The most common kinds of oral cysts are periapical cysts, caused by infections in the pulp of the tooth, and dentigerous cysts, usually formed by impacted wisdom teeth. There is other type of cysts and some tumours that grows in the jawbone. These are usually painless unless infected, and are not noticed until they become large enough to cause a bulge in the jawbone. While cysts and most of the tumours are benign, their removal is necessary to prevent their spreading and damaging nearby bones or teeth and other complications