CHAPTER 17 Pit and Fissure Sealants and Preventive Resin Restorations
In 1955, Buonocore described the technique of acid etching as a simple method of increasing the adhesion of self-curing methyl methacrylate resin materials to dental enamel.1 He used 85% phosphoric acid to etch enamel for 30 seconds. This produces a roughened surface at a microscopic level, which allows mechanical bonding of low-viscosity resin materials.
The first materials used experimentally as sealants were based on cyanoacrylates but were not marketed. By 1965, Bowen had developed the bis-GMA resin, which is the chemical reaction product of bisphenol A and glycidyl methacrylate.2 This is the base resin to most of the current commercial sealants. Urethane dimethacrylate and other dimethacrylates are alternative resins used in sealant materials.
CLINICAL TRIALS
In 1983, a National Institutes of Health Consensus Panel considered the available information on pit and fissure sealants and concluded that “the placement of sealants is a highly effective means of preventing pit and fissure caries.… Expanding the use of sealants would substantially reduce the occurrence of dental caries in the population beyond that already achieved by fluorides and other preventive resources.”3
In 1991, Simonsen reported on a random sample of participants in a sealant study recalled after 15 years.4 He reported that, in the group with sealant, 69% of the surfaces were sound 15 years after a single sealant application, whereas 31% were carious or restored. In the group without sealant, matched by age, gender, and residence, 17% of the surfaces were sound, whereas 83% were carious or restored. He also estimated that a pit and fissure surface on a permanent first molar is 7.5 times more likely to be carious or restored after 15 years if it is not sealed with a single application of pit and fissure sealant.
A 1996 survey of Indiana dentists5 found that 91% of them were placing sealants on permanent teeth, whereas in 1985 a similar study6 had found that only 73.5% were placing sealants on permanent teeth. This increased use of sealants may be related to increased practitioner comfort with the materials, because a direct correlation was found between sealant use and year of graduation from dental school. The increase may also be related to a decreased concern over the possibility of caries developing under the sealant.
Several studies have reported decreased viable bacterial counts in occlusal fissures that have been sealed. Handleman and colleagues placed an ultraviolet-radiation–polymerized sealant on pits and fissures of teeth with incipient caries.7 They reported a 2000-fold decrease in the number of cultivable microorganisms in the carious dentin samples of the sealed teeth compared with unsealed control teeth at the end of 2 years.
Going and colleagues obtained bacteriologic samples from teeth that had been sealed with an ultravioletradiation–polymerized sealant for 5 years.8 They found an apparent 89% reversal from a caries-active to a caries-free state in the sealed teeth.
Jeronimus and associates placed three different pit and fissure sealants on molars with incipient, moderate, and deep carious lesions.9 Samples of carious dentin were removed immediately after and 2, 3, and 4 weeks after placement of the sealants and bacteriologic cultures were made. They reported usually positive culture results in teeth where the sealant was lost. Although their short-term study indicated that incipient carious lesions may not be of prime concern when sealants are applied, they cautioned against the use of sealants over deeper lesions because of the potential for advancement of caries when sealants over these lesions are lost. One must keep in mind that their deep-lesion group consisted of teeth with caries that had advanced pulpally greater than half the distance from the dentinoenamel junction.
Going declared that, given the results of many well-documented studies, practitioners’ fear of sealing pits and fissures with incipient caries is not warranted.10 He pointed out that sufficient studies of scientific merit reported negative or low bacterial concentrations after sealant had been in place for several years.
Wendt and Koch annually followed 758 sealed occlusal surfaces in first permanent molars for 1 to 10 years.11 At the end of their study, evaluation of the surfaces that had been sealed 10 years previously revealed that only 6% showed caries or restorations. Romcke and associates annually monitored 8340 sealants placed on high-risk (for caries) first permanent molars during a 10-year period.12 Maintenance resealing was performed as indicated during the annual evaluations. One year after the sealants were placed, 6% required resealing; thereafter 2% to 4% required resealing annually. After 8 to 10 years, 85% of the sealed surfaces remained caries free.
Retrospective studies based on billing data from large third-party databases reveal that sealant use is still surprisingly low, even in populations for which sealants are a covered benefit.13,14 In addition, these studies show that the effectiveness of sealants in preventing the need for future restorative care on the sealed surfaces declines after the first 3 years following sealant treatment. These data argue again for the importance of vigilant recall and upkeep of sealants after placement.
Another concern is the placement of sealants immediately after topical fluoride application. Clinical and in vitro studies have shown that topical fluoride does not interfere with the bonding between sealant and enamel.15,16
RATIONALE FOR USE OF SEALANTS
The 2008, Evidence Based Clinical Recommendations for the Use of Pit and Fissure Sealants report by the American Dental Association on Scientific Affairs concluded that sealants are effective in caries prevention and can prevent the progression of early noncavitated carious lesions.17
The American Academy of Pediatric Dentistry’s Pediatric Restorative Dentistry Consensus Conference18 confirmed support for sealant use and published these recommendations: