contamination, which reduces the bond strength. Salivary contamination results in
significantly reduced bond strengths unless removed by thorough washing. Re-etching
of the surface is usually necessary if salivary contamination has occurred.
Bonding agents
Bonding agents used as an additional layer under a resin sealant yield bond strengths
significantly greater than the bond strength obtained when using sealant alone. Initial
results of clinical trials also show increased retention of the sealant when an
intermediate bond is used. New bonding techniques are proving to be less technique
sensitive, with respect to moisture control than erstwhile procedures.
The use of a bonding agent under a sealant on wet contaminated surfaces yields bond
strengths equivalent to the bond strength obtained when sealant is bonded directly to
clean etched enamel without contamination. Most of the data on the subject of using a
bonding agent as part of the sealant procedure supports its use. Use of a bonding agent
would tend to increase the time and cost of the sealant application but in cases where
maintaining a dry surface is difficult or where there are areas of hypomineralization
on the surface, it would have many advantages.
Logically, combination of these technologies to achieve better penetration with less
steps in the application sequence would be beneficial and there is some evidence
already in the use of self-etching primer-adhesive systems. As yet, there has only been
a 2-year follow-up but the early results are promising in relation to retention. Other
studies have shown that there are concerns about micro-leakage compared with
conventional acid etching. The big bonus of the self-etching primer-adhesive system
is the speed with which the operator can apply it. In the application procedure for the
Prompt-L-Pop system, the operator brushes the self-etching adhesive on to the
surface; air thins it, and follows this by immediate placement of the sealant and
polymerization. In the study, the average time operators took for the procedure was
1.8 min compared with 3.1 min for conventional technique. Such time saving is very
useful in young fidgety children. At present, therefore, there are conflicting views on
these systems but with technology moving ever onwards it does seem likely that in the
future it should be possible to achieve good etching and bonding with a simpler
application method.
Most clinicians will employ a resin-based sealant, because they have a good track
record. Many clinical trials have demonstrated the effectiveness of resin sealants and
there are several long-term studies, which show the benefits. Fifteen years after a
single application, resin sealants have shown 28% complete retention of sealants and
35% partial retention on first permanent molars. Where researchers re-applied sealant
to those surfaces that had deficient sealant as determined by yearly exams, 65%
complete retention was obtained and only 13% of the surfaces had caries or
restorations after 20 years.
Retreatment
Sealants placed in the first permanent molars in children of ages 6, 7, and 8 and in
second permanent molars in children of ages 11 and 12 required more re-application
than those placed in older teeth. If the clinician places fissure sealant in newly erupted