The adjective dental describes things that have something to do with teeth. Dental floss is the waxed string you use to clean between your teeth.
A dental hygienist is the dentist's assistant, the one who cleans and polishes your teeth. When your dentist's office calls to remind you about your appointment, they might say, "You have a dental cleaning scheduled for next week." In phonetics, a dental is a sound that's made with your tongue touching your top teeth, like th-. In Middle French, dental means "of teeth," from the Latin dens, "tooth."