Which of the following is not a root canal sealer used to seal unfilled voids?

Fluoride varnish is not a root canal sealer because its primary purpose is to provide a protective coating and deliver fluoride for the prevention of dental caries, rather than to seal unfilled voids in root canals. Fluoride varnish is typically used on the surfaces of teeth and is beneficial in protecting against decay, especially in vulnerable areas, but it is not formulated to penetrate or seal the intricate areas within the root canal system.

In contrast, Resilon, pulp canal sealer, and glass ionomer are all materials specifically designed for root canal procedures. Resilon is a thermoplastic root canal filling material that is used in conjunction with a sealer to fill the canal space. Pulp canal sealer is a specific type of sealer formulated to aid in filling voids and ensuring that bacteria and fluids cannot enter the canal. Glass ionomer is also used in endodontics due to its adhesive properties and ability to seal effectively. Each of these materials serves the function of sealing the complex anatomy of a root canal, which is essential for successful endodontic treatment.