Types of Pit and Fissure Sealants
Curing of sealant materials occurs one of two ways. Some sealants are chemically cured through a process called autopolymerization. These materials are dispensed as two components. As soon as the components are mixed the polymerization begins. The curing is complete in approximately 60 seconds. Other sealant material is cured with visible light. When using the light cured materials, it is very important the curing light is of high quality and is tested frequently for the value of the light emitted. Resin-based sealants are not fluoride releasing and their application is more technique sensitive (moisture concerns). In the mid-1990s safety concerns were expressed regarding leaching of bisphenol-A (BPA) from the sealants and a possible oestrogenic effect. However, studies have concluded that the short term risk of oestrogenic effects from treatments using BPA resins is insignificant and that BPA released orally may not be absorbed at all or may only be present in nondetectable amounts in the systemic circulation.6,7
Glass ionomer based sealants are less vulnerable to moisture and have fluoride releasing properties. The fluoride is released from the sealant after polymerization. Previously, compared to resin-based sealants, a lower retention of glass ionomer sealants had been reported but the caries prevention effect is significantly higher with the glass ionomer, as it releases fluoride. With the development of resin modified photopolymerizable ionomers, this disadvantage has been minimized.3 Resin-modified glass ionomers (RMGI) undergo more wear than pure resin sealants. However, there is evidence of residual RMGI retention in the deepest portions of the pit and fissure, with sustained fluoride release. Recent studies show little difference in overall caries prevention, however, more conclusive research is needed.3,8
Dental material manufacturers offer a variety of sealant materials designed to meet the preferences of individual operators. These products include sealant materials that are unfilled, filled with an opaque, clear, and colored and those products that change color when cured. Convenient unit-dosed material is also available. There appears to be no difference in the retention rate. The filled materials are often easier to see and monitor, but the clear materials allow the operator to continue to see the filled fissures. Sometimes operators prefer the colored sealants to make monitoring retention easier. Patients and parents should be consulted prior to the placement of colored sealants. The dental personnel should be aware of the filler content in the sealant being utilized. The higher the percentage of filler, the more important it is to check and adjust the occlusion when the sealant is high in occlusion.9 It is very important that the curing light penetrates the sealant being placed to ensure maximum polymerization.