PREVENTION V

“DENTAL (PIT AND FISSURE) SEALANTS”

HISTORY

• The concept of sealing the fissures of teeth is over 100 years old. In 1895, Wilson, described in Dental Digest the use of oxyphosphate cement to seal fissures.

• Contemporary pit and fissure sealants were introduced into clinical dentistry in 1967 by Michael Buonocore of the Eastman Dental Center, Rochester. • Dr. Buonocore is credited with developing the field of adhesive dentistry through his introduction of the concept of acid etching of tooth enamel, and his documentation of the ability of resin materials to ‘adhere’ to such etched enamel surfaces. • The effectiveness of pit and fissure sealants as a preventive tool was recognized with provisional approval by the American Dental Association Council on Dental Therapeutics in 1971; full approval came in 1976.

• Since then the use of pit and fissure sealants, now generally referred to as dental sealants, has increased steadily.

SEALANT USAGE

• Surveys show an increase in sealant use among dentists from 38% in 1974 to as high as 90-95% of dentists in recent surveys.

• The U.S. Public Health Services goal for “Healthy People 2000” called for at least 50% of children 8-14 to have sealants placed. • Although no studies of sealant prevalence have been completed since 2000, it is thought that the prevalence of use will fall far below this goal.

• The prevalence of sealant usage in eight year olds grew from 7% to 15% from 1986 to the early 90s; during the same time period the percentage of fourteen year olds with sealants grew from 8% to 35%. When all school aged children are included, 18.5% had one or more sealed teeth in 1991.

CARIES PREVALENCE

• As we have discussed, there has been a significant decline in caries prevalence among school aged children in the past 20 30 years.

• Recall that the mean DMFS for school children in 1980 was 4.77, and had declined to 3.07 in 1986; a 36% reduction.

• 50% of school children were caries free in 1986, versus 37% in 1980.

COMPARISON OF AGE-SPECIFIC MEAN DMFS SCORES: 1980,1987

COMPARISON OF AGE-SPECIFIC PERCENT OF CARIES FREE CHILDREN: 1980,1987

RELATIVE DISTRIBUTION OF CARIES

• Not only has there been a change in the number of tooth surfaces affected by dental caries, but there has been a change in the relative distribution, or pattern, of caries on different tooth surfaces.

• There has been a greater percentage reduction for smooth surface caries (mesial and distal surfaces) compared to pit and fissure caries.

• Overall, 88% of the caries in school children occurs in pits and fissures, and only 12% on the proximal surfaces.

• This differential is related to the more significant impact of fluorides on smooth surfaces in reducing enamel solubility; and serves to underscore the imperative of dental sealants in a comprehensive program of prevention.

DISTRIBUTION OF DENTAL CARIES BY TOOTH SURFACE TYPE OF CHILDREN

TOOTH SURFACE ATTACK RATES IN PERMANENT TEETH BY SURFACE

PRINCIPLES UNDERLYING SEALANT USE

• Prevention of dental caries is preferable to treatment; sound, nondiseased teeth are to be more highly valued than adequately restored teeth.

• For equivalent outcomes, the least invasive approach, using the simplest intervention for managing dental caries is preferred.

• Minimizing the cost of preventing or controlling pit and fissure caries is desirable.

• Strategies for sealant use may vary between individual care and community-based programs.

SCIENTIFIC FACTS RELATED TO SEALANT USE

• Sealants have been demonstrated to be a safe and effective long-term method to prevent pit and fissure caries.

• Pit and fissure caries attack begins in childhood and continues through adolescence and into adulthood.

• In addition to preventing carious lesions, sealants can arrest caries progression.

• Effective sealant use requires meticulous attention to detail in application technique, particularly moisture control. Sealant retention should be checked within one year of application.

RISK ASSESSMENT IN TREATMENT PLANNING FOR SEALANTS

• Determination of the need for sealants begins with an assessment of the individuals risk for dental caries, as well as an assessment of the risk of the individual tooth.

• Factors contributing to individual risk include: – caries history – previous dental care – use of preventive practices – dietary habits • Factors to evaluate when considering individual teeth include: – individual’s risk for developing caries – pit and fissure morphology – caries pattern – status of the proximal surface of the tooth in question.

TREATMENT DECISION MAKING

• Studies suggest that the first and second permanent molars are at the greatest risk for pit and fissure caries; premolars are at significantly less risk.

• Primary teeth have an aprismatic layer of enamel and do not etch in the same manner as permanent teeth, consequently sealant retention is not as great on primary teeth. Additionally, the grooves of primary teeth tend to be well coalesced in comparison to permanent teeth.

• In general, we do not seal primary teeth.

• The cost-benefit effectiveness is greatest in sealing first and second permanent molars, and they should be given preferential treatment to premolars in application of sealants.

• Sealants are not necessarily indicated for permanent molars with well-coalesced grooves and no history of dental caries. • Indiscriminate sealing of teeth with low risk of caries reduces the cost effectiveness of sealants.

EFFICACY OF SEALANTS

• Sealants are effective as long as they remain intact. With complete retention sealed surfaces are virtually impervious to decay.

• Therefore, the effectiveness of sealants in preventing decay is measured by the retention of the sealant.

• However, there is some evidence that caries resistance is imparted by the presence of the resin “tags” in the etched microporosities. If true, the bulk of the sealant could be lost and if the resin tags remain intact, caries prevention will be effected.

VARIABLES AFFECTING SEALANT RETENTION

• Position of the teeth in the mouth – better sealant retention in mandibular versus maxillary arch--???

• Skill of operator – more skillful and experienced operators produce better sealant retention • Eruption status of the tooth – the younger the child, the more difficult to maintain a dry field due to the eruption status of the teeth; partially erupted molars are difficult to isolate.

• Patient Cooperation – children who present problems with cooperation make gaining and maintaining a dry field more difficult.

SEALANT RETENTION

• A compilation and summary of over 75 studies of sealant retention indicates:

– 94% of sealants were intact after one year – 83% of sealants were intact two years after placement.

– 67% were intact five years after placement.

– 57% were intact after ten years.

UPDATING TECHINQUE:

MATERIALS

• There is a wide variety of sealant materials from which to choose.

• Sealants are often classified by their method of polymerization, either autopolymerizing (chemically cured), or visible light-cured sealants; they are also classified by whether they are ‘filled’ resins, or ‘unfilled’ resins--though increasingly the market is dominated by filled resins. • Numerous studies have compared bond strengths and retention rates between the two and found they offer comparable results.

UPDATING TECHNIQUE:

CLEANING THE FISSURE

• Prior to acid etching the enamel, it is important to be sure that the tooth surface and fissure areas are free of gross plaque that might interfere with the etching process.

• Historically, it was recommended that this be done with a prophylaxis cup or bristle brush and pumice.

• Recent studies have shown that cleaning the tooth with a pumice prophylaxis does not significantly increase bond strength.

• Current recommendation is to run an explorer through the fissures and rinse forcefully with water; or, brush the fissures thoroughly with a tooth brush to remove the gross plaque.

• Complete debridement of plaque from the fissure is viewed to be essentially impossible and not an imperative for successful etching and sealant retention.

UPDATING TECHNIQUE:

ISOLATION

• Adequate isolation of the tooth is the most critical aspect of the sealant application process.

• Salivary contamination of a tooth surface during or after acid etching will have a deleterious effect on the ultimate bond between the enamel and resin.

• Studies have shown that even a one second exposure of etched enamel to saliva adversely affected bond strength and sealant retention.

• Several studies have shown that rubber dam isolation and cotton roll isolation provide comparable retention rates.

• However, it is obvious that rubber dam provides the best, most controllable, isolation. • When sealants are treatment planned for a tooth in a quadrant where restorative therapy will also be accomplished, the sealant should be placed under rubber dam isolation in the context of the restorative treatment.

UPDATING TECHNIQUE:

ETCHING

• The most commonly used etchant is 37% orthophosphoric acid; it is available as both a liquid and a gel.

• Etchant should be applied to all of the fissures and extend 2mm up the the cuspal inclines.

• Soft tissue exposure to the etchant is to be avoided.

• Historically, etchant times were 30-60 seconds; however, recent studies have concluded that 15-20 seconds is comparable and adequate.

• Rinse time is not important as previously thought (20 seconds). What is critical is that the etchant be completely rinsed away.

• On thorough drying the enamel should present a chalky, frosted appearance; if it does not, it must be re-etched..

DEMINERALIZATION PATTERNS (SEM X 5,000)

Enamel prism centers mainly involved

DEMINERALIZATION PATTERNS (SEM X 5,000)

Enamel prism peripheries mainly involved.

UPDATING TECHNIQUE:

APPLYING THE SEALANT

• All susceptible pits and fissures should be sealed; this includes the molars.

• Recent studies have shown that using priming and bonding agents, as an intermediate step, prior to placing the sealant, increases sealant retention. Therefore it is recommended that a prime and bond technique be used. With some marketed materials this is a two step procedure. However, there are one-step prime and bond products on the market today, and these are recommended as they are more efficient. (3M/ESPE’s Prompt L-Pop and Caulk’s Prime and Bond) • An additional advantage of using prime and bond before placing the sealant, is that should the area become contaminated with saliva, it only needs to be re-washed, not re-etched.

• Care should be taken not to place excess sealant, which may affect the child’s occlusion; and increase the potential for the sealant bond being fractured.

PENETRATION OF MICROSCOPIC SEALANT TAGS

OCCLUSAL SEALANT AFTER REMOVAL OF ENAMEL BY DEMINERALIZATION

INNER SURFACE OF SEALANT AFTER REMOVAL OF ENAMEL BY DEMINERALIZATION

POLYMERIZED SEALANT TAGS (SEM X 3,000)

UPDATING TECHNIQUE:

POLYMERIZATION

• In one study it was found that the longer sealants were polymerized, the more sealant penetrated the microporosities, creating longer resin tags, which are the critical dimension for micromechanical retention.

• Sealants in which polymerization was not effected for 20 seconds after application, had nearly three times longer resin tags than those of sealants polymerized after 5-10 seconds. This is true when bonding composites to etched enamel as well.

• When isolation can be adequately maintained, it appears to be beneficial to wait for 20 seconds after sealant application before applying the light activation.

• The above is applicable only if a prime and bond

UPDATING TECHNIQUE:

EVALUATING THE SEALANT

• All sealants should be visibly and tactually inspected for complete coverage, and the absence of voids or air bubbles.

• Attempts should be made to dislodge the sealant with an explorer.

• An evaluation of the occlusion should be conducted. Filled resin sealants (which we utilize) in contrast to unfilled resin sealants, are not easily abraded and can create occlusal interferences. They should be adjusted with a rotary instrument, if determined to be in hyperocclusion.

• The interproximals of the tooth should be evaluated as well to ensure no sealant has flowed into the area inadvertently.