A Contemporary Perspective on Dental Sealants
Changes in the prevalence and distribution of caries, the effectiveness of sealants, and guidelines for use are reviewed.
By Jayanth V. Kumar, DDS, MPH, and
Mark D. Siegel, DDS, MPH
 |
In spite of significant improvements in the oral health of Americans, dental caries still affects a majority of school-aged children. Its distribution is uneven, with a small proportion of the children experiencing a greater burden of the disease. In addition, caries in children's permanent teeth is predominantly a disease of the pits and fissures. The use of dental sealants has the potential to significantly reduce the disease burden. Although sealants are safe and effective, their use continues to be low. Efforts are needed to make sealants a covered benefit under all insurance plans and to encourage their appropriate use. This paper provides a review of the changes in the prevalence and distribution of dental caries, the effectiveness of sealants, and guidelines for the appropriate use of sealants in public health programs and private practice. |
Article copyright 1998 Journal of the California Dental Association.
Photographs copyright of the authors.
The oral health of Americans has never been better as evidenced by the
declining trends in oral diseases, notably dental caries in children.(1,2)
Edentulousness in the elderly has steadily declined, and most adults are
retaining their natural teeth.(3) A Michigan study showed how these disease
trends are reflected in the mix of services provided to an insured group.
While preventive services and periodontal care have increased, extractions
and restorative and prosthetic services have decreased.(4)
The improvement in oral health has been attributed to increased availability
of fluorides, improved oral hygiene, rising expectations of maintaining
a functional dentition, effective treatment, and improved restorative materials.1,2
All the news on oral health and health care, however, is not good. Reports
of difficulty for the uninsured, underinsured, and medically indigent groups
in accessing dental care; the disparity in oral health status between poor
and nonpoor; and the lack of coverage for dental services under most health
insurance plans are disconcerting. The lower survival rate of oral cancer
patients compared to similar cancers and the low utilization rate of dental
sealants are just two examples that illustrate how access to prevention
and early detection remains beyond the reach of many Americans.(5)
In spite of the difficulty in accessing dental care for some Americans,
impressive changes have occurred in the prevalence and distribution of
dental caries. Many studies show that caries in children's permanent teeth
is predominantly a disease of pits and fissures.(1,2,6-9) A national survey
conducted from 1988 to 1991 showed that among 5- to 17-year-old children,
56 percent and 32 percent of all decayed, missing, and filled surfaces
(DMFS) occurred on the occlusal and buccal or lingual surfaces, respectively
(Table 1). Although the pattern of caries was similar among different
racial and ethnic groups, the filled component of the DMFS index varied
by race in this survey (Table 2). Among blacks and Mexican-Americans,
less than 50 percent of the once decayed surfaces were treated.10 This
survey also showed that the distribution of caries in the population is
uneven, with 25 percent of the children aged 5 to 17 accounting for about
80 percent of the teeth attacked by caries in this age group.
| Table 1
Mean Number of Decayed, Missing, and Filled Permanent Tooth Surfaces (DMFS) by Surface for 5- to 17-Year-Old Children. National Health and Nutrition Examination Survey - Phase 1, 1988-1991. |
|||
| Age Groups (Years) | Occlusal DMFS | Buccolingual DMFS | Mesiodistal DMFS |
| All | 1.4 | 0.8 | 0.3 |
| 5-11 | 0.4 | 0.3 | 0.1 |
| 12-17 | 2.4 | 1.3 | 0.5 |
| Table 2
Mean Number of DMFS, and Proportion of Decayed, Missing, and Filled PermanentTooth Surfaces. National Health and Nutrition Health and Nutrition Examination Survey - Phase 1, 1998-1991. |
||||
| Age Groups | DMFS (SE*) | % D/DMFS | %F/DMFS | % M/DMFS |
| All | 2.5 (0.2) | 19.7 | 78.4 | 1.9 |
| 5-11 | 0.9 (0.1) | 27.9 | 70.8 | 1.3 |
| 12-17 | 4.4 (0.4) | 16.0 | 81.8 | 2.1 |
| Blacks (5-17) | 2.5 (0.2) | 37.7 | 57.7 | 4.6 |
| Mexican-Americans (5-17) | 2.7 (0.1) | 36.4 | 60.6 | 3.0 |
| *SE-standard error | ||||
Several studies have shown a shift in dental caries from children of high
socioeconomic status to those of low socioeconomic status.(2,6,11) Studies
conducted in the 1960s showed that caries was more frequent in high socioeconomic
status children.(2) However, now studies consistently show that poor children
have had more disease over their lifetimes and have more untreated disease.(2,5,11)
National surveys have also shown regional variation in caries prevalence.
The Pacific (California, Oregon, and Washington) region had one of the
highest caries levels, whereas the Southwest had the lowest. The regional
variation in the difference in caries prevalence between fluoridated
and nonfluoridated areas is also apparent in the national survey. For example,
the residents of Pacific region's fluoridated communities had DMFS scores
that were less than half of those living in the region's nonfluoridated
communities (mean DMFS of 1.42 vs. 3.61), a greater difference than in
any other region.(1) This variation has been attributed, in part, to the
proportion of the population covered by fluoridation. While 34 to 74 percent
of the population is covered by fluoridated water in other regions of the
country, only 19 percent of the population received fluoridated water in
the Pacific region.
In addition to the decline in caries and changes in its distribution, data
also indicate that the rate of lesion progression through the tooth has
slowed considerably.(12,13) The interval between caries initiation and
cavitation has lengthened, in part because of the increased availability
of fluoride and its ability to remineralize lesions. An important implication
of this slow progression is that placement of sealants on incipient lesions
reduces the risk, if any, of rapid progression and therefore provides ample
opportunity to monitor adequately and intervene should there be a need
for it.
Use of Sealants
Although sealants have been around for more than two decades, their
use has never been as widespread as that of other preventive measures.
Estimates of the prevalence of dental sealants in the 1980s ranged from
4 percent to 19 percent.(14) Data from a recent national health examination
survey show that the percent of children aged 8 and adolescents aged 14
having one or more dental sealants in permanent teeth increased to 20.9
percent and 28.2 percent, respectively. Blacks and Mexican-Americans, however,
are about one-third as likely to have sealed permanent molars as are white
children.(14) Although this is a significant increase when compared to
the 1986-87 national children's survey, where only 11 percent and 8 percent
of 8- and 14-year-olds had sealants, it falls short of the national objective
(50 percent by the year 2000) set by the U.S. Public Health Service.
In California, a survey of third- and 10th-grade schoolchildren concluded
that the percentage who received protective sealants on permanent molar
teeth also fell short of the national objective.(15) This study found a
wide disparity in sealant prevalence with respect to race, poverty, and
fluoridation status. It shows that only 10.4 percent of 8-year-old children
and 12.6 percent of 15-year-old adolescents had sealants.
Sealant Effectiveness
Dental sealants have been shown to be effective in caries prevention.(16,17)
Sealants are 100 percent effective in preventing pit and fissure caries
if they are completely retained. According to Weintraub, the median retention
rate based on 49 studies was 92 percent after one year and 67 percent after
five years. Wendt and Koch reported 80 percent retention after eight years.(18)
More recently, Selwitz and colleagues reported that the overall proportion
of sealants retained on the occlusal surfaces of first molars after an
average of two years was 92 percent.(19) In a public health sealant program
in New York state, sealant retention rates on first molars over four years
varied from a low of 64.5 percent on the distolingual groove of maxillary
first molar to a high of 83.9 percent on the occlusal surface of mandibular
first molar. Factors such as the eruption status, pit and fissure morphology,
tooth and surface type, clinical setting, operators' ability, age of children,
and type of sealants are all known to contribute to this variation in reported
retention rates. Overall, retention rates on distolingual grooves of upper
first molars and buccal pits of lower first molars appear to be lower compared
to other sites. The most common reason for sealant failure is salivary
contamination, usually due to inadequate isolation.
The effectiveness of sealants can be judged from the rate of caries or
restorations on sealed, as compared with unsealed, pit and fissured surfaces.
Simonsen reported that the percent of sound and sealed first permanent
molars that became decayed or filled after 10 years was 21.7, compared
to 68.3 for unsealed teeth.(20) Recently, Heller and colleagues reported
that the odds of unsealed tooth surfaces becoming carious after five years
was 4.2 times greater than for sealed surfaces.(21)
Cost-Effectiveness of Sealants
While the effectiveness of sealants has been shown repeatedly, cost
savings from sealant use has been questioned.(6,7,17,22) The concern expressed
by many researchers is that if fewer teeth are becoming carious, the cost
of providing sealants to all teeth in all children far exceeds the cost
of providing treatment. For example, Leverett and colleagues concluded
that five sealants would have to be placed on sound surfaces and maintained
for four years to prevent one carious lesion.(22) In a study of 7- to 17-year-old
children in Nelson County, Va., an average of eight sealants was applied
per individual to prevent one tooth surface from becoming decayed or filled.(19)
Even on the occlusal surfaces of first molars, a highly caries-susceptible
surface, an average of 5.4 sealants had to be placed to save one surface
from decay. Heller and colleagues found that initially sound surfaces did
not benefit greatly from sealants over a period of five years compared
with sealing initially incipient carious surfaces. For incipient lesions,
the five-year decay rate was 10.8 percent for sealed surfaces and 51.8
percent for unsealed surfaces. However, for initially sound surfaces, the
five-year decay rate was 8.1 percent and 12.5 percent for sealed and unsealed
surfaces, respectively.(21) These results should be viewed with caution
because populations having higher levels of caries attack will show more
favorable results. Several authors recommend targeting resources to individuals
at higher risk for decay and to the most caries-prone tooth surfaces to
reduce overtreatment.(7-9,22) Such recommendations have included selection
of teeth based on morphology and history of caries, and restricting the
sealants to teeth with incipient lesions.
Risk Assessment
It is generally acknowledged that caries is unevenly distributed in
the population and that certain individuals possess characteristics that
put them at higher risk for the disease. Caries risk assessment is a process
that can identify these individuals. Most population-based studies indicate
that 20 percent to 30 percent of the children have more than 75 percent
of the disease burden. Many researchers have pointed out that such a shift
in caries distribution may have made the routine application of preventive
measures for all children of questionable value. Stamm and colleagues suggested
that intense preventive measures could be applied more selectively if high-risk
individuals were identified prior to the onset of the disease.23 Risk factors,
such as the pit and fissure morphology, exposure to carbohydrates, and
presence of Streptococcus mutans can be modified with current preventive
measures.
The need to target appropriate preventive measures on an individual basis
assumes greater importance because of the proliferation of alternatives
to fee-for-service reimbursement in dental care delivery. Unlike fee-for-service
programs, capitation-based reimbursements do not provide financial incentives
for rendering services that are likely to be ineffective or unnecessary.
Therefore, under capitation programs, it may be more beneficial to categorize
children based on their risk and provide appropriate preventive measures
rather than the traditional practice of routine six-month recall, prophylaxis,
two bitewing X-rays, and topical fluoride treatments. As a result, fewer
children will get intensive preventive regimens, and many more will not
get clinical preventive services.
Previous studies of risk assessment suggest that the current methods incorporating
demographic, behavioral, microbiologic, and clinical factors cannot always
predict caries accurately.(9,12,24) Practical problems make it difficult
to sample bacteria, assess dietary habits, and estimate the composition
of saliva. For example, an estimation of bacterial count based on one tooth
site or saliva at a single point in time may not be indicative of the true
risk imposed. The multifactorial nature of the disease coupled with the
interaction among various protective and risk factors make caries prediction
very difficult. According to Rozier, only about 50 percent of children
are correctly identified when risk assessment methods indicate a positive
result. For those with a negative result, about 80 percent are correctly
identified.(24) Although these methods are not perfect, studies have shown
that an experienced clinician can predict caries reasonably well in children.(25)
This is not surprising because a clinician can take into account a patients'
history; their oral hygiene; clinical findings, such as pit and fissure
morphology; and the use of dental services to determine the risk for caries.
The American Dental Association's guide Caries Diagnosis and Risk Assessment
also presents a practical approach for risk assessment (Figure 1).(26)
| Figure 1
Caries Risk Classification Guidelines |
||
| Risk Category | Child/Adolescent | Adult |
| Low | No caries lesions in last year
Coalesced or sealed pits and fissures Good oral hygiene Appropriate fluoride use Regular dental visits |
No carious lesions in last three years
Adequately restored surfaces Good oral hygiene Regular dental visits |
| Moderate | One carious lesion in last year
Deep pits and fissures Fair oral hygiene Inadequate fluoride White spots and/or interproximal radiolucencies Irregular dental visits Orthodontic treamtnet |
One carious lesion in last three years
Exposed roots Fair oral hygiene White spot and/or interproximal radiolucencies Irregular dental visits Orthodontic treatment |
| High | > 2 carious lesions in last year
Elevated mutans streptococci count Deep pits and fissures No/little systemic and topical fluoride exposure Poor oral hygiene Frequent sugar intake Irregular dental visits Inadequate saliva flow Inappropriate bottle feeding or nursing (infants) |
> 2 carious lesions in last three years
Past root caries; or large number of exposed roots Elevated mutans streptococci count Deep pits and fissures Poor oral hygiene Frequent sugar intake Inadequate use of topical fluoride Irregular dental visits Inadequate saliva flow |
| Source: ADA Council on Access, Prevention and Interpersonal Relation. JADA, 126:7s:195. Reprinted by permission of ADA Publishing Co., Inc. | ||
Guidelines for Sealant Use
Several guidelines were developed in the 1980s to help dentists select
appropriate teeth for sealants. The American Dental Association's Council
on Dental Research prepared a report to provide standards for third-party
insurance carriers for reimbursement of dental sealants.(27) The Massachusetts
Department of Health published the monograph Preventing Pit and Fissure
Caries: A Guide to Sealant Use in 1986.(8) Additional data on distribution
of caries, slower progression of caries, ubiquitous presence of fluoride,
availability of techniques to manage caries conservatively, cost-effectiveness
of sealants, and improvement in risk assessment methods prompted a reconsideration
of recommendations at the Workshop on Guidelines for Sealant Use, held
in Albany, N.Y., in 1994.(28) The scientific basis for these recommendations
for targeting communities, individuals and teeth (Figure 2) is that
differences in caries risk exist among individuals and among teeth, and
it is possible to incorporate prediction methods in private practice and
public health programs.
Although these methods are not perfect, the ability
to predict caries risk is sufficient to warrant the use of targeting principals.
The workshop participants concluded that:
- Pit and fissure caries occurrence is high, and the risk continues through
adolescence;
- Sealants are effective in preventing pit and fissure caries and arresting
caries progression;
- Sealant use requires meticulous application technique, particularly moisture
control;
- Whenever possible, sealant retention should be checked and teeth should
be resealed, if necessary; and
- To be cost-effective, sealants should be selectively provided to individuals and teeth at risk for disease.
Many states have initiated school-based sealant programs to extend the benefits of sealants, usually to children from low-income families, who generally are episodic users of primary dental care services. The objective of these programs is to prevent and control dental caries so that it becomes a manageable problem. These programs can provide a valuable preventive service, even if they don't provide a full range of diagnostic and treatment options.
Many community-based sealant programs have identified sealants as the treatment modality that will realize maximum benefits. Generally, communities and schools with greatest needs are identified. For this purpose, epidemiologic surveys provide the best possible data. However, such data are not always available. Therefore, proxy measures such as census data, percent of the children on free school lunch programs (which is a reflection of poverty level), dentist-to-population ratio, and reports from schools and observations made in other dental initiatives are used in determining the need for dental sealant programs.
Once the schools or other specific populations are identified, the use sealants may be targeted further. In the most common model, where sealants are provided in schools, selected grades are targeted. Most commonly, grades 2, 3, 6 and 7 are targeted because sealant placement on sufficiently erupted first and second molars can best be accomplished and followed-up. Alternately, some programs target all grades but limit the application of sealants to selected groups of children. The selection of these children is based on an assessment of risk at the aggregate level. For example, children of low socioeconomic families or Medicaid recipients may be targeted. To maximize resources, sealants may be provided to selected children and selected teeth.
In a school-based or school-linked public health program, the objective is to provide maximum benefits at the lowest possible cost; whereas in a private office-based program, the objective is to maintain a caries-free status. Although these objectives appear to be different, some general guidelines outlined at the Workshop on Guidelines for Sealant Use can be incorporated in both public health programs and private practice to accomplish the ultimate outcome of maintaining optimal oral health.(28) These guidelines are summarized here:
* Assess individuals' risk for caries. Although the ability to predict who will get caries is not completely accurate, certain factors are believed to be associated with risk for caries. These factors are past caries experience in primary or permanent dentition. In addition, considerations such as previous dental care, use of fluorides, frequency and adequacy of brushing and flossing, frequency of sugar intake, certain medications (e.g., antisialagogues and sweetened syrups), and medical conditions that result in xerostomia are also believed to increase the risk for caries.
* Assess risk of individual teeth. The most caries-susceptible permanent teeth are first and second molars. While occlusal surfaces are more prone to caries, buccal pits and lingual grooves are also at substantial risk and, therefore, suitable for sealant placement. Primary molars, premolars, and permanent maxillary incisors may be selected if the profile shows high risk. In general, level of caries activity, pit and fissure morphology, caries pattern, and the ability to isolate the teeth adequately determine the selection of teeth. The occurrence of one or more lesions per year is an indication of high susceptibility to caries. Figure 2 shows the steps involved.
* Evaluate pit and fissure surfaces for sealant application. All surfaces that possess deep pits and/or fissures should be sealed provided that these surfaces can be adequately isolated. Teeth with shallow pits and well-coalesced grooves are not likely to decay in low-risk individuals. Studies have shown that the greatest benefit is realized when teeth with incipient lesions are arrested by sealing them. Sometimes sealants can be placed even on those teeth with proximal lesions that can be independently managed. A pit and fissure lesion that has extended into the dentin should have the caries removed conservatively and restored. This treatment may include the use of sealants, as in a preventive resin restoration.
Because a majority of children in school-based programs or other public health programs do not use dental services on a regular basis, some modifications may be recommended. Sealants may be applied more liberally and, therefore, to a greater proportion of sound teeth and teeth with questionable caries lesions than would likely be sealed in a private office. Based on a review of the effect of sealants on dental caries, Swift concluded that the dentists' fear of sealing caries inadvertently is unfounded and should no longer be a concern.(29) Also, decisions in school programs are based on clinical examinations without the aid of radiographs, possibly resulting in caries diagnosis criteria that differ from an office-based approach. Parents must be made aware that a school-based program is not a substitute for a regular visit to a dentist. In reality, however, many or most children seen in school sealant programs would not routinely visit a private dental office. Similarly, practitioners should have an understanding of caries epidemiology, risk assessment concepts, and sealant promotion strategies.
Conclusion
A significant decrease in dental caries has occurred in the United States. Although sealants can contribute toward further improvement in oral health, their use remains relatively low. Several approaches have been adopted in the United States to promote sealant use. Community programs, most often through schools, have provided direct service by applying sealants to children's teeth. The development of public policies that foster sealant use through expansion of benefits is an effective method for increasing sealant use. For example, through the efforts of private dentists and public health officials, Medicaid programs in 49 states cover sealants as a benefit. Educational programs have been directed at the public, labor organizations, individuals responsible for administering health benefit plans, and patients in dental offices. These efforts seek to make sealants a covered benefit under all insurance plans and to encourage their appropriate use in dental practice.
Authors
Jayanth V. Kumar, DDS, MPH, is assistant director of the Bureau of
Dental Health for the New York State Department of Health and is an associate
professor in the School of Public Health at the University at Albany.
Mark D. Siegal, DDS, MPH, is chief of the Bureau of Oral Health Services
for the Ohio Department of Health.
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To request a printed copy of this article, please contact/Jayanth V. Kumar,
DDS, MPH, Bureau of Dental Health, New York State Department of Health,
ESP Tower Building, Albany, NY 12237-0619
