susceptibility. An effect that reduces the cariogenic challenge of one of the sites within a group is likely to affect all the other sites within the particular group.

A cluster analysis model for caries risk assessment

Cluster analysis was applied to determine, the natural grouping of individuals, among sixty 8-10-year-old children, and to identify the most significant set of markers for risk assessment. The risk clusters were obtained with initial clinical and bacteriological measurements including dmf + DMFS, active caries, mutans streptococci and lactobacilli counts in plaque or saliva on two media, and Snyder's test results. The morbidity clusters were constructed with the final clinical indexes and incidence after 18 months (dependent variables). A risk cluster was identified that included the following significant initial variables; dmf + DMFS, active caries, counts of mutans streptococci from plaque on TSY20B and lactobacilli in saliva, and Snyder's test results. This set of markers identified 86% of the children at high risk who developed high morbidity, as well as 94% of children in the low-risk cluster who developed low or no caries. The results of this investigation provide the basis to develop a system for caries risk assessment.

Identifying children with dental care needs: evaluation of a targeted school-based dental screening program

OBJECTIVES

It has been suggested that changes in the distribution of dental caries mean that targeting high-risk groups can maximize the cost effectiveness of dental health programs. This study aimed to assess the effectiveness of a targeted school-based dental screening program in terms of the proportion of children with dental care needs it identified.

METHODS

The target population was all children in junior and senior kindergarten and grades 2, 4, 6, and 8 who attended schools in four Ontario communities. The study was conducted in a random sample of 38 schools stratified according to caries risk. Universal screening was implemented in these schools. The parents of all children identified as having dental care needs were sent a short questionnaire to document the sociodemographic and family characteristics of these children. Children with needs were divided into two groups: those who would and who would not have been identified had the targeted program been implemented. The characteristics of the two groups were compared.

RESULTS

Overall, 21.0 percent of the target population were identified as needing dental care, with 7.4 percent needing urgent care. The targeted program would have identified 43.5 percent of those with dental care needs and 58.0 percent of those with urgent needs. There were substantial differences across the four communities in the proportions identified by the targeted program. Identification rates were lowest when the difference in prevalence of need between the high- and low-risk groups was small and where the low-risk group was large in relation to the high-risk group. The targeted program was more effective at identifying children from disadvantaged backgrounds. Of those with needs who lived in households receiving government income support, 59.0 percent of those with needs and 80.1 percent of those with urgent needs would be identified.

CONCLUSIONS

The targeted program was most effective at identifying children with dental care needs from disadvantaged backgrounds. However, any improvements in cost effectiveness achieved by targeting must be balanced against inequities in access to public health care resources.

Caries experience and background factors in 4-year-old children: time trends 1967-2002

In cross-sectional studies conducted in 1967, 1971, 1976, 1980, 1987, 1992, 1997 and 2002, 4-year-old children in Umeå, a city in northern Sweden, were examined for dental caries and background factors such as oral hygiene habits, use of fluorides, and sugar consumption. The same methods and criteria have been used in each of the studies from 1967 to 2002. The number of children with caries had declined from 87% in 1967 to 42% in 1987, but then the decline levelled out. In 2002, 46% of the children had caries with a mean dmfs value of 2.0 +/- 3.6. Six percent of the children had 10 or more dmfs. Immigrant children had a higher caries prevalence (p < 0.01). A significant difference in the dmfs values was found in children according to tooth-brushing frequency (p < 0.01). Although the consumption of sugary products between meals increased between 1987 and 1997, no changes were noted from 1997 to 2002. In conclusion, no important changes in caries prevalence have taken place during the last 15 years. The frequency of tooth-brushing and immigrant background had a significant association with caries prevalence.

Measuring inequalities in the distribution of dental caries

OBJECTIVES

To evaluate different measurements of prevalence and inequality in the distribution of dental caries as to their partial collinearity, and ability in expressing associations with the supply of fluoridated tap water, indices of socioeconomic status and provision of dental services.

METHODS

The DMFT, the Significant Caries (SiC) Index, the proportions of children with high- (DMFT > or = 4) and rampant- (DMFT > or = 7) caries experience, caries-free children (DMFT = 0), the Gini coefficient and the Dental Health Inequality Index (DHII) were the dental outcomes appraised in a sample comprising 18 718 oral examination records for 11- and 12-year-old schoolchildren in 131 towns of the state of São Paulo, Brazil. Spatial data analysis assessed the association between aggregate figures of dental indices and several covariates.

RESULTS

The DMFT, the SiC Index and the proportions of children with high- and rampant-caries experience presented strong linear associations (Pearson r near or higher than 0.95), and an analogous profile of correlation with indicators of socioeconomic status, dental services and access to fluoride tap water. The same was observed for the DHII, the Gini coefficient and the proportion of caries-free children. These observations involve the perception of variables in each set as interchangeable tools for ecological studies assessing factors influencing, respectively, prevalence levels and inequality in the distribution of dental disease.

CONCLUSION

An improved characterization of the skewed distribution of caries experience demands the concurrent estimation of figures of prevalence and inequality in dental outcomes. This strategy may contribute to the design of socially appropriate programmes of oral health promotion.