How is a dental filling and a dental sealant different?

Sealants-fillings: Sealants are resins, less viscous than fillings, do not require tooth structure removal and are meant to protect defective pits and fissures only on teeth. Fillings replace tooth structure destroyed by cavities and fractured teeth.

Filling v sealant: Dental fillings are restorative procedures that repair teeth affected by decay, fracture, excessive wear facets, they replace damaged or missing tooth structure. Dental sealants are preventitive procedures whereby areas of the tooth structure that are more susceptible to future decay are sealed off with a resin to restrict plaque, bacteria and food debris from lodging in the grooves and fissures.

Depth, type: Typically a sealant preparation does not penetrate the enamel. The sealant is usually a flowable resin, suited to flow in the nooks/crannies of the tooth, but not intended for heavy chewing and wear, or to strengthen/bond tooth surfaces together. A filling typically penetrates the enamel removing decay, often bonds portions of the tooth together, restores missing tooth and uses stronger resin.

Sealant vs Filling: Dental sealants are used to prevent and protect the chewing surfaces of back teeth from dental caries. Fillings are placed as a treatment to restore teeth to their normal shape, appearance and function after decay has penetrated the tooth.