Dental sealants fill in and cover the rough and deep groove system that is located on top of the chewing surfaces of your molars and premolars. These grooves are development and vary in depth and irregularity between patients. This is where the cookies get stuck and linger even after rigorously brushing. These are also the nooks and crannies where bacteria likes to hide. Because the grooves are microscopic at their depth, this is the first place that cavities start in kids who haven't had sealants. Cavities can be progress without notice for years.
Our first indication that there is bacteria in the grooves is stain. Stain usually means bacteria. Bacteria in the right environment will produce acid that causes cavities. Eighty percent of decay on young permanent teeth occurs in these pits and groove areas. To achieve the best preventative benefit, sealants should be placed as soon as is possible once the tooth erupts into the oral environment. The deep grooves need to be cleaned thoroughly before sealant placement so as not to leave plaque and bacteria behind. If not cleaned thoroughly, the sealant can easily come off or decay can start beneath the sealant, making the decay difficult to diagnose. Sealants are a very useful, and in my professional opinion, necessary prevention tool.
Dental sealants are not permanent but when placed correctly should last at least 5 years.
Patients who are grinders or ice/hard candy chewers or have poor oral hygiene tend to lose or chip sealants which is why we check them at every 6 month recare appointment for possible repair or replacement to make sure the sealant is intact and the groove protected.
My adult children have had sealants placed on all of their permanent teeth and they are still intact after more than 12 years.