Teeth have grooves on their occlusal surfaces (biting surfaces), and on the side surfaces. These grooves are called fissures.
All back teeth (Molars and Premolars) have fissures, and sometimes front teeth have them on the inner surface that we cannot see directly.
Tooth decay starts by a layer of bacteria attaching itself to the tooth surface, forming what is called Dental Plaque. The plaque starts producing acid that will wear down tooth structure. When we brush our teeth, we aim to remove the Dental Plaque to prevent wearing down by the acid. However sometimes the fissures on our teeth are either too deep or too narrow to be cleaned by the tooth brush, even the bristles of the tooth brush cannot go into these fissures. Thus we end up with Dental Plaque within the fissures, even if we are meticulous with brushing, and we end up with dental decay no matter what.

As a prevention measure against fissure plaque causing decay, we aim at covering these fissures with a resin material to prevent the formation of the plaque. This keeps the tooth healthy. The procedure doesn’t involve any drilling, or very minimal drilling that doesn’t need any numbing. A conditioner is then applied to the tooth surface, to be followed by the resin material.