What substance must not be administered prior to placing sealants?

Fluoride must be avoided prior to placing pit and fissure sealants because it can interfere with the bond between the sealant material and the tooth structure. The effectiveness of sealants largely depends on their proper adhesion to the enamel surface, and fluoride application can create a barrier that may prevent optimal bonding.

In contrast, antibiotics, analgesics, and desensitizers do not affect the bonding process of sealants in the same way that fluoride does. Antibiotics are used to treat infections, analgesics are pain relievers, and desensitizers can help manage sensitivity in certain procedures, but they do not impact the adhesive qualities necessary for sealants. Therefore, it is essential to ensure the enamel surface is clean and free from any products that could weaken the sealant's effectiveness, making the exclusion of fluoride crucial prior to application.