A student asked me yesterday if I recommended using an adhesive beneath a fissure sealant. I was aware that the use of adhesives has been researched but was not up to date.
A quick search in TRIP led me to some American Dental Association guidelines that included some discussion of this:
Recommendations on using separate etch and then one-step prime & bond were equivocal. However, they discouraged use of all-in-one etch-prime-bond as these may result in worse retention of the sealant.
These guidelines are a bit dated as the last search was up to 2006, even though the guidelines were published in 2008.
A search in pubmed using a basic strategy brought up several more recent RCTs that seem (from the abstract only) to agree with these recommendations.