Seal Away Caries Risk

Since the first meta-analysis of clinical trials was conducted on the efficacy of sealants in 1993,¹ a significant body of evidence has demonstrated their ability to prevent pit and fissure caries in children,^1–20 making them one of the most successful preventive measures in dentistry.³ In the 1950s, Buonocore introduced the acid-etch procedure, which laid the groundwork for the development of sealants as the best preventive agent against pit and fissure caries.^2,12

Placing a dental sealant on the chewing surfaces of a tooth with deep pits and fissures protects it against food particles and bacterial plaque. The sealant works by creating a physical barrier separating the tooth surface from the acids produced by plaque, which cause tooth decay.¹² The acid-etch technique also is part of the move toward a minimally invasive approach to restorative dentistry, which is based on preserving healthy tooth structure through prevention, remineralization, and minimal intervention.²¹

Placement of dental sealants is recommended depending on patients’ level of caries risk.¹³ The American Dental Association (ADA) Council on Scientific Affairs recommends the placement of dental sealants on the primary and permanent teeth of children, adolescents, and adults who are at increased risk of caries.⁷ The best predictors of caries risk are prior caries experience, history of fluoride use, fissure anatomy, plaque load,¹⁵ and dietary habits. Sealants are most often placed on newly erupted molars, which contain many pits and fissures.^2,12 They also can aid in caries prevention when applied to premolars.²²

Research shows that a sealant must seal over the tooth’s occlusal surface—completely keeping out fermentable food substrates—in order to be effective.⁶ Sealants can last up to 10 years, but oral health professionals need to periodically check their status and replace them when necessary.²³

SEALANT MATERIALS

There are a number of pit and fissure sealants including resin-based cements and glass ionomer cements. Resin-based sealants are further classified according to their mechanism for polymerization or content. The first generation of sealants was activated by ultraviolet light. Today, some sealants are autopolymerized, while others release fluoride.⁴ A sealant adhesive is also available that eliminates the need for acid-etch liquid or gel. This adhesive is dried after application instead of being rinsed off.²⁴

By the late 1960s, a viscous resin was found to be resistant to degradation and produced a tenacious bond with the etched enamel. This resin was formed by reacting bisphenol A (BPA) with glycidyl methacrylate (GMA). This class of dimethacrylate resins is known as Bis-GMA.^6,12 The presence of BPA in sealant materials is controversial due to BPA’s role as a known endocrine disruptor. Current evidence shows, however, that there is no risk of toxic exposure to BPA after sealant placement, and the ADA published a position paper stating there is no basis for health concerns relative to BPA exposure from any dental material.²⁵

Some commercially-available resin sealants are free of inert fillers, while others are semi-filled. Sealant materials can be clear, tinted, or opaque. Fluoride-containing resin-based sealants were introduced in 1974.⁶ Traditionally, dental resins are based on Bis-GMA and urethane dimethacrylate monomers that are hydrophobic, repel water, and require a dry environment.^10,18 There are options, however, that do not contain Bis-GMA. The precision of the technique and the maintenance of a dry field are crucial to retaining traditional sealants. Factors that can interfere with sealant retention include technique errors, most commonly moisture contamination; inadequate acid etching, which results in a lack of adhesion; incorporation of air bubbles into the sealant material; and incomplete removal of debris from pits and fissures prior to acid etching.^10,14

SEALANTS THAT CAN BE PLACED IN A MOIST FIELD

Resin-based materials also are now available that enable sealants to be placed in a slightly moist field—simplifying the application process. This quality can be especially helpful when treating children, as it can be challenging to maintain a dry field in this patient population. After acid etching and rinsing, the slightly moist tooth surface appears glossy compared to traditional hydrophobic sealant materials, which leave the tooth surfaces with a chalky white appearance.

GLASS IONOMER MATERIALS

Glass ionomer sealant materials are hydrophilic and fluoride releasing. They bond chemically to the tooth and recharge their fluoride release from exposure to topical fluorides.⁹ Due to their hydrophilic nature, glass ionomer sealants are less technique sensitive. In clinical trials, however, glass ionomer sealants exhibited shorter retention than resin sealants.^{2–4,6,7,9,10,13–15,17} As such, glass ionomer materials are typically reserved for use as interim sealants when cooperation levels or tooth eruption status makes achieving adequate isolation difficult.⁴

SURFACE-PREREACTED GLASS IONOMER

A new dental sealant material that is part of a fluoride-recharging pit and fissure sealant is now available. This product is a resin sealant material that contains surface-prereacted glass (S-PRG) ionomer. This sealant uses a self-etching primer, eliminating the need for phosphoric acid etchant.²² A study evaluated the fluoride released from this sealant initially and after recharging. Results showed that significant fluoride recharging was provided with the S-PRG sealant. These findings suggest that sealants with S-PRG filler may support the remineralization process and inhibit demineralization.²⁶

CONCLUSION

Dental sealants are part of a preventive program that includes the use of fluoride, dietary counseling, plaque control, and regular dental visits to evaluate sealed teeth for sealant integrity and retention with the intention of eliminating or halting caries progression.^11,17,20 Evidence-based studies support the use of dental sealants in pit and fissures to prevent caries.^{2,3,5–20,25} Effective sealant placement is affected by clinical judgment, caries risk, time of placement, patient cooperation, operator expertise, method of isolation, and consistent recare.¹⁹

REFERENCES

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From Dimensions of Dental Hygiene. June 2015;13(6):34,36.