What is the difference between a dental filling and sealant?

Dental sealants: Dental sealants are thin plastic coatings that are applied to the grooves on the chewing surfaces of the back teeth to protect them from tooth decay. Most tooth decay in children and teens occurs on these surfaces. Sealants protect the chewing surfaces from tooth decay by keeping germs and food particles out of these grooves.

Pre vs. post cavity: Sealants are place to prevent cavity from developing in grooves of molar teeth. This is done before the cavity. This does not mean once you get sealants, you will be cavity free. Sealants will decrease the chance you will get dental cavity. A dental filling is placed after the cavity has developed. $40 preventative sealants vs. $200 dental filling. Which would you choose?

Dental filling: A sealant involves filling in the grooves, pits, and fissures of the teeth with a thin filling material/sealant material that prevents food from getting trapped in them and aids in cleaning. Fillings are done when dental decay is present. The decay is removed (typically the tooth has to be numbed prior to doing this). Once the decay is out the filling is placed to replace hole where the decay was.