Göran Koch, Sven Poulsen, Svante Twetman, and Christina Stecksén‐Blicks
Concepts of caries prevention
The first carious lesion and its restoration marks the initiation of a series of event that during the tooth’s lifetime will end up in more and more complicated restorations. Today there is sufficient scientific knowledge about the etiology of caries and about factors that interfere in this process in order for us to develop effective preventive strategies. This knowledge should be used to its full extent in an attempt to control caries.
Though recent decades have seen a reduction in dental caries occurrence (see Chapter 10), it is still a common disease of childhood and adolescence. Therefore, caries prevention should be given a high priority by the dental profession as well as by local and national health authorities. In this context, the pediatric dentist has a very specific responsibility in meeting the challenge to assist keeping children and adolescents free from caries. For example, very young children with early signs of caries should be given special attention, as they tend to develop more caries compared to children without early signs of caries (see Chapter 10).
Even if the principles of caries prevention are simple, the implementation, management, and evaluation of programs and recommendations can be difficult. For example, it has been shown in controlled clinical trials that professional removal of plaque every second week combined with strong motivational activities resulted in almost complete caries control in children [1], whereas a field study with a similar regimen but carried out with less enthusiasm or motivation did not give the same results [2].
Different terms are used to categorize preventive activities. Oral health promotion is an activity which takes place at the community level with the purpose of making it easier for people to live a healthy life through so‐called “healthy choices.” Systemic administration of fluoride through different vehicles is an example of an oral health promotion activity. Water fluoridation, introduced in the 1940s, has been found to be the easiest and cheapest method of systemic administration and caries reductions of 40–50% have been reported. It is recommended by the World Health Organization as an important caries‐preventive measure but its use is limited to large communities with water plants of high technical standard. In rural areas with small water plants and less control of the implementation, water fluoridation must be considered unrealistic. Long‐term systemic fluoride exposure via water during the period of tooth development and mineralization and thereafter throughout life has a documented caries‐reducing effect in both children and adults. However, the caries reduction from community water fluoridation is now considerably less than when the method was introduced, mainly because of the increased exposure to other fluoride sources such as food, beverages, toothpastes, and topical agents. In areas without access to optimal levels of fluoride, and not established fluoridation programs addition of fluoride to milk or table salt has been recommended and tested, but the preventive effects are unclear (See: World Health Organization. Oral Health: Action plan for promoting and integrated disease prevention. Resolution WHA 60.17 May 2007. Geneva:WHO).
In addition, there has been an increasing scientific understanding and also acceptance that systemic administration of fluoride pre‐eruptively has little effect in a caries‐preventive perspective. Much of the effect of systemic application of fluoride has been explained by the simultaneous topical fluoride exposure posteruptively. So, if fluoride tablets are used they should be sucked or chewed.
Reducing schoolchildren’s access to sweet snacks through school policies is another example of oral health promotion. An important aspect of oral health promotion is that it may also result in the reduction of other health problems such as being overweight, because many health problems have common risk factors (the “common risk factor approach”: see Chapter 10). In contrast to health promotion, prevention aims at reducing the risk of a specific disease. Prevention is described at three levels: primary, secondary, and tertiary:
· primary caries prevention is preventing new caries lesions from occurring
· secondary caries prevention is early detection and intervention to arrest early caries lesions
· tertiary caries prevention is restoration of cavitated lesions in order to prevent further destruction, eventually leading to the loss of the tooth.
It can be argued that primary caries prevention in itself is not a meaningful category as all preventive methods can be categorized as both primary and secondary prevention. For example, fluorides in the biofilm slow down the biofilm activity and demineralization but also remineralize subclinical caries lesions and thus arrest their progression.
Evidence‐based prevention
Evidence‐based practice has now become the focus of all health care practices, including pediatric dentistry, and preventive care for children and adolescents. According to Sackett [3] evidence‐based care is “an approach to oral health care that requires the judicious integration of systematic assessments of clinically relevant scientific evidence, relating to the patient’s oral and medical condition and history, with the dentist’s clinical expertise and the patient’s treatment needs and preferences.” In pediatric dentistry – as in most other dental specialties – the scientific evidence for the efficacy of most of the interventions is relatively weak. In spite of this, the clinician has to approach a clinical problem according to his or her best ability, by balancing the three components of evidence‐based care shown in Figure 11.1.
Figure 11.1 The triad forming the base for evidence‐based practice.
The randomized controlled trial
The randomized clinical trial (RCT) is the most valid scientific method for assessing the efficacy of preventive methods and has been used for testing a number of caries‐preventive agents and procedures. New preventive methods are, however, continuously being launched. For this reason, the pediatric dentist needs a basic knowledge of the most important characteristics (Box 11.1) of RCTs on caries prevention to be able to assess the quality of trials, understand the results, and skillfully apply them in the development of effective and efficient preventive programs.
Box 11.1 Definitions of important characteristics for randomized controlled trials (modified from the Cochrane Handbook, Glossary of Terms, 2005)
· Randomized controlled trial (RCT): an experiment in which two or more interventions, possibly including a control or no intervention, are compared by being randomly allocated to participants.
· Bias: systematic error in results or interpretation.
· Confounder: a factor that is associated both with the intervention and with the outcome of interest.
· Drop‐out: loss of subjects in the trial due to withdrawal or exclusion.
· Random allocation: a method that uses the play of chance to assign participants to comparison groups in a trial, e.g., by using a random numbers table or a computer‐generated random sequence.
· A trial is double‐blind if neither the investigator nor the participants know the type of intervention given to each participant. A trial is single‐blind if either the investigator or the participants know the intervention given to each participant.
· A trial is placebo controlled when the control individuals receive a placebo that is similar to the active treatment being tested but without the active ingredient (e.g., an inactive pill, a nonfluoride‐containing toothpaste, a topical solution without the active ingredient being tested).
The strength of the RCT is its ability to eliminate bias through randomization and the use of blinding procedures. The design is shown in Figure 11.2. It usually runs for a minimum of 3 years and the efficacy of the method is assessed by calculating the difference in new caries lesions between a control group and the experimental group(s). When the first caries‐preventive trials of fluoride‐containing agents were conducted they comprised one or more experimental groups and a placebo‐treated control group. Since the caries‐preventive effect of fluoride agents is so well established it is no longer considered ethical to include nonfluoride‐treated groups in preventive trials of fluoride agents. Thus new preventive methods often have to be compared to groups receiving already implemented methods.
Figure 11.2 Basic design of the randomized controlled caries clinical trial. Study subjects should be assigned randomly to one or more experimental or intervention groups and a control or no intervention group. The outcome of the trial is measured by comparing caries increment in the group(s) from the beginning to the end of the trial (M1 to M2).
With today’s reduced level of caries in children and adolescents the size of the RCT becomes an important methodological issue. With the relatively high caries level 20–30 years ago, small sample sizes could still give sufficient statistical power. With the decrease in dental caries incidence, sample sizes of 1000 or more subjects per group may be necessary to give sufficient power to the trial. Some trials may require a sample size so large that they become unrealistic for logistic and other reasons. The statistical power of a trial is important for the interpretation of the results of the trial. A small trial might not have sufficient statistical power to detect an effect, and may erroneously be interpreted as “evidence of no effect,” while a correct interpretation is: “no evidence of effect.”
The efficacy is calculated as shown in Box 11.2:
· absolute difference
· prevented fraction
· number needed to treat.
Box 11.2 Calculation of measures of effect in randomized controlled clinical caries trials
Number needed to treat to save one DMFS (NNT): 1/(ΔC − ΔT), where ΔC is the mean DMFS increment in the control or comparison group and ΔT is the mean DMFS increment in the treatment group.
The calculation of these three measures is illustrated below.
|
Population A |
Population B |
|
|
DMFS increment |
DMFS increment |
|
|
Control or comparison group |
3.09 |
0.53 |
|
Test group |
2.32 |
0.40 |
|
Absolute difference |
0.77 |
0.13 |
|
PF |
25.0% |
25.0% |
|
NNT |
1.3 ≈ 2 |
7.7 ≈ 8 |
The data presented above demonstrate that the same PF (25%) will result in very different absolute differences in populations with high caries increments (as in population A, where 0.93 DMF surfaces are saved) and low caries increments (as in population B, where 0.16 DMF surfaces are saved). In population A two patients would have to be treated in order to save one DMFS compared to eight in population B.
Absolute differences are dependent on the level of disease in the population, and will have to be recalculated as Prevented Fractions (PF) in order to apply to other populations. PF may, however, be misleading when it comes to deciding on implementation in the field, since high percentage reductions may be of little practical importance in populations with low caries activity. Number needed to treat (NNT) is now also calculated as it has the advantage of giving the clinician an impression of how many individuals have to be treated in order to obtain an effect.
Where to find the evidence
For the pediatric dentist it will be impossible to keep up with the RCTs published in the literature for several reasons. First of all, the literature is large, and constantly growing. Second, the methodology – especially the statistical procedures for analysis – is beyond the competencies of a practicing dentist. Finally, it will be difficult to synthesize the information from the many individual trials to decide on what to do for a given patient or community. Clinicians find review literature (secondary literature), which summarizes RCTs more relevant and easier to understand (Box 11.3). The most valid kind of secondary literature is the systematic review, which is a highly formalized review procedure based on systematic search strategies of the literature, critical appraisal, and analysis of the evidence from the literature. The most well‐known systematic reviews are undertaken by the Cochrane Collaboration (www.cochrane.org). Other organizations are, however, also performing systematic reviews of relevance to the pediatric dentist, e.g., SBU (www.sbu.se), NICE (www.nice.org.uk), and SIGN (www.sign.ac.uk). In Box 11.4 examples of reviews on the effect of topical fluorides on caries are presented.
Box 11.3 Definition of primary, secondary and gray literature, meta‐analysis and systematic reviews
· Primary literature: literature that reports results from original studies, e.g., RCTs.
· Secondary literature: literature that summarizes results from original studies, e.g. narrative reviews and systematic reviews (see below). Narrative reviews have a higher risk of bias and are graded lower than systematic reviews (see below).
· Gray literature: literature produced on all levels of government, academics, business and industry in print and electronic formats, not controlled by commercial publishing but protected by property rights, e.g., reports, conference abstracts and doctoral theses.
· Systematic reviews: a review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review.
· Meta‐analysis: the use of statistical techniques in a systematic review to integrate the results of studies. The studies involved in the meta‐analysis should be homogenous.
Box 11.4 Examples of systematic reviews on the effect of topical fluorides. SBU, Cochrane, NICE, and SIGN are examples of organizations that perform systematic reviews in health technologies
www.sbu.se. www.thecochranelibrary.com. www.nice.org.uk. www.sign.ac.uk
Fluoride toothpaste
Marinho VC, Higgins JP, Sheiham A, Logan S. Combinations of topical fluoride (toothpastes, mouthrinses, gels, varnishes) versus single topical fluoride for preventing dental caries in children and adolescents. (2004)
Marinho VC, Higgins JP, Sheiham A, Logan S. One topical fluoride (toothpastes, or mouthrinses, or gels, or varnishes) versus another for preventing dental caries in children and adolescents. (2004)
Santos AP, Nadanovsky P, de Oliveira BH. A systematic review and meta‐analysis of the effects of fluoride toothpastes on the prevention of dental caries in the primary dentition of preschool children. (2012)
Santos AP, Oliveira BH, Nadanovsky P. Effects of low and standard fluoride toothpastes on caries and fluorosis: systematic review and meta‐analysis. (2013)
Twetman S, Axelsson S, Dahlgren H, Holm AK, et al. Caries‐preventive effect of fluoride toothpaste: a systematic review. (2003)
Wong MC, Glenny AM, Tsang BW, Lo EC, et al. Topical fluoride as a cause of dental fluorosis in children. (2010)
Walsh T, Worthington HV, Glenny AM, Appelbe P, et al. Fluoride toothpastes of different concentrations for preventing dental caries in children and adolescents. (2010)
Fluoride supplements
Benson PE, Parkin N, Dyer F, Millett DT, et al. Fluorides for the prevention of early tooth decay (demineralised white lesions) during fixed brace treatment. (2013)
Cagetti MG, Campus G, Milia E, Lingström P. A systematic review on fluoridated food in caries prevention. (2013)
Azarpazhooh A, Main PA. Fluoride varnish in the prevention of dental caries in children and adolescents: a systematic review. (2008)
Marinho VC, Worthington HV, Walsh T, Clarkson JE. Fluoride varnishes for preventing dental caries in children and adolescents. (2013)
Tubert‐Jeannin S, Auclair C, Amsallem E, Tramini P, et al. Fluoride supplements (tablets, drops, lozenges or chewing gums) for preventing dental caries in children. (2011)
How does caries develop?
An important basis for prevention is an understanding of causation. In epidemiology, a cause is defined as a factor that influences the risk of disease, and causal factors are often arranged in what epidemiologists know as “webs of causation.” This concept has been used as a model for understanding dental caries [4], and Box 11.5 illustrates how causes of, e.g., early childhood caries can be identified and operated at several different levels:
· at the tooth surface, where a complex interplay takes place between host factors, diet, and the biofilm
· in the interaction between members of the family
· in the living conditions of children and their families.
Box 11.5 How the causal web can be used to understand causes of caries at many different levels
To the left of the figure below is a common childhood health problem, asthmatic bronchitis, which in itself is caused by a number of factors relating to living conditions, genetic background, etc., as indicated by the arrows to the far left. Children with asthmatic bronchitis often suffer from infections and fever, and may have an increased intake of juice to secure sufficient liquid intake. Parents of asthmatic children may give lower priority to daily toothbrushing. Finally, the medication itself may result in salivary changes increasing the risk of caries. The pie charts to the right indicate which of the component causes are influenced.
This understanding has given rise to the concept of “upstream” and “downstream” causal factors. Downstream causal factors are those that are active close to where the caries lesion is observed, i.e., at the tooth surface; while upstream factors are those that affect the living conditions of the family. It is important to underline that it is the responsibility of pediatric dentists to try to reduce causal factors for dental caries at all levels. This means understanding and being interested in health promotion to improve general living conditions and health of children, as well as using all possible methods of prevention to prevent new caries lesions from occurring, and to detect and arrest early initial lesions. The remaining part of this chapter is mainly concerned with caries risk assessment and prevention, and is based on an understanding of the disease as being multifactorial and caused by the interaction between the biofilm, the substrate available for the biofilm, and host factors. The model developed by Rothman et al. [5] for understanding complex diseases and conditions may help in structuring our thoughts (Figure 11.3). According to this model, disease occurs when a set of component causes (in the case of caries: biofilm, sugar, and unfavorable host factors) combine to constitute a sufficient cause.
Figure 11.3 A conceptual model, where disease is explained as occurring when a number of component causes (sections of the circle) act together to form a sufficient cause (closed circle). (a) High level of plaque, high sugar intake, and high susceptibility to caries will result in a caries lesion. (b) If the sugar intake is reduced, (c) if the plaque level is reduced, or (d) if the susceptibility is decreased, caries lesions will not occur.
Caries risk assessment
A structured caries risk assessment is the clinical process of evaluating the patient´s caries risk factors and judging whether these will outweigh the preventive factors. Thereby, it is an essential component in the decision‐making process for adequate prevention and management of dental caries and for individual timing of follow‐up and recall intervals [6]. Ideally, etiologic risk factors or non‐etiologic risk indicators should forego the disease in order to institute upstream prevention. The clinical risk assessment process is sometimes mixed up with caries prediction, which is the scientific/statistical modeling of factors related to caries development in populations or defined groups of people. The validity of caries predictors is determined in prospective trials without any intervention and the outcome is expressed in continuous values such as sensitivity and specificity (Box 11.6). The sensitivity and the specificity can vary between 0 and 1, the higher the better in terms of accuracy. When the sum of sensitivity and specificity is 2, the predictor, or combination of predictors, is perfect. It is however important to underline that such predictive values only are “true” under the conditions of that specific investigation and the external validity is limited. Nevertheless, findings from predictive studies are often extrapolated to the practitioner’s situation. An individual caries risk assessment can only be proven right or wrong; the paradox is that the skilled clinician, making a correct risk assessment with subsequent adequate and effective primary prevention, may turn out to be “wrong.” Consequently, caries risk assessment is an inexact science that is difficult to master with high quality studies.
Box 11.6 Calculation of sensitivity, specificity and predictive values. Adapted from Twetman & Fontana, 2009 [25]
Two‐by‐two table showing how to calculate sensitivity, specificity, and predictive values from data collected in prospective studies. In this case, the risk factor (predictor) for caries development was sugar consumption. The calculated values range from 0 to 1 but are sometimes expressed as percent
|
Caries active |
Caries inactive |
|
|
Risk factor present (high sugar intake) |
A = true positive (correct) |
B = false positive |
|
No risk factor (low sugar intake) |
C = false negative |
D = true negative (correct) |
Sensitivity (A/A + C) is the proportion of subjects with high sugar consumption and new caries lesions
Specificity (D/B + D) is the proportion of subjects with low sugar consumption and no disease activity
Positive predictive value (A/A + C) expresses the probability to develop caries with a positive risk factor
Negative predictive value (D/C + D) is the probability to remain caries‐inactive with a negative risk factor
As caries is a biofilm‐mediated multifactorial disease, it is generally understood that a comprehensive risk assessment should be based on a range of risk factors associated with the disease that are balanced against a range of protective factors to which the patient may be exposed (Figure 11.4). Thus, multiple variables based on socio‐economy, lifestyle, behavior, general health, diet, oral hygiene, clinical observations, and past caries experience are commonly proposed, varying with the age group at which they are targeted. According to the current risk profile, the patient is then grouped into one of several fixed risk categories (e.g., low risk, moderate risk, or high risk). The higher the risk, the more extensive preventive care should be and offered. Likewise, a higher risk calls for more frequent follow‐ups.
Figure 11.4 Caries balance as influenced by social, behavioral, and biological factors.
Risk ages
A clinical risk assessment should always be performed at the child’s first visit and then regularly throughout childhood since up to 50% of all children may change their risk category for better or for worse. It is also important to conduct caries risk assessments linked to social or medical life events such as onset of chronic diseases, disabilities, feeding problems, and divorce in the family. An additional strategy is to utilize the “risk age concept” which means that more or less all children exhibit increased caries risk at certain ages. The first period in life which merits special attention is 1–3 years during which the primary teeth are erupting. Several studies have emphasized the importance of an early risk assessment at one year of age in order to combat early childhood caries by assisting parents to establish good oral habits. Such activities are of special importance in vulnerable or immigrant groups. The second risk period in life appears at 5–7 years when the first permanent molars erupt with caries‐susceptible fissures that could be addressed with a structured sealant program. Finally, the turbulent teenage period (12–15 years) offers a high number of newly erupted molars and premolars susceptible for decay that warrants a risk‐based preventive approach.
Accuracy of caries risk estimations
A recent systematic review has evaluated the quality of evidence and ability of multivariate models and single factors to correctly identify future caries development in children [7]. The main results are summarized in Table 11.1. Despite extensive research, it seems obvious that there is no perfect or superior model or method to predict caries in children. In general, the clinical variables were stronger than the nonclinical and short‐term predictions (up to 2 years) were more reliable than long‐term predictions. Moreover, the multivariate models and baseline caries prevalence performed better in preschool children than in schoolchildren and adolescents. Sensitivity and specificity values above 0.8 are considered acceptable for caries risk and this could be reached with “best scenario” multiple models when applied to young preschoolers [8]. Past caries experience (dmfs/DMFS) was the most powerful single predictor in all age groups while quantification of bacteria levels in saliva displayed a high specificity but a poor sensitivity. In general, the probability of correctly identifying true high‐risk individuals was somewhat lower than the probability of finding the subjects with low caries risk. The quality of the evidence was generally low due to inconsistencies and study limitations [7].
Table 11.1 Accuracy and quality of evidence for various models and single factors to predict caries in children.
Adapted from the systematic review of Mejàre et al. 2014 [7]. Reproduced with permission of Taylor & Francis
|
Age group/risk factor |
Accuracy1 |
Quality of evidence2 |
|
Preschool children |
||
|
Multivariate model |
good/moderate |
⊕⊕OO |
|
Baseline caries prevalence |
good/moderate |
⊕⊕OO |
|
Socio‐demography/economy |
limited/poor |
⊕⊕OO |
|
Dietary habits/attitudes to diet |
poor |
⊕⊕OO |
|
Oral hygiene/use of fluoride |
poor |
⊕⊕OO |
|
Mutans streptococci/lactobacilli |
poor |
⊕⊕OO |
|
Schoolchildren and adolescents |
||
|
Multivariate model |
limited |
⊕⊕OO |
|
Baseline caries prevalence |
limited |
⊕⊕OO |
|
Dietary habits |
limited |
⊕⊕OO |
|
Oral hygiene/use of fluoride |
insufficient |
⊕OOO |
|
Mutans streptococci/lactobacilli |
insufficient |
⊕OOO |
|
Post‐eruptive age |
moderate |
⊕⊕OO |
1 The accuracy (utility) of models and single predictors was graded in three levels according to the sum of sensitivity and specificity: ≥1.5 = good/moderate; <1.5 ‐ ≥1.3 = limited, and <1.3 = poor.
2 According to GRADE: Strong (⊕⊕⊕⊕): Based on high or moderate quality studies containing no factors that weaken the overall judgment; Moderate (⊕⊕⊕O): Based on high or moderate quality studies containing isolated factors that weaken the overall judgment; Low (⊕⊕OO). Based on high or moderate quality studies containing factors that weaken the overall judgment; Very low (⊕OOO). The evidence base is insufficient when scientific evidence is lacking, quality of available studies is poor or studies of similar quality are contradictory.
Practical considerations
A caries risk assessment should be an integrated part of the clinical process. For a comprehensive caries risk assessment, it is advisable to collect information from the case history, clinical and radiographic examinations, and supplementary tests.
Case history
The case history should cover the child’s social situation, medical background, and current medication. There are few general diseases that directly affect the teeth but the medication in combination with demanding care and parental anxiety may move the focus from normal oral care routines. Some drugs have a high content of sugar and/or a low pH and the depressing influence on saliva secretion is a clear risk for caries development. Neuropsychiatric or functional disorders such as attention deficit hyperactivity disorder (ADHD) are linked to impaired dental health. Poor economy and a troubled family or social situation can also contribute to neglected oral health routines and unhealthy eating. The collection of a dietary history gives important information on frequency and the total sugar intake that provides a starting point for motivational interviews. Information on present and past fluoride exposure as well as the current oral hygiene routines should also be used in the risk assessment process.
Clinical examination
The clinical examination provides information on the past and current caries situation and the prevalence is an indication of host susceptibility. It is important that the teeth are examined dry and clean in order to be able to detect early signs of enamel demineralization as an indication of an active caries process. The extension and appearance of such early lesions should be carefully assessed. For example, a whitish rough area in the enamel with loss of luster along the gingival margin is more likely to be active than a brownish shiny area with smooth surface. Furthermore, lesions could be staged as initial, moderate, or extensive to facilitate estimations of progression. Local aggravating factors such as crowded arches, deep fissures, and enamel morphology should also be taken into consideration. The level of oral hygiene can be estimated with a disclosing solution. The presence of gingivitis and visible plaque on the labial surfaces of maxillary incisors of a toddler may be a marker of risk.
Supplementary tests
Supplementary saliva tests can contribute with useful information on factors of importance for the caries process. Hyposalivation occurs rarely among children but estimations of the salivary secretion rate are important in medically compromised children. In childhood, the stimulated secretion rate is dependent on age and cooperation. For schoolchildren, stimulated values less than 0.5 mL/min should be considered low. Simple chair‐side tests can provide additional information on salivary buffer capacity and counts of aciduric bacteria (mutans streptococci and lactobacilli) as biomarkers of a cariogenic environment. In infants and toddlers, bacteria sampling can be carried out with the aid of a wooden cotton pin that is wetted in saliva and streaked along the gingival margin of the upper incisors. The pin is then rolled on the chair‐side tests for subsequent cultivation.
Some key factors that affect caries risk are listed in Table 11.2. There are several formal and informal methods and models available to establish a child’s caries risk profile and to compile the obtained data for risk categorization. According to a questionnaire, most dentists make an informal and subjective evaluation of their child patients based on previous caries, oral hygiene, saliva flow, and “gut feeling” [9,10]. Only 14% used a pre‐formed template or computer software [9]. It has been demonstrated that such algorithm‐based models increase both objectivity and consistency and must therefore be regarded as best clinical practice [11]. The accuracy per se may however not be significantly increased but the educational and interactive nature of a computerized risk assessment program makes them useful in patient communication and motivation. An example of such program, the Cariogram, is shown in Figure 11.5. Digital dental records are obtainable with some form of risk assessment tool integrated into the system but unfortunately, to date, none of them are validated against the true outcome.
Table 11.2 Example of factors that may affect caries risk in children
|
Low caries risk |
Elevated caries risk |
|
Medical background |
|
|
|
|
Family and socio‐economy |
|
|
|
|
Oral hygiene |
|
|
|
|
Diet |
|
|
|
|
Caries |
|
|
|
Figure 11.5 Caries risk assessment with Cariogram. Ten variables are computed and the program indicates a 44% chance of avoiding new caries lesions in the near future (green sector). The blue sector indicates that high sugar amounts and frequent intakes are the main contributing factor in this case. Targeted preventive measures linked to the individual caries risk profile are suggested. The program is available in several languages at www.mah.se.
Methods for caries prevention
Collaboration and interaction
In order to prevent, reverse, or slow down caries lesions, one or several of the following factors have to be utilized or altered: topical application of fluoride, diet, oral hygiene, and fissure sealants.
There are both local and general interventions. Remineralization with fluorides or fissure sealants are examples of local treatments. General intervention or behavior change interventions are strategies to enable the patient to control his own risk factors. The method is to inform about the disease and risk factors and to improve the patient’s oral health knowledge, attitudes, and behaviors. It must, however, be emphasized that the factors should not be looked on as separate entities but as highly interactive. For example, good oral hygiene enhances the effect of topical fluoride applications.
Especially in young individuals, the cooperation, the knowledge, and the capability of the parents and the child are important factors for the outcome of the preventive measures. In Figure 11.6 three different results of preventive activities on caries progression are presented where the parental cooperation was determinant.
Figure 11.6 Caries progression. (a) An 11‐month‐old girl exposed to frequent intakes of stewed fruits. The parents could not change the diet. (b) One year later the incisors had to be extracted. (c) A 4‐year‐old boy with developing initial caries lesions. Good parental cooperation. (d) Status after 1 year shows no progression of the caries lesions. (e) A 6‐year‐old boy with active caries. Intense prophylaxis. (f) Status 1 year later shows complete control of caries progression.
Many interventions related to child dental health aim to reduce caries by encouraging the establishment and maintenance of favorable oral health routines as these behaviors, once established, can endure throughout adulthood and provide lifelong protection against caries. These interventions can be performed in different arenas such as child health centers, dental clinics, and schools. The approach should be health promoting and deal with the conditions of oral health and not only the causes of diseases.
Attitudes, appraisals, and cooperation as well as social, ethnic, and economic circumstances in the family may act as barriers or facilitators for implementation of interventions. Limitations to assimilate information due to language problems are important for the compliance with interventions. Additionally, parents’ habits have impact on child behavior, particularly through modeling actions. Also parents’ perception of their own ability to deliver the behavior desired for dental health of the child, i.e., regular toothbrushing (self‐efficacy), may have a significant impact on child dental health. Parental cultural beliefs and influences, the parent’s level of autonomy in decision‐making within the family, coping skills and supportive networks, as well as parents’ past dental experiences are important for their self‐efficacy.
Behavior change interventions
Motivational interviewing (MI) is a technique for behavior change interventions defined by Miller and Rollnick in 2002 [12]. It is an individually tailored conversation technique for strengthening a person’s own motivation and commitment to change habits. The technique aims to strengthen the motivation for and movement toward a specific goal by eliciting and exploring the person’s own reasons for change within an atmosphere of acceptance and compassion. The principle of MI is to try to understand through an empathetic and reflective listening and not argue when the patient does not see any reason to change, but instead try to understand why and strengthen the patient’s belief in his own ability and the possibility of change. The therapists should help the patient to articulate his own understanding of his problems, his own arguments for changes, and to strengthen his determination and commitment to implement the change. The effectiveness of MI at improving oral health is still, however, inconclusive according to a recent systematic review [13].
Topical application of fluoride
Topical fluoride application is one of the most effective ways of preventing caries. Numerous clinical studies have been performed over the last few decades. Although the trials differ concerning sample size, age of the children, diagnostic criteria, caries activity, and methods of fluoride application, there is, without doubt, documentation for a considerable caries‐reducing effect of topical fluoride application. For detailed information the reader is referred to specialist textbooks and reviews on the use of fluoride in dentistry (Box 11.4). Generally, there is one important basic principle to obtain a good effect: apply fluoride in such a way that fluoride is present at the plaque/enamel interface where it will control dissolution and stimulate precipitation of minerals during caries challenges. This can be achieved by frequent application of low concentration fluoride solutions or preparations, or less frequent application of high fluoride concentration preparations causing fluoride deposits in or on the enamel that will slowly be released to the plaque–enamel interface. As a general rule the fluoride should match the caries activity of the child; that is, the greater the cariogenic challenge, the more intense the fluoride treatment.
Box 11.7 Relationship between cariogenic consumption, use of fluoride toothpaste, and enamel demineralization
The extent of demineralization of enamel slabs in situ in relation to consumption of sugar‐based solutions and daily brushing with fluoride or nonfluoride toothpaste was assessed. Mineral analysis revealed that when fluoride toothpaste was used, net demineralization was not evident until the frequency of sugar consumption was seven or more times a day. When fluoride‐free toothpaste was used, net demineralization occurred as early as three consumptions a day.
Source: Duggal et al. 2001 [27]. Reproduced with permission of Sage Publications.
The concept of how fluoride prevents caries has undergone a paradigmatic shift during recent decades. Previously, the assumption was that incorporation of fluoride in the enamel apatite lattice during tooth formation and mineralization resulted in a permanent or long‐lasting resistance of the enamel to dental caries. The present view on the mechanism of fluoride in caries prevention is that fluoride has to be present in the plaque fluid/biofilm during the caries challenge, slowing down the dissolution of enamel and supporting the precipitation phase. It has been found that topical application of fluoride results in the formation of calcium fluoride crystals accumulating on the tooth surface. When pH is lowered during an acidic challenge, the crystals are dissolved and provide fluoride ions which control the caries attack. Thus, topical applications that form calcium fluoride crystals constitute a pH‐controlled fluoride slow‐release system ready to act when necessary. In this context it is important to realize the limitations of the demineralizing controlling effect of topical fluorides in situations with frequent intakes of cariogenic products (Box 11.7).
The quality of evidence for caries inhibition caused by the most common methods of using fluorides is presented in Table 11.3. The quality of evidence is based on systematic reviews and graded in four levels according to a GRADE system; strong, moderate, low, and very low (www.sbu.se).
Table 11.3 Quality of evidence for various caries preventive methods in children
|
Dentition |
Effect/Prevented fraction |
Quality of evidence (GRADE) |
|
Primary |
||
|
Daily use of fluoride toothpaste |
19–27% |
⊕⊕OO |
|
Fluoride varnish |
37% |
⊕⊕OO |
|
Fluoride supplements (tablets, drops, lozenges or chewing gum) |
Unclear |
⊕OOO |
|
Fluoridated milk |
Unclear |
⊕OOO |
|
Permanent |
||
|
Daily use of fluoride toothpaste |
19–27% |
⊕⊕⊕⊕ |
|
Supervised toothbrushing |
31% |
⊕⊕⊕⊕ |
|
Fluoride mouth rinse |
24% |
⊕⊕OO |
|
Fluoride varnish |
43% |
⊕⊕⊕O |
|
Fluoride supplements (tablets, drops, lozenges or chewing gum) |
24% |
⊕OOO |
|
Effect of chlorhexidine varnish |
Unclear |
⊕OOO |
|
Fissure sealing with resin‐based materials on occlusal surfaces of permanent molars in individuals with high caries risk |
73–85% |
⊕⊕⊕O |
|
Self‐performed dental flossing |
No effect |
⊕OOO |
|
Tooth‐brushing instruction |
No effect |
⊕OOO |
|
Decreasing sugar intake < 10 E% |
Effect |
⊕⊕⊕O |
|
Polyols (xylitol) |
39% |
⊕⊕OO |
According to GRADE: Strong (⊕⊕⊕⊕): based on high or moderate quality studies containing no factors that weaken the overall judgment. Moderate (⊕⊕⊕O): based on high or moderate quality studies containing isolated factors that weaken the overall judgment. Low (⊕⊕OO): based on high or moderate quality studies containing factors that weaken the overall judgment. Very low (⊕OOO): the evidence base is insufficient when scientific evidence is lacking, quality of available studies is poor or studies of similar quality are contradictory.
Self‐applied fluorides
Fluoride toothpaste is the ideal vehicle to apply fluoride to teeth. Daily use of fluoride toothpaste will result in caries reductions of about 30% (GRADE is strong for permanent teeth and low for primary teeth). Small children usually swallow about 30% of the amount of toothpaste and for this reason it is important to control the amount of toothpaste they use. Children can start using fluoride toothpaste when the first primary teeth have erupted. The amount of toothpaste should be the size of the child’s little fingernail (Figure 11.7) and from the age of 5–6 years 1 cm of toothpaste can be used and from 11–12 years of age 2 cm of toothpaste. The fluoride concentration should be 1000 ppm F below 11–12 years of age and 1500 ppm F above that age.
Figure 11.7 The amount of fluoride toothpaste (little fingernail) for a 2‐year‐old child.
Fluoride mouthrinses commonly were used in school‐based programs with 0.2% NaF solution weekly or fortnightly during the 1960s to 1980s but ceased during later years as most children are using fluoride toothpaste. However, in child populations with high or increasing caries activity, fluoride mouthrinses have been reintroduced with a successful outcome. The effects of the rinsing programs are in the range of 20–25% caries reduction (GRADE is low). The best effect has been achieved by daily rinsings with 0.05% NaF solution. Mouthrinsing is not recommended for preschool‐aged children since they often swallow the rinse solution.
Fluoride sucking tablets and chewing gum can be a complementary fluoride treatment for children. Fluoride sucking tablets can be used from the age of 3 years and chewing gum from the age of 10 years in children with extreme caries activity (GRADE is very low). The administration of fluoride tablets should follow a dosage schedule adjusted to age and fluoride content of drinking water.
Professionally applied fluorides
Fluoride varnishes often contain high concentrations of fluoride and adhere to tooth surfaces for days, thus considerably increasing the fluoride content in the surface and subsurface enamel. The fluoride will then be slowly released to the plaque–enamel interface. The overall reduction in caries of about 40% (GRADE is moderate for permanent teeth and low for primary teeth). The varnishes are easy to apply and two applications a year will give a good effect.
Fluoride gels are available on the market with different fluoride concentrations and tastes. Most of them are slightly acidic to enhance the fluoride uptake in enamel. They are mostly applied in custom‐made trays and are used either in a professional setting or on a daily basis at home. Due to the risk of swallowing, they should not be used in preschool‐aged children. The indications are children with highly active caries and children with reduced salivation.
Dental fluorosis and toxicity
Dental fluorosis is a qualitative defect of enamel caused by the long‐term intake of fluoride during the period of tooth formation. The threshold dose for development of mild fluorosis in permanent teeth has been estimated as 40–100 μg F/kg body weight per day. However, it has been found that for the individual there are no threshold values below which fluorosis cannot occur. In many parts of the world, e.g., North America and Australia, trends towards increasing levels of mild dental fluorosis following fluoride supplementation have been reported. The reason may be increased ingestion of fluoride from water, food, beverages, and dentifrices during the period of tooth formation, in particular the first 0–4 years of life. Control and recommendations for fluoride intake are major obligations of the pediatric dentist. Thus it is important that the dentist knows the amounts of fluoride contained in the preparations used in dentistry for children (Box 11.8). It should be noted that only fractions of fluoride in toothpaste and rinses are ingested. Carefully, professionally applied topical fluorides and the correct use of fluoride toothpaste according to recommendations are not risk factors for dental fluorosis.
Box 11.8 Fluoride content in preparations used in caries prevention in children
|
Preparation |
Fluoride concentration (%) |
Amount used in a single application |
Fluoride dosage in a single application (mg F) |
|
Toothpaste |
|||
|
1500 ppm F |
0.15 |
0.6 g |
0.9 |
|
1000 ppm F |
0.1 |
0.6 g |
0.6 |
|
500 ppm F |
0.05 |
0.4 g |
0.2 |
|
Mouthrinse solution |
|||
|
0.2% NaF |
0.1 |
10 mL |
10 |
|
0.05% NaF |
0.02 |
10 mL |
2 |
|
Fluoride varnish |
|||
|
High fluoride (2.26% F) |
2.3 |
0.4 mL |
9 |
|
Fluoride gel |
|||
|
High fluoride |
1.23 |
5 mL |
62 |
|
Low fluoride |
0.1 |
5 mL |
5 |
Even if the concentrations and amounts of fluoride used in dental practice and in preventive activities outside the clinic are far below toxic thresholds (except for dental fluorosis), it is important to know the levels at which general toxic reactions can be expected.
Acute toxic dose
This situation may occur if 5 mg F/kg body weight has been ingested. The child will rapidly develop nausea and epigastric distress, often followed by vomiting. The child should be referred to hospital immediately for observation and emergency treatment. From reported cases it can be concluded that if a child ingests a fluoride dose in excess of 15 mg/kg body weight, death is likely to occur.
Recommendations
Some general recommendations for the use of fluorides are as follows:
· Use fluoride‐containing toothpaste twice a day when the first primary teeth have erupted.
· In areas with a general high caries activity, institute school‐based fluoride mouthrinsing programs.
· High caries risk patients should have individual fluoride programs based on fluoride mouthrinsings, fluoride varnishes, fluoride gels, or fluoride sucking tablets/chewing gum.
Diet
The relationship between diet and caries has been confirmed in numerous studies. As dental caries progresses with age, the effects of diet on the dentition are lifelong. Sucrose is particularly cariogenic due to its unique ability to support the synthesis of extracellular (water‐soluble as well as water‐insoluble) glucans by mutans streptococci. However, all fermentable carbohydrates can be metabolized by many different bacteria, including mutans streptococci, in the dental biofilm, and their acid byproducts can lead to demineralization of the tooth structure. This means that most food products and nearly all snacks, sweets, and soft drinks are potential caries risk factors. Lactose (milk sugar) has been shown to be less acidogenic than other sugars.
It is generally accepted that the caries risk from sugar is related to the consistency of the sugar‐containing foods and the frequency of its consumption. Distinctions are made between liquid and adhesive (sticky) foods. Frequency refers to the number of times per day that sugary foods are eaten. Both consistency and frequency affect the length of time that teeth are exposed to sugar. The relative importance of frequency versus the total amount of sugar consumption is not clear‐cut. There is scientific support from an extensive systematic review that less caries develops when the free sugar intake is less than 10% of the total energy intake [14]. In addition, in 2015 the World Health Organization presented guidelines on sugar intake to prevent and control unhealthy weight and dental caries (www.who.int/nutrition/publications/guidelines/sugars_intake/en/).
The caries challenge from the diet in the individual depends on the interaction with other risk factors such as reduced salivary secretion, poor oral hygiene and low fluoride exposure. The caries risk from sugar may thus be reduced with optimal salivary secretion, oral hygiene and topical fluoride exposure. Accordingly, an epidemiologic relationship between sugar and caries is not obvious in populations practicing toothbrushing with fluoride toothpaste. This knowledge underscores the importance of toothbrushing with fluoride toothpaste as a prevention method to counteract the caries challenge from the diet.
Dietary counseling
Inquiries into the dietary habits of patients are a necessary basis for advice concerning future changes in diet to prevent dental decay. It should be observed that it is difficult to obtain valid information on consumption and often the intake of healthy foods are overestimated and unhealthy foods are underestimated. The most valid methods of obtaining exact quantitative data from which to estimate consumption of different dietary items are inventory and weighing procedures. However, these are time consuming and do not lend themselves to practical use. It is more realistic to take a dietary history, which is a semi‐quantitative method where the patient or parents record all food consumption during a specific period of time, normally 3–7 consecutive days, on a specially developed form. A more simple “dietary habit evaluation” is frequently used. This method, based on questionnaires or interviews, concentrates on the number of intakes of well‐known cariogenic products, e.g., candy, soft drinks, and cookies. The number of such intakes per day or week is recorded and will form the basis for recommended changes in consumption patterns.
Without neglecting the general aspects of nutrition, the dentist should concentrate his or her efforts in diet counseling on advice on the consumption of cariogenic products. Thus, dietary counseling concerning improvement of dental health should be aimed at estimating the patient’s food habit pattern, the consumption of fermentable carbohydrates, in particular sucrose, and the intake frequency of snacks, sweetened beverages, and adhesive “sticky” food. Bottle feeding with sucrose‐containing fluids, especially at night, is an important factor that may cause rampant caries in small children.
With dietary counseling it is important to develop tools that are understandable and will help the child and family to change their dietary habits. Images with healthy and unhealthy food may lend support to patients with limited capacity to assimilate information due to language difficulties.
The general guidelines concerning diet and dietary habits to avoid caries are very simple:
· Restrict the frequency of meals and intakes to five or six per day. Usually this means three main meals and three intermediate meals or intakes. Try to avoid sucrose‐containing food products and beverages. No “snacking” between meals. Avoid bottle feeding with sucrose‐containing fluids, especially at night.
· Restrict candies and sweet snacks to once a week (“Saturday sweets”).
· If the intake of sweets and chewing gums cannot be avoided, use products sweetened with sucrose substitutes, e.g., xylitol and sorbitol.
· Advice on infant feeding in order to avoid early childhood caries (“baby‐bottle caries” or “nursing caries”).
· Advice on prevention of erosion, which means reduction of frequent intake of acidic beverages such as soft drinks, fruit juices, and sport drinks.
Sucrose substitutes
Since dental caries forms through a complex interaction over time between acid‐producing bacteria and fermentable carbohydrates, it has been an obvious idea to utilize sugar substitutes and artificial sweeteners in order to prevent the disease. Sucrose substitutes can be divided into non‐nutritious sweeteners and caloric sweeteners obtained from natural sources. The most widely used sugars in “tooth‐friendly” products such as chewing gums, tablets, and candies are the sugar alcohols xylitol, sorbitol, mannitol, maltitol, and lactitol. Xylitol has been assumed to have specific anticariogenic properties. A systematic literature review, however, found the evidence in support of xylitol over sorbitol as contradictory [15]. The antibacterial effects are based on metabolic reactions; xylitol is incorporated by oral bacteria with the fructose‐specific phosphotransferase system and phosphorylated to xylitol‐5‐phosphate. This substance hampers further cell metabolism and fewer acids are formed, limiting the pH drop in the oral biofilm. There are no absolute contraindications for the use of xylitol, but there is a European Union recommendation that the daily intake should be less than 3 g in children under 3 years of age. It is commonly recognized that high single doses may induce gastrointestinal upsets and soft stools in susceptible individuals.
Xylitol has been extensively studied in controlled trials as well as in field studies. In the pioneering “Turku sugar study” (1975) with almost complete substitution of dietary sucrose with fructose and xylitol, practically no caries lesions developed. Later studies have been conducted in children with a partial sugar substitution and significant reduction of caries lesions has been documented, especially in populations with high caries prevalence.
Clinical trials involving xylitol suggest that the intake of xylitol must exceed 5–6 g/day in fractioned doses to have a clinically significant effect on microbial growth and caries development. Many health organizations worldwide are supporting this recommendation for at‐risk populations. To reach definitive caries‐preventive/therapeutic recommendations well‐designed, placebo‐controlled randomized clinical trials (RCTs) focusing on efficacy, feasibility, adherence, dosage, vehicle, synergism with other preventive strategies are needed before sorbitol‐ or xylitol‐sweetened chewing gums can be considered as a public health measure. A major obstacle with the use of gums and tablets is the high frequency and large number of pellets that are required to deliver the therapeutic amounts. In addition, the costs for long‐term use may be restrictive.
An interesting approach to combat vertical transmission of MS between mothers with high MS levels and newborns is maternal xylitol consumption before and during eruption of the primary teeth of the child (Box 11.9).
Box 11.9 Combating vertical transmission of maternal mutans streptococci (MS)
The strategy to combat early vertical transmission of cariogenic bacteria from parents to their children is often named primary–primary prevention. The preventive intervention is usually directed to mothers of newborn babies with high counts of salivary MS and implemented before and during the eruption of the primary teeth.
A Finnish study showed in assumed high‐caries‐risk children that maternal consumption of xylitol‐containing chewing gums reduced maternal MS counts and at the age of 5 years the dentinal caries (dmf) was reduced in the child. A long‐term influence on the caries experience and need for restorative treatment up to 10 years of age of the child was seen. (Source: Laitala et al. 2013 [28])
Another Swedish study randomized mothers with high counts of salivary MS into three experimental chewing gum groups containing A) xylitol, B) chlorhexidine/xylitol/sorbitol, and C) sodium fluoride/xylitol/sorbitol. The intervention started when children were 6 months old and was terminated one year later. All of the mothers were instructed to chew one piece of the appropriate gum for 5 minutes, three times a day. At 4 years of age of the child less caries was observed in children of mothers who chewed gums with xylitol as the single sweetener during the time of eruption of the first primary teeth compared with those who used gums containing fluoride, sorbitol, and lower amounts of xylitol. At 10 years of age of the child there were no effect on caries with the xylitol intervention. (Source: Thorild et al. 2012 [29])
The studies were conducted in low‐caries communities and with parents with good compliance. No health economic analyses of the mother–child concept are yet available and studies in high‐caries groups are needed before any public‐based recommendations can be formed.
Based on current evidence the following guidelines may be considered:
· Products with sugar alcohols could be advocated for children and adolescents at high risk of caries as a supplement to daily fluoride exposure.
· Products that actively stimulate saliva secretion, such as chewing gums and sucking tablets, are the first choice.
· Products should contain as much sugar alcohols per unit as possible and preferable as the only sweetener.
· Intake should be fractioned at least three times over a day.
Plaque control
Toothbrushing
Proper oral hygiene can be achieved and maintained by mechanical and chemical means at home and at the dental office. There is little scientific evidence that toothbrushing per se can prevent dental caries, since normal brushing does not remove plaque from pits, fissures, and other retention sites. Tooth cleaning is, however, of particular importance in the maintenance of a healthy periodontium, and studies [16,17] have demonstrated a relationship between non‐brushing habits and gingivitis and early caries development in infants and toddlers. Toothbrushing skills must therefore be emphasized strongly and taught to children of all ages as well as their parents. It is important that parents are instructed to initiate toothbrushing from the eruption of the very first tooth and that a proper toothbrushing regimen should have been established when the first primary molars erupt. Parents should be shown a technique and be trained on how to use it. Since small children cannot keep up effective oral hygiene by themselves, parents must perform toothbrushing at least up to the age of 6 years and thereafter regularly supervise the procedure. The special problem associated with the cleaning of the first permanent molar should be underlined. A soft toothbrush of appropriate size and fluoridated toothpaste are the most effective aids for oral hygiene in the primary and mixed dentition. The use of disclosing tablets or liquids should be recommended when necessary. An electric toothbrush has a similar cleaning effect as manual brushing and may be a motivating tool for some children and an excellent help for disabled patients. Dental floss and toothpicks normally should be considered only for the fully erupted permanent dentition.
Some general recommendations concerning toothbrushing can be given:
· Toothbrushing should be initiated from the eruption of the first tooth and proper regular toothbrushing should have been established when the first primary molar is erupting.
· Brush the teeth twice daily: after breakfast and before bedtime.
· Select a soft brush with a small head and a large handle for the youngest children.
· Use a small amount of fluoridated toothpaste.
Antibacterial agents
The concept of using antibacterial agents to prevent and control caries in children dates back to the era of the “specific plaque hypothesis.” The background thinking was that causative cariogenic microorganisms could be suppressed by broad‐spectrum antiseptics (e.g., chlorhexidine) and thereby combat the disease. In the prospect of the ecological plaque hypothesis however, this strategy is questioned; caries is not a classical infectious disease with well‐defined pathogens but a result of an ecological shift in the commensal microbiome. Furthermore, recent research has provided insights that human biofilms play an important role for health and well‐being which applies also to the oral biofilm that actively contributes to the maintenance of oral health [18]. There are concerns that long‐term use of oral chemotherapeutics may have a negative influence on the diversity and stability of the oral biofilm, and therefore should be restricted. In this context, the use of harmless or beneficial bacteria has gained interest. Pre‐ and probiotic bacteria are “live microorganisms which when administered in adequate amounts confer a health benefit on the host” and such strains may help to maintain or restore a natural microbiome (homeostasis) by interference and/or inhibition of other microorganisms [19]. This concept has been a promising caries‐preventive adjunct to fluoride in pre‐school children but further research is needed to understand the mode of action [20]. Other promising antibacterial candidates are targeted antimicrobial peptides and the common amino acid arginine.
Among the antibacterial agents used in the oral cavity, chlorhexidine gluconate is considered the gold standard. The drug has a strong affinity to oral structures and interferes with cell wall transportation and metabolic pathways of susceptible Gram‐positive bacteria. Numerous clinical trials in children have shown that topical applications of chlorhexidine‐containing gels and varnishes can reduce the levels of mutans streptococci in saliva and plaque for a period up to 3 months, but the subsequent effect on caries formation and activity was inconsistent and inconclusive [21]. Likewise, attempts to prevent and arrest early childhood caries using chlorhexidine and/or povidone–iodine have been proven less successful. Thus, there is no evidence to suggest the use of chlorhexidine to prevent caries in children, not even in high‐risk subjects [22]. Chlorhexidine rinses can however still be a short‐term option for plaque control after oral surgery and for temporary support of oral hygiene in medically compromised and disabled children. The drug has a low toxicity and very few side‐effects except for tooth discoloration. The somewhat bitter taste may be unpleasant to children.
Fissure sealing
The distribution of caries within the dentition depends on the overall caries prevalence in the population. In low caries populations, the occlusal surfaces of permanent molars are the most vulnerable tooth surfaces in the dentition due to an anatomy that supports plaque retention, while the proportion of approximal caries increases in populations with higher caries prevalence [23]. Accordingly, the majority of new caries lesions in school‐aged children in low caries populations develop on occlusal surfaces of the first and second permanent molars. It is obvious with this background that a method aiming to prevent caries in pits and fissures would be relevant (see also Chapter 10).
Fissure sealing is a method by which a material is placed in the pits and fissures of teeth in order to prevent or arrest the development of caries. The intention is to prevent the growth of bacteria that promote caries development in pit and fissures. The material is retained on the enamel surface either through an acid‐etch technique or a chemical bonding of the material to the enamel surface, as in the case of glass‐ionomer‐based sealants.
Since the first resin‐based sealants were tested in the late 1960s and the early 1970s, a number of new materials have been introduced including fluoride‐releasing fissure sealants. The most commonly used materials are the light cured resin‐based sealants. Glass ionomer cements are the second main type of sealants. It has been assumed that these sealants can prevent caries through fluoride release, in spite of the poor retention of the material. Some sealants are clear, and others have a filler material added to improve their resistance against wear and visibility.
The efficacy of fissure sealants has been tested in a number of clinical trials that have evaluated the following outcomes: difference in caries increment in sealed and non‐sealed teeth, effect of different materials, as well as retention and safety of different materials. Most of these trials have been conducted using a split‐mouth design, where contralateral teeth are assigned randomly to sealing or control/comparison.
A Cochrane systematic review of clinical trials on fissure sealants includes 34 studies with 6529 children and adolescents, 5–16 years of age (Box 11.10). Based on the Cochrane review, the application of sealants is a recommended procedure to prevent or control caries. Sealants are effective in high‐risk children but the effect of sealants in children with low or moderate caries risk is not established, nor the relative effectiveness of different types of sealants. Sealants prevented caries in the first permanent molars in children, 5–10 years of age, between OR = 0.12 (95% CI 0.07 to 0.19) at 24 months and OR = 0.21 (95% CI 0.16 to 0.28) at 48–54 months. According to the review, depending on caries activity, caries was reduced between 73% and 85% (GRADE is moderate). The retention of resin‐based sealants is good, but poor for glass ionomers. The current evidence shows no adverse effects.
Box 11.10 Excerpt from abstract of a systematic review of fissure sealing published in the Cochrane Library
Objectives:
· To evaluate the caries prevention of pit and fissure sealants versus no treatment in children and adolescents. This was carried out for different background levels of caries in the population.
· To compare the effect of different sealant materials for preventing dental caries in children and adolescents.
Selection criteria: Randomised or quasi‐randomised controlled trials of at least 12 months duration comparing sealants for preventing caries of occlusal or approximal surfaces of premolar or molar teeth with no sealant or different type of sealant in children and adolescents under 20 years of age.
Main results: Compared to control without sealant, second or third or fourth generation resin‐based sealants prevented caries in first permanent molars in children aged 5 to 10 years (at 2 years of follow‐up) odds ratio (OR) 0.12, 95% confidence interval (CI) 0.07 to 0.19. If we were to assume that 40% of the control tooth surfaces were decayed during 2 years of follow‐up (400 carious teeth per 1000), then applying a resin‐based sealant will reduce the proportion of the carious surfaces to 6.25% (95% CI 3.84% to 9.63%); similarly, if we were to assume that 70% of the control tooth surfaces were decayed (700 carious teeth per 1000), then applying a resin‐based sealant will reduce the proportion of the carious surfaces to 18.92% (95% CI 12.28% to 27.18%). This caries‐preventive effect was maintained at longer follow‐up but both the quality and quantity of the evidence was reduced. There is insufficient evidence to make any conclusions about whether glass ionomer sealants, prevent caries compared to no sealant at 24‐month follow‐up (mean difference in DFS –0.18, 95% CI –0.39 to 0.03, one trial at unclear risk of bias, 452 children randomized, 404 children evaluated, very low quality evidence). Sealant compared with another sealant: the relative effectiveness of different types of sealants remained inconclusive in this review.
Authors’ conclusions: The application of sealants is a recommended procedure to prevent or control caries. Sealants are effective in high‐risk children but information on the magnitude of the benefit of sealing in other conditions is scarce. The relative effectiveness of different types of sealants has yet to be established.
Source: Ahovuo‐Saloranta et al. 2013 [24]. Reproduced with permission of John Wiley & Sons.
The use of fissure sealants in low‐caries‐risk populations has been questioned. However, dental caries is still a problem in some individuals in low‐caries prevalence populations. Fissure sealants of the occlusal surfaces of the permanent molars in high‐risk individuals provide an effective method for caries prevention in low‐caries populations [23]. It can be categorized as primary prevention but sealants can also be used to arrest micro‐cavities and non‐cavitated lesions (secondary prevention).
Preventive strategies
Preventive strategies can be classified into two different categories: population strategies and high‐risk strategies. An intermediate strategy is the high‐risk group strategy. The population strategy aims at a general reduction of risk factors for all individuals in a population, whether diseased or not. Examples of population strategies which have been implemented in Nordic countries are the now almost abandoned fluoride rinses, recommended use of fluoridated toothpaste, and advice to reduce sugar intake. A high‐risk strategy aims at targeting the program at those individuals with the highest risk. The underlying thinking is that scarce resources can be used for those individuals with the highest need. As mentioned above, an intermediate strategy would be a high‐risk group strategy, where the program aims at known high‐risk groups, such as certain groups of immigrants in an otherwise low‐caries population.
The marked improvement in oral health during recent decades has generated extensive interest among pediatric dentists in Nordic countries on preventive methods aiming at controlling the disease in individuals. A somewhat lower interest has been directed towards reducing the risk factors in the general population or subgroups. This may be problematic if we want to retain the low general level of disease in the population. Seen from this perspective, population strategies and high‐risk strategies should not be considered alternatives but should go hand in hand. Population strategies should aim at reducing the general level of the risk factors in the population, while high‐risk strategies should aim at controlling the disease in those individuals with early caries lesions (see Chapter 12). The systematic delivery system for oral health care for children and adolescents developed in Nordic countries makes this strategy very feasible to implement.
Earlier in the chapter the so‐called common risk factor strategy was mentioned [24]. This strategy is based on the fact that oral diseases share risk factors with a number of other chronic diseases. In children risk factors such as diet and hygiene are common to dental caries and periodontal disease as well as to obesity and skin diseases. If children’s dental health is to be improved through the common risk factor approach, the dental services have to collaborate with other actors in the social service sector and other health professionals.
Preventive and operative care: a coordinated approach
The integration of prevention (nonoperative methods) in treatment procedures of caries will be dealt with in detail in Chapter 12. However, some comments will be made on the use of the basic concepts of prevention when planning the treatment of children with high caries activity or caries risk. The placement of restorations in children with ongoing high caries activity is not a sound or fair treatment, either ethically or scientifically. The outcome of such treatment will always be poor. Therefore, a strategy has to be found where operative treatment is combined with control of disease activity.
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