Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.
Overview
In 1979, the Canadian Task Force on the Periodic
Health Examination using the evidence then available made recommendations
concerning the prevention of dental caries.< 1> Since then, significant
reductions in the prevalence of dental caries have occurred in Canada,
and we have new understanding of its epidemiology, diagnosis, risk factors
and prevention. Despite this improving picture and the accrued benefits
of past, largely fluoride-related preventive efforts, dental caries remains
a large problem for a significant proportion of the population, a potentially
increasing problem for an aging population retaining more teeth and, surprisingly,
in view of the overall decreased caries prevalence, a growing major cost
problem for Canadians and those who insure their dental care.
In 1989 the U.S. Preventive Services Task Force published guidelines for the prevention of dental caries<2> and a more recent Canadian publication has provided more specific preventive guidelines that are similar to those of the U.S. Task Force.<3>
Burden of Suffering
Dental caries (decay) is ubiquitous and is one
of the most prevalent infectious diseases of man. It is a localized, progressive
demineralization of the hard tissues of the crown (coronal enamel, dentine)
and root (cementum, dentine) surfaces of teeth. The demineralization is
caused by acids produced by bacteria, particularly mutans Streptococci
and possibly lactobacilli, that ferment dietary carbohydrates. This occurs
within a bacteria-laden gelatinous material called dental plaque that adheres
to tooth surfaces and becomes colonized by bacteria. Thus, caries results
from the interplay of three main factors over time: dietary carbohydrates,
cariogenic bacteria within dental plaque, and susceptible hard tooth surfaces.
Dental caries is a dynamic process since periods of demineralization alternate
with periods of remineralization through the action of fluoride, calcium
and phosphorous contained in oral fluids.<4>
Dental caries is age-related. Prevalence begins soon after tooth eruption in susceptible children and increases with age. Although current Canadian data are lacking, older data when dental caries were more prevalent suggest that caries incidence had three peaks: at about age 7 years for coronal decay of the primary dentition; at about age 14 years for coronal decay of the permanent dentition; and, for root surface decay, incidence began at about age 30-40 years with steady increases thereafter.
The different morphology of the pit-and-fissure surfaces of teeth makes them more susceptible to decay than the smooth surfaces. Thus, it is no surprise to find that the posterior molar and premolar teeth that have pit and fissure surfaces are more susceptible than the anterior teeth. Based on epidemiologic studies, the pit-and-fissure occlusal (biting) surfaces of molar teeth usually decay within three years of eruption or not at all.<5,6>
Although great international and regional intranational differences exist, the incidence and prevalence of coronal dental caries have declined in the industrialized countries over the past 20 years.<7> This change has been well documented for children and adolescents. Canadian children now have 33-50% lower dental caries prevalence and many children have experienced no decay or fillings at all.<6> In the U.S. in 1986-87, 50% of 5-17 year old children were completely free of decay and of restorations in their permanent teeth.<8> There has also been a shift in the types of surfaces displaying decay or fillings. Now an even greater proportion of childrens’ decay (75-80%) occurs on pit-and-fissure surfaces.<6,7>
In adults, there have been small reductions in the number of decayed, missing and filled teeth and in the rate of edentulism (total tooth loss).<7> In dentate adults, the decline in missing teeth has been more substantial.<9> While it is believed that the marked improvement in dental caries status and greater tooth retention experienced by children will eventually be evident in adults, a long transition period of about 40 years will be required before improvement is evident in all adult age groups. Longer tooth retention and aging of the population have combined to increase interest in root caries. Because of inconsistencies in studies, estimates of the incidence, prevalence and risk factors associated with root caries are problematic. A secular increase in root caries has, however, occurred. In the few studies completed, annual incidence rates of 1.6-1.8 surfaces per 1,000 surfaces at risk have been reported along with the observation that only a minority (30-40%) of the group studied bear the entire burden of root caries attack. Prevalence surveys have revealed wide variations in the percent displaying at least one decayed or filled root lesion (21-83%).
The extensive decline in dental caries has not benefited all children equally. U.S. data reveal that 20-25% of children still have high decay levels – the so-called high-risk children. Adults not yet benefiting from this decline still have decay and fillings characteristic of a previous era. Secondary decay around old fillings, replacement fillings and breakage of tooth cusps due to extensive fillings are commonplace in this age group and represent a large treatment backlog.
Children and adults with special medical problems are at higher risk for dental caries. These include bulimics, those with Sj ¨ ogren’s syndrome, and those receiving therapeutic head and neck radiation, chemotherapy, or prolonged treatment with drugs that reduce salivary flow.<10> Institutionalized and physically and mentally disabled persons are also at higher risk for dental caries.
The financial burden of diagnosing, preventing, treating and re-treating dental disease, particularly dental caries, is great. Canadian dental care costs in 1989 were estimated at $3.1 billion, higher than many medical conditions.<11> This represents a tripling of dental care costs since 1979.
Detailed reviews of the many risk factors and risk indicators for dental caries have been reported elsewhere.<10,12,13> Age, socioeconomic status and past dental caries are strongly linked with dental caries incidence; oral hygiene as practised by most people is not strongly related to dental caries occurrence. However, because of the impact on esthetics and gingival disease and, as a vehicle for self-application of fluoride dentifrice, regular oral hygiene practices are recommended. Although past research indicated that sugar was a definite risk factor, current research findings about the effect of contemporary dietary practices on dental caries have given equivocal results except possibly for those at high risk because of high sugar intake and poor oral hygiene.
Maneuver
Traditionally, the clinical detection of carious
lesions on tooth crowns has involved the use of a sharp explorer, a viewing
mirror, an artificial light source and air-drying of tooth surfaces to
improve visibility. This visual and tactile approach is often supplemented
by the use of selected radiographs to help in the diagnosis of small (incipient)
lesions on the hidden surfaces between adjacent teeth. The early clinical
detection of incipient carious lesions has attracted increased interest
recently because of the possibility that primary preventive procedures
(e.g. topical fluorides) used by patients or by dental personnel may enhance
remineralization and even arrest dental decay.
The validity of visual detection of frank (more advanced) coronal decay using subsequent histological determination as the "gold standard", is represented by sensitivity and specificity values ranging between 0.78 and 0.84 and positive and negative predictive values of 0.63 to 0.92 (unadjusted for current prevalence).<3> Using radiographs for the diagnosis of caries between the teeth, sensitivities and specificities of 0.36 to 0.98 and (unadjusted) predictive values of 0.53 and 0.97 have been reported.<3>
Diagnosis of dental caries and treatment planning in clinical practice is idiosyncratic and plagued with considerable variation among dentists.<14,15> This has been demonstrated when the same group of patients and the same set of radiographs were examined.
Effectiveness of Prevention and
Treatment
Four types of primary prevention are reviewed:
fluorides; fissure sealants; dietary counselling; and oral hygiene.
Systemic Fluorides
Despite the apparent reduction in effectiveness
of water fluoridation due to declining caries levels (from about 50% reduction
in decay to 20-40%), fluoridation of the water supply remains the single
most effective, equitable and efficient means of preventing coronal and
root dental caries.<16> The impact of water fluoridation on coronal
decay in children, adolescents and adults has been studied in numerous
community trials and economic evaluations and the impact on root caries
has been evaluated in case-control studies. In areas having less than optimal
F (0.7-1.2 ppm) in their water supplies, prescription of fluoride supplements
is recommended, although compliance may be difficult.<17>
Because of the widespread availability of fluorides (in dentifrices, water, vitamin supplements, manufactured beverages and food), there is now concern about increases in the prevalence of (usually) very mild fluorosis in children’s teeth. Although mild fluorosis is usually neither unsightly nor easily visible, it is, nevertheless, evidence of excess fluoride intake.
A principal reason for the observed increase in fluorosis appears to be inappropriate prescribing of systemic fluoride supplements by dentists and physicians<18> and/or overzealous use of these supplements by parents for their children. The currently recommended supplemental fluoride dose schedule, adjusted for the child’s age and current fluoride content of water has been published elsewhere<3> as has a 1992 Canadian modification.<19> These modifications to avoid fluorosis suggest lower intakes of fluoride supplements because of increased use of fluoride toothpastes and ingestion of other food and beverage sources of systemic (and topical) fluoride that were not widely available when current guidelines were formulated.
Professionally-Applied Topical Fluorides
These agents, e.g., acidulated phosphate F gel
in trays, have been proven efficacious in randomized clinical trials in
children, though there have been few trials since 1980, the era of decline
in caries incidence.<20> It has now been established that there is no
need for a prophylaxis (cleaning) of the teeth prior to the application
of a topical fluoride<20> but similar evidence for biannual rather than
annual applications is lacking.
Today, costly professionally-applied topical fluoride cannot be recommended for use with most children in communities with water fluoridation<20> or, indeed, for most children generally because of the dental caries decline. However, this form of fluoride therapy is recommended for persons with active decay and at high risk, for those undergoing head and neck radiation therapy and for older adults experiencing root caries.<20>
Self-Applied Fluorides
These include the widely used fluoride dentifrices
that are strongly recommended because of their ease of use, low cost and
effectiveness on coronal and root caries prevention based on randomized
clinical trials.<20,21> The primary reason for the caries decline in
developed countries over the past 15-20 years is invariably ascribed to
fluoride dentifrices. However, concerns about a possible increase in mild
tooth fluorosis have prompted recommendations to use less dentifrice and
supervise the toothbrushing of young children.<19>
Fluoride mouth rinses were recommended a few years ago for general use. However, because of the decline in caries and concerns about excess fluoride ingestion, they are now recommended only for those at high risk to dental caries and for those not regularly using a fluoride dentifrice.<22> None of these rinses are intended for use in children under age 5.
Fissure Sealants
These are resins applied by dental personnel
to the pit-and-fissure surfaces of posterior teeth. They have been extensively
tested since 1979 in randomized clinical trials and have proven to be effective
in reducing this most common form of surface decay.<6,23> Because of
their high cost, the general decline in decay and differential tendencies
for certain fissures to decay, sealants should be applied selectively to
high risk patients and to permanent molars only, within 2-3 years after
tooth eruption.
Dietary Counselling
Encouragement to reduce sucrose intake and use
dentally ‘safe’ substitutes may be less important now for the majority
of persons. Two recent longitudinal (cohort) dietary studies revealed that
dental caries incidence was low among study children despite their high
sugar consumption.<24> In one study,<24> the only apparent etiologic
role of sugar was related to decay of smooth surfaces between the teeth;
however, this type of surface decay has rapidly declined in children recently.
Thus, routine dietary counselling today may be misguided. As well, the
effectiveness of dental counselling in inducing behaviour change is suspect.<25>
Since sugars are one of the etiologic factors in the caries process,<4>
selective counselling limited to high-risk children may still be indicated.
Similarly, because of the high risk of severe decay to infants’ teeth due
to this practice, the majority of studies do not advise the nocturnal or
other prolonged use of baby bottles containing liquids other than water.<26,27>
Oral Hygiene
Oral hygiene procedures consist of personal plaque
removal by toothbrushing and/or flossing as well as the professional prophylaxis
that often precedes a periodic dental examination. As ordinarily practised,
in neither case is there evidence that these lead to caries reductions.<12,28>
Daily personal oral hygiene (toothbrushing and flossing) is recommended
in the interest of good hygiene and for the control of gingival disease.
Toothbrushing is also required for the self-application of fluoride dentifrice,
a proven caries preventive.
Recommendations of Others
The U.S. Preventive Services Task Force<2>
has published recommendations for dental caries prevention (which are currently
being reviewed), as have the Department of National Health and Welfare<6>
(now Health Canada) and others.<16,20,22>
Conclusions and Recommendations
Lower dental caries prevalence and the need for
efficiency in the provision of preventive and therapeutic dental services
require selective use of dental caries preventives and targeting of services
toward persons at greatest risk. The following recommendations are based
on a review of the available evidence.
There is good evidence of effectiveness of the following measures in preventing dental caries (A Recommendation):
Evidence
Using the results of a literature search from
1980 to 1992 and significant review articles, relevant clinical findings
were evaluated and categorized using the levels of evidence developed by
the Task Force. This review was initiated in June 1992 and the recommendations
finalized by the Task Force in September 1993. A more detailed review with
a complete reference list is available.<3>
Acknowledgements
The authors are grateful to the following persons
who reviewed the earlier publication<3> on which this chapter is based:
D. Christopher Clark, BS, DDS, MPH, Associate Professor, University of
British Columbia, Vancouver, BC; Dr David W. Banting, DDS, DDPH, MSc, PhD,
FRCDC, Professor of Community Dentistry, University of Western Ontario,
London, Ontario; Dr. David W. Johnston, BDS, MPH, Chair and Associate Professor,
Department of Community Dentistry, University of Western Ontario, London,
Ontario; Dr. James L. Leake, DDS, DDPH, MSc, FRCDC, Chair and Professor,
Department of Community Dentistry, University of Toronto, Toronto, Ontario;
and Dr. Wyatt R. Hume, BDS, PhD, DDSc, Professor and Chair, Department
of Restorative Dentistry, University of California, San Francisco, San
Francisco, CA, USA.
Full Citation
Lewis DW and Ismail AI. Prevention of dental
caries. In: Canadian Task Force on the Periodic Health Examination. Canadian
Guide to Clinical Preventive Health Care. Ottawa: Health Canada,
1994; 408-17.