The grooves on teeth are often smaller than a single tooth brush bristle. Because the grooves are so small they can't be effectively kept clean and are a common place for people to develop cavities. A dental sealant is a resin (a special type of plastic) that is applied over these grooves. The dental sealant prevents food and bacteria from entering these grooves. Preventing food and bacteria from entering these grooves prevents cavities from forming. A dental sealant done well has historically been an excellent way to decrease the risk of having cavities. It does not do anything to decrease the risk of cavities from forgetting to floss.
Sealants are so effective in preventing cavities that many times they are offered at schools to children unable to see a dentist. Oftentimes these sealants are placed by dental students, or dental hygiene students, or others with less training than a dentist. There has been some concern that sealants placed by inexperienced individuals in a less than ideal setting (at school) may not lower the child's risk for cavities and may even increase their risk.
In November of 2009, the Journal of the American Dental Association published the findings of Barbara F. Gooch, DMD and others in their article "Preventing Dental Caries Through School-Based Sealant Programs."
Beginning in 2005 they looked at the dental sealants ability to help prevent cavities. In looking at 10 different studies, they found that on average cavities were reduced by 59% after more than 4 years. That's great news and supports what we had assumed. You will decrease the odds of getting a cavity in a tooth by 60% if the tooth is sealed.
But what if the sealant is not placed well? Does that increase the risk of getting a cavity? They found in looking at seven studies that teeth where a sealant was placed but then lost or partially lost were at same risk to get cavities as if a sealant were never placed. So having a sealant, even a bad one, does not increase your rate to get cavities.
So what's the takeaway message. Children's teeth should be sealed to decrease their risk for cavities and this can be done successfully in a school-based program.
Most insurance companies cover sealants on back teeth up to a certain age. There is less evidence to support the use of dental sealants in adults. However, those adults that are at high risk for cavities should probably have their molars sealed as well.