A dental sealant is an acrylic-like material that helps shield out decay-causing bacteria from the chewing surfaces of back teeth. The best time to apply them is when the six-year molars appear. Sealant material forms a protective barrier by bonding to the tooth surfaces and covering natural depressions and grooves in the teeth. More than 75% of dental decay begins in the depressions and grooves of the back teeth. Combined with proper home care and regular dental visits, sealants are extremely effective in preventing tooth decay.