Dental sealants are manufactured to be medical-grade, meaning they are safe. They are made from resins, which is the basic component of plastic but can also be plant-based. They can also be made from glass ionomers, which is a glass powder mixed with a water-soluble acid.
A sealant can’t be put onto your teeth as part of an exam or without you knowing. They are usually painted on with a brush on your back teeth where you chew the most. After being applied, the dentist has to harden the sealant. An ultraviolet light is used for this.