Q: What are dental sealants, and how effective are they?

A: Sealants are thin plastic coatings painted onto the back teeth, where two-thirds of all cavities form. The pits and grooves of molars make for great food and plaque traps. Sealants stop bacteria from getting inside the grooves and can be 100 percent effective in preventing cavities.

They are effective, however, only on the sealed surfaces; you still have to brush and floss regularly to prevent cavities between your teeth.

Sealants, which typically last five to 10 years before wearing out, are usually placed on children's new permanent teeth. Only 7.6 percent of school-age children have sealants, and price may be the reason. Sealants can cost between $18 and $45 per tooth and may not be covered by your insurance.