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The first sealant clinical trials used cyanoacrylate-based materials. These were replaced by dimethacrylate-based products which were marketed. A major difference between marketed sealants is their method of polymerization. First-generation sealants were initiated by ultraviolet light, second-generation sealants are autopolymerized, and third-generation sealants use visible light. Over time, clinical retention was found to be greater for second generation as compared with first-generation sealants. Five to 7 years after initial application the pits and fissures of approximately one third of teeth treated with first-generation sealants were fully protected as compared with two thirds of the teeth treated with second-generation sealants. First-generation, ultraviolet light initiated, sealants are no longer marketed. Clinical reports indicate that retention is similar for second- and third-generation systems, but longer clinical evaluations are necessary. A recent innovation is the addition of fluoride to sealants. Fluoride release to the saliva from a fluoride sealant system is rapid, but clinical studies are needed to determine if the fluoride addition improves caries inhibition.

Within the last 20 years there has been a decrease in the caries prevalence of US schoolchildren, a change in the intraoral caries pattern, and a slowing of the progress of lesions. Simultaneously, the prevalence of enamel milder, cosmetically acceptable forms and is more noticeable in fluoride-deficient communities than those with optimal or above-optimal water fluoride concentrations. Circumstantial evidence indicates that a principal contributor to the caries decline is the extensive use of fluoride dentifrices. Conversely, although use of a fluoride dentifrice can add to the total daily amount of ingested fluoride in preschool children, there is little evidence to suggest that dentifrice ingestion is a principal factor causing the fluorosis increase. The value of fluoride methods may be assessed in relative or absolute terms. The relative, or percentage, caries reduction attributed to fluoride mouthrinses and gels appears to be a property intrinsic to the methods themselves and generally is little affected by the caries activity of the population being treated. Conversely, the absolute, or numerical, caries reduction is dependent upon the level of disease in the population. Thus, the reported caries decline reduces the number of surfaces prevented from developing caries, even though the percentage reduction remains substantially unchanged. Although inadvertent ingestion of fluoride can result from the use of mouthrinses and gels, there is little evidence to suggest that they have contributed to the fluorosis increase. When using topical methods, prudence should prevail to avoid ingestion of fluoride. Fluoride dentifrices should continue to be used routinely, and although lower potency dentifrices may be considered, the literature does not provide strong support for their need. Use of fluoride mouthrinses and gels for individual patients should be predicted upon their caries activity or risk. Use of these methods in public health programs is a matter of cost-effectiveness, which will be influenced by the caries prevalence of the target population.

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