There has only been one report of an allergy to the resin used for pit and fissure
sealing and concern has been raised about the oestrogenicity of resin-based
composites. The proposed culprit, bis-phenol A (BPA), is not a direct ingredient of
fissure sealants, but is a chemical that appears in the final product when the raw
materials fail to fully react. The amount released orally is undetectable in the systemic
circulation and concerns about potential oestrogenicity are probably unfounded.
Sealant bulk in relation to application
It is important to remember that the sealant must be kept to a minimum, consistent
with the coverage of the complete fissure system including buccal and lingual pits.
Overfilling can lead to reduction in retention and increased micro-leakage.
Sealant monitoring
Once the sealant has been placed the operator must monitor it at recall appointments
and repair or replenish as necessary. Teeth lose is between 5% and 10% of sealant
volume per year. Partial loss of resin sealant allows ingress of bacteria into the fissure
system. This leaves that surface equally at risk from caries compared to an unsealed
surface.
Cost-effectiveness
Cost-effectiveness will depend on the caries rate for the children in the population.
Where there is a higher caries rate, generalized sealing will protect more surfaces that
would have become carious in the future. However, if the caries rate is very high, then
the risk of developing interproximal lesions is also higher and may lead to a two
surface restoration even when the fissure sealed surfaces remain caries free. In low
caries areas, the cost-effectiveness of sealant application en masse is questionable and
the dentist should assess each child's individual risk factors. In contrast to this general
concept, one study has shown that it is 1.6 times as costly to restore the carious
lesions in the first permanent molars in an unsealed group of 5-10-year-old children
living in a fluoridated area than it is to prevent them with a single application of pit
and fissure sealant. This study also revealed a greater number of lesions if sealant was
not utilized.
Sealing over caries
Once caries has been diagnosed it is important to determine its extent. If there is clear
unequivocal evidence that the lesion does not extend beyond the enamel, then the
surface may be sealed and monitored both clinically and radiologically. If the lesion
extends into the dentine, the dentist would normally place either a preventive resin
restoration (PRR), or if in an area of occlusal load, a conventional restoration.
However, several authors have shown that dentinal carious lesions do not progress
under intact sealants. Nevertheless, if the sealant were to fail immediately or shortly
after application, then the lesion would have 4-6 months to progress before the next
review. We do not advocate sealing over caries except in very exceptional
circumstances, that is, very nervous children who cannot cope with even minimal
intervention dentistry.