An operculum is the name of a piece of gum tissue that lies overtop the biting surface of a tooth. Generally speaking, an operculum occurs when teeth are erupting and, most of the time, will resolve on their own when the tooth erupts fully. The most common teeth to develop operculums are the 1st, 2nd and 3rd molars as they erupt. The trickiest to deal with is an operculum occurring on a 3rd molar since they are difficult to reach. Operculums form when the molars are breaking through the gum tissue, and the gum tissue doesn’t completely pull away from the biting surface of the tooth. They occur on the last molars in the mouth due to the curvature of the gums at the back of the mouth. It is essential to keep the area as clean as possible if you notice an operculum forming and to see your dentist.