Donald W. Lewis, DDS, DDPH, MScD, FRCDC; Amid I. Ismail, BDS, MPH, DrPH; the Canadian Task Force on the Periodic Health Examination
Canadian Medical Association Journal 1995; 152: 836-846
[résumé]
Dr. Lewis is a professor of community dentistry at the University of Toronto, Toronto, Ont., and Dr. Ismail is an associate professor and chair of the Department of Pediatric and Community Dentistry, Dalhousie University, Halifax, NS.
Copies of this and other task force reports are available from the Health Services Directorate, Health Programs and Services Branch, Health Canada, Tunney's Pasture, Ottawa ON K1A 1B4.
© 1995 Canadian Medical Association
Options: Systemic fluoride administration, professionally administered fluoride, use of fluoride mouth rinses, fissure sealants, oral-hygiene practices, dietary practices, identification of groups at a high risk of dental caries, and early diagnosis and treatment.
Outcomes: Reduced prevalence of dental caries and fluorosis, longer retention of teeth and lower treatment costs.
Evidence: Several MEDLINE searches were conducted for articles published from January 1980 to December 1992, including relevant review articles.
Values: Relevant clinical findings were evaluated and categorized with the use of the evidence-based methods and values of the Canadian Task Force on the Periodic Health Examination. Recommendations were developed for each method of caries prevention, with reduced incidence of dental caries and improved prevalence of caries-free teeth given high values.
Benefits, harms and costs: The potential benefits of these measures in the long term are a lower incidence of tooth decay, longer retention of teeth and prevention of fluorosis. The cost saving can be considerable for patients and insurers; however, implementation of some recommendations will be difficult, since the traditional preventive practices of dentists and dental hygienists are not easily changed.
Recommendations: There is good evidence that the following manoeuvres are effective in preventing dental caries: use of dentifrices containing fluoride, fluoridation of drinking water, fluoride supplements for patients in areas where there is a low level (0.3 ppm or less) of fluoride in the drinking water, professionally applied topical fluoride and the use of fluoride mouth rinses for patients with very active decay or at a high risk of dental caries and selective use of professionally applied fissure sealants on permanent molar teeth. There is poor evidence that the following manoeuvres are effective in preventing dental caries: professionally applied topical fluoride and the use of fluoride mouth rinses for patients with a low risk of caries, toothbrushing (without a dentifrice containing fluoride) and flossing, cleaning of teeth by a dentist or dental hygienist before topical application of fluoride or at a dental visit and dietary counselling for the general population. There is good evidence to recommend against the use of over-the-counter fluoride mouth rinses by the general population.
Validation: These guidelines are compatible with those of the US Preventive Services Task Force.
Sponsor: These guidelines were developed and endorsed by the task force, which is funded by Health Canada. Major funding was provided by the Faculty of Dentistry of the University of Toronto, Toronto, and the Faculty of Dentistry of Dalhousie University, Halifax.
[Table of Contents]
Dental caries (commonly known as tooth decay) is a localized, progressive demineralization of the hard tissues of the crown and root surfaces of teeth. The de-mineralization is caused by acids produced by bacteria, particularly Streptococcus mutans and possibly lactobacilli, that ferment dietary carbohydrates. This process occurs within dental plaque, a bacteria-laden gelatinous material that adheres to the surfaces of teeth. Dental caries is a dynamic process; periods of demineralization alternate with periods of remineralization.(1,2) If destruction exceeds repair, a preclinical, demineralized, subsurface carious lesion becomes a frank clinical cavity characterized by a breakdown of surface enamel and extension of the decay into the dentine.
During the last 15 years, significant reductions in the prevalence of dental caries have been achieved in Canada, largely as a result of the use of fluoride. Despite this improvement, caries remains a large problem for a significant proportion of the population. The costs to diagnose, prevent, treat and retreat dental disease, particularly dental caries, are considerable. Canadian dental care costs in 1989 were an estimated $3.1 billion, which is 2.4 times the level of such costs in 1980.(3)
The Canadian Task Force on the Periodic Health Examination wished to provide practising physicians and dentists with up-to-date, evidence-based recommendations for the prevention of dental caries. To provide the basis for these guidelines, recent findings about the diagnosis, epidemiologic features, socioeconomic impact and effectiveness of preventive interventions are described. Although many of the interventions discussed are not provided by physicians or allied health care professionals, the interventions provided by physicians and others to prevent dental decay (e.g., fluoride supplementation) must be evaluated in this broader contxReferral to dental services is also an option; therefore, we have provided information concerning which patients are at a high risk of dental caries and which dental services are effective. The clinical options considered were systemic fluoride administration, professionally applied fluoride, use of fluoride mouth rinses, fissure sealants, oral-hygiene practices, dietary practices, identification of groups of patients at a high risk, and early diagnosis and treatment. The effect of these options on the prevalence of dental caries and fluorosis, retention of teeth and cost were evaluated.
This review was based on the results of several MEDLINE searches for articles on dental caries published from January 1980 to December 1992. The values and methods of the task force were used to develop clinical practice guidelines.(4) Two consultants (D.W.L. and A.I.I.) reviewed the literature and provided a written report to all members of the task force. Consensus was then reached on the thoroughness of the review and the grading of the evidence and recommendations.
Although there are large international and regional differences, the incidence and prevalence of coronal dental caries has declined in industrialized countries over the past 20 years.(5) The prevalence in Canadian children is now 33% to 50% lower than it was 20 years ago, and many children have no tooth decay or fillings.(7) In the United States in 1986 and 1987, 50% of children 5 to 17 years of age had permanent teeth completely free of decay and restorations.(8) The rate of progression of carious lesions through tooth enamel and dentine has slowed as well.(6,9)
There have been small reductions in the number of decayed, missing and filled teeth and in the rate of edentulism (total tooth loss) in adults.(5) Recent reviews show that dental caries, not periodontal disease, is the primary cause of tooth loss in adults.(10,11) Indeed, a study published in 1987 showed more continuous coronal caries activity in younger and older adults than was previously believed.(12) The marked improvement in dental-caries status and in retention of teeth among children will eventually become evident in adults as these children grow up. However, there will be a transition period of about 40 years before improvements are evident in all age groups.(13) In older groups the common problems of secondary tooth decay around old fillings, the need for replacement of fillings and breakage of tooth cusps due to extensive fillings have led to a large treatment backlog.
Interest in root caries has increased as a result of longer retention of teeth and the aging of the population. Some authors believe that there will be more root caries in the future because of the increase in the number of retained teeth at risk of periodontal disease with gingival recession.(14) However, others suggest that, even if the absolute prevalence of periodontal recession increases as a result of an aging population, preventive exposure to fluoride will prevent root caries.(15) A secular increase in root caries seems to have occurred; however, the studies evaluating the incidence, prevalence and risk factors of root caries have methodologic problems.(16,17) In the few studies completed, annual incidence rates of 1.6 to 1.8 surfaces with root caries per 1000 surfaces at risk have been reported. A minority (30% to 40%) of the group studied bears the entire burden of root caries. There has been wide variation in the age ranges, the nature of the populations and the proportions of populations with at least one decayed or filled root lesion (21% to 83%) reported in prevalence studies.(16-18)
The extensive decline in the incidence of dental caries has not benefited all children equally. US data show that 20% to 25% of children -- the so-called "high-risk" children -- have high levels of tooth decay.(19) Two recent clinical trials that investigated children in Ontario at high risk of dental caries found levels of tooth decay similar to those reported years ago.(20,21) Such children 6 to 7 years of age had 11 or 12 decayed, missing or filled tooth surfaces per child on average, and those 10 to 11 years of age had 9 or 10 such surfaces per child on average.
Detailed reviews of the many risk factors and risk indicators for dental caries have been reported elsewhere.(22-24) Children and adults with certain medical problems are at a higher risk of dental caries than their peers. These problems include bulimia, Sjögren's syndrome, radiation therapy directed to the head or neck, chemotherapy, or prolonged use of drugs that reduce the flow of saliva.(25) People living in an institution and those with physical and mental disabilities are also at higher risk than others.(22-24)
Age,(24) socioeconomic disadvantage(23) and previous dental caries(24) are strongly linked with the incidence of dental caries. Although past research showed that eating sugar was a definite risk factor,(26,27) current research findings concerning the effect of contemporary dietary practices on dental caries have been equivocal.(23,28,29) However, this research does show that people with a high sugar intake and poor oral hygiene may be at high risk of dental caries.
No single salivary factor yet identified has good predictive values for dental caries, although salivary flow rate and buffering capacity may prove to be risk indicators.(24,25,30-32) The incidence of coronal dental caries is associated with the initial presence of Streptococcus mutans in dental plaque and with the presence of lactobacilli in later stages of caries.(30,31) Table 1 lists groups considered, from a clinical perspective, to be at a high risk of dental caries.
Nursing caries, also called baby-bottle tooth decay, is a specific form of severe decay that affects the primary teeth of infants in a very characteristic manner.(33) Nursing caries occurs rapidly and affects the upper, but not the lower, anterior primary teeth and some posterior teeth. The prevalence is particularly high in aboriginal populations,(34) but in the general population it is no higher than 5%.(33) Numerous case reports suggest that the main cause of this severe decay is exposure to almost any sugary liquid (including milk, formula, fruit juices and sweetened liquids) for long periods, such as occurs during nocturnal bottle feeding of babies.(33) In case-control studies the odds ratio for nursing caries from nocturnal bottle feeding is estimated at between 7 and 32.(35,36) However, owing to the design of these studies, the overall evidence for this association is weak.
Visual detection of advanced coronal decay, with subsequent histologic determination as the gold standard, has a sensitivity of 84% and a specificity of 78% for pit-and-fissure surfaces and predictive values of a positive test of 92% and of a negative test of 63% (unadjusted for current prevalence).(40) For the use of radiographs to diagnose small cavities between the teeth, a sensitivity of 98% and a specificity of 36% and unadjusted predictive values of a positive test of 97% and of a negative test of 53% have been reported.(41)
In view of the wide spectrum of risk indicators for caries, it is not surprising that various simple tests for susceptibility to dental caries involving single predictors(25,30,31) and, more recently, multiple predictors(17,23,42,43) have been developed. None of these methods has succeeded in predicting the risk of all types of caries for individual patients, although in prediction of caries on root surfaces results were more promising.(17,43)
In fact, the diagnosis of dental caries in clinical practice is idiosyncratic and plagued by considerable variation among practitioners.(44-46) Studies have shown variation among dentists in their development of plans for restorative care after examining the same group of patients(44) and in their interpretations and treatment decisions concerning dental caries when examining the same set of radiographs.(45) In a Scottish study in which 15 dentists examined 18 young adults, the probability of agreement between two dentists selected at random about filling a particular surface was only 0.4.(46) There was a fivefold difference in the cost of the planned treatment between two of the dentists.
Secondary prevention of dental caries involves the replacement of destroyed tooth tissue with various types of restorations to prevent further destruction. This aspect of prevention will not be discussed further, except to note that full restoration of incipient lesions should be discouraged in favour of small, noninvasive, resin restorations in pits and fissures or intensive primary prevention with fluoride to enhance remineralization of smooth tooth surfaces. Tooth restoration appears to lead to a lifelong cycle of replacement fillings, each of which is slightly larger than the one it replaces; this should be avoided if possible.(47)
In order to protect teeth, fluoride must be loosely bound and freely available in the oral environment. Free fluoride ions combine with the hydroxyapatite crystal of the tooth to form a complex that is more resistant to demineralization than the crystal alone. Fluoride ions also have a strong influence on the arrest and healing of early carious lesions by bonding with the calcium and phosphate ions lost from teeth after an acid attack.
Because of the widespread availability of fluorides, there is now concern about increases in the prevalence of fluorosis in the teeth of children, although such fluorosis is usually very mild.(52,53) Dental fluorosis is visible as soon as the tooth erupts and results from the incorporation of too much fluoride into the calcium hydroxyapatite crystals of enamel. This can be caused by exposure to higher concentrations of fluoride than the optimal level (0.7 to 1.2 ppm), which can occur when a child ingests fluoride supplements, toothpaste and fluoride from other sources. In mild cases of fluorosis the tooth appears to have white lines scattered irregularly on its surface. In more severe cases hydroxyapatite crystals may fail to form during enamel mineralization, which leaves voids or spaces inside the enamel; the teeth may have white areas or appear stained, eroded or pitted. In children, fluorosis appears most frequently as "snowcapping," a parchment-white-coloured area on the incisal or occlusal surface of the tooth that resembles the snow caps on mountains. By the time the physician or dentist recognizes fluorosis in the permanent teeth, it is too late to prevent its appearance on most of the other teeth, including those yet to erupt, because fluoride has already been incorporated into their enamel. Therefore, providing the appropriate amount of fluoride during the first 6 years of life is the best method to prevent both caries and fluorosis.
The observed increase in fluorosis has been attributed to inappropriate prescribing of fluoride supplements by dentists and physicians(54,55) or overzealous use of these supplements at the urging of parents or both.
To reduce the unnecessary risk of fluorosis, guidelines of the Canadian Workshop on the Evaluation of Current Recommendations Concerning Fluorides(56) recommended that the schedule for dietary fluoride supplementation be modified to prevent the condition (Table 2). These guidelines have not been evaluated in clinical practice but were officially sanctioned in 1993 by the Canadian Dental Association on the basis of expert opinion. They have not been adopted by other health care organizations.(50) Local health units should be consulted regarding appropriate supplement dosages.
Professionally applied topical fluoride, mainly acidulated phosphate fluoride (APF) gel, continues to be popular. It has proven to be efficacious on the basis of randomized controlled trials (RCTs) involving children, although there have been few trials of this agent involving a placebo control since 1980, the beginning of the era of the decline in the incidence of caries.(57)
There are three issues for consideration in the use of topical fluoride. First, several recent RCTs have shown that the traditional prophylaxis (cleaning) of the teeth before professional application of topical fluoride is not efficacious in reducing decay.(57) This prophylaxis takes up about two-thirds of the total time for the procedure; hence, topical fluoride application without prophylaxis is equally efficacious but less costly.
Second, the recommended frequency of professional application of topical fluoride -- biannual rather than annual -- is not as well studied as conventional wisdom would lead one to believe.(57) There is only one RCT, published in 1971, in which the use of a fluoride agent -- APF solution -- was tested annually and biannually.(58) The additional absolute savings, in terms of decayed, missing or filled tooth surfaces, of biannual over annual application was not clinically important, statistically significant or cost effective. Similarly, an RCT conducted in Ontario found no significant effect of biannual over annual applications, with or without prior prophylaxis, after 3 years of treatment.(21)
Third, several studies have shown that the retention and swallowing of fluoride, especially by young children, after professional application of topical fluoride is surprisingly high.(52) Thus, careful technique and the use of conservative amounts of fluoride gel are very important.
Today, costly professional topical application of fluoride cannot be recommended for most children, especially in communities with water fluoridation,(57) because the decline in the incidence of dental caries makes such treatment unnecessary. However, this form of fluoride therapy is recommended for patients with active decay, those at a high risk of caries, those undergoing radiation therapy directed to the head and neck, and older adults with root caries.(57)
Self-applied fluorides, such as the almost universally used fluoride dentifrices, are strongly recommended because of their ease of use, low cost and effectiveness in preventing coronal and root caries, as shown by RCTs.(57,59) The decline in the incidence of caries in developed countries during the past 15 to 20 years is invariably ascribed to the use of fluoride toothpastes. However, the concern about the increased incidence of mild fluorosis has prompted recommendations for more cautious and supervised use of fluoride dentifrices, particularly by young children.(52,56,60)
Although a daily fluoride mouth rinse containing 0.05% sodium fluoride and a weekly rinse containing 0.2% sodium fluoride were previously shown to be effective in school-based, supervised trials,(57) a more recent Canadian trial involving schoolchildren 9 to 11 years of age in communities with fluoridated and unfluoridated water showed no significant effect of mouth rinses.(61) In recent years, low-potency over-the-counter fluoride mouth rinses have been marketed, but there is insufficient data on their effect on caries.(60) None of these fluoride rinses is intended for children under 5 years of age.(57) As a result of the decline in the incidence of caries and the concerns about excessive ingestion of fluoride, fluoride mouth rinses are now recommended only for those at high risk of dental caries and those who do not regularly use a fluoride dentifrice.(62)
Since sugars are a cause of caries,1 selective counselling, limited to children at a high risk of caries, may still be indicated. Because of the risk of severe decay of infants' teeth,(33,35,36) the nocturnal or other prolonged use of baby bottles containing liquids other than water is not advised;(33) however, the effect of counselling on this practice has not been evaluated.
Oral-hygiene practices consist of plaque removal by toothbrushing and flossing and the professional prophylaxis that often precedes a periodic dental examination. There is no evidence that these measures, as ordinarily practised, lead to reductions in the incidence of car-ies.(23,25,67) Daily personal oral hygiene (toothbrushing and flossing) is recommended in the interests of good hygiene, because of its effect on the esthetic appearance of teeth and on gingival disease, and as a vehicle for the ap-plication of fluoride dentifrice, a proven caries preventative.
There is poor evidence to support daily brushing and flossing strictly to prevent caries (grade C recommendation);(23,67) however, brushing is essential for applying fluoride dentifrice to teeth, and brushing and flossing are recommended to prevent gingivitis.
There is good evidence from RCTs for the selective use of fissure sealants on the recently erupted permanent molars of children at a high risk of caries (grade A recommendation).(7,63,64)
There is poor evidence on which to evaluate counselling patients to change their diet(28,29,66) or to refrain from long-term use of baby bottles containing liquids other than water.(33)
Almost all of these recommendations differ from those in the task force's 1980 report.(68)
As a result of the changing epidemiologic patterns of dental caries and the need for efficiency in dental services, the use of dental-caries preventatives should be more selective and targeted to groups at a high risk of caries. It is impossible to estimate the benefit that would result from these recommendations, since such a benefit would be realized only after the long-term use of the preventive interventions. However, we believe that the recommended manoeuvres could reduce the incidence of dental caries by 20% to 50%. If fluoride is used appropriately, the prevalence of fluorosis should not be more than 10%, and any resulting fluorosis should be very mild.
The recommended actions for physicians and nurses listed in Table 4 are compatible with those issued by the US Preventive Services Task Force.69 The recommendations on fluoride use are identical to the guidelines from the Canadian Workshop on the Evaluation of Current Recommendations Concerning Fluorides.(56,70)
Major funding for this update was provided by Health Canada, the Faculty of Dentistry of the University of Toronto, Toronto, and the Faculty of Dentistry of Dalhousie University, Halifax.
Funding for the task force is provided by the Health Services and Promotion Branch, Health Canada, and by the National Health Research and Development Program (grants 6605-2702-57X and 6603-1375-57X).
We thank the following for reviewing the draft report: Drs. D. Christopher Clark, BS, DDS, MPH, associate professor, University of British Columbia, Vancouver; David W. Banting, DDS, DDPH, MSc, PhD, FRCDC, professor of community dentistry, University of Western Ontario, London, Ont.; David W. Johnston, BDS, MPH, chair and associate professor, Department of Community Dentistry, University of Western Ontario, London, Ont.; James L. Leake, DDS, DDPH, MSc, FRCDC, chair and professor, Department of Community Dentistry, University of Toronto, Toronto; and Wyatt R. Hume, BDS, PhD, DDSc, professor and chair, Department of Restorative Dentistry, University of California (San Francisco), San Francisco.
Options : Administration générale de fluorure, fluorure appliqué par un professionnel, utilisation des rince-bouche au fluorure, agents de scellement des puits et fissures, pratiques d’hygiène buccale, habitudes alimentaires, identification de groupes à risque élevé de carie dentaire et diagnostic et traitement précoces.
Résultats : Baisse de la prévalence des caries dentaires et de la fluorose, conservation de la dentition pendant plus longtemps et réduction des coûts de traitement.
Preuves : On a effectué plusieurs recherches dans MEDLINE pour y trouver des articles publiés entre janvier 1980 et décembre 1992, y compris des articles pertinents de revues de la littérature.
Valeurs : Les résultats cliniques pertinents ont été évalués et classés à l’aide des méthodes fondées sur la preuve et des valeurs du Groupe d’étude canadien sur l’examen médical périodique. On a formulé des recommandations sur chaque méthode de prévention des caries et accordé des valeurs élevées à la réduction de l’incidence des caries dentaires et à l’amélioration de la prévalence des dents sans carie.
Avantages, préjudices et coûts : Les avantages possibles que ces mesures offrent à long terme sont une baisse de l’incidence des caries dentaires, la conservation de la dentition pendant plus longtemps et la prévention de la fluorose. Les coûts peuvent diminuer considérablement pour les patients et les assureurs, mais certaines recommandations seront difficiles à mettre en oeuvre puisque les pratiques traditionnelles de prévention des dentistes et des hygiénistes dentaires sont difficiles à changer.
Recommandations : Les preuves qui indiquent que les interventions suivantes réussissent à prévenir la carie dentaire sont solides : utilisation de dentifrices au fluorure, fluoruration de l’eau potable, suppléments de fluorure à faible dose pour les patients dans les régions où l’eau potable contient peu de fluorure (0,3 ppm ou moins), application de fluorure topique par des professionnels et utilisation de rince-bouche au fluorure par les sujets atteints de carie très active ou à risque élevé de carie dentaire et application sélective d’agents de scellement sur les molaires permanentes par des professionnels. Les preuves qui indiquent que les interventions suivantes réussissent à prévenir la carie dentaire sont faibles : application de fluorure topique par des professionnels et utilisation de rince-bouche au fluorure par les sujets à faible risque de carie, brossage des dents (sans dentifrice au fluorure) et utilisation de la soie dentaire, nettoyage des dents par un dentiste ou une hygiéniste dentaire avant l’application topique de fluorure ou au cours d’une visite chez le dentiste et conseils en alimentation pour la population en général. Les preuves contre l’utilisation, par la population en général, des rince-bouche au fluorure en vente libre sont solides.
Validation : Ces lignes directrices sont compatibles avec celles du US Preventive Services Task Force.
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