The wisdom teeth (Third Molar) usually start to erupt into the oral cavity during late adolescence.
During the eruption of the wisdom tooth in some cases, they might not have the space or come in partial abnormal positions making it below the occlusal level, which leads sometimes to inflammation of the tissues surrounding the tooth because either holding food particles and debris and is a hotbed for bacteria causing infection or keep biting that gum in between your teeth during having food or talking.
This case is called pericoronitis which can be either short-term (acute) or long-term (chronic) & usually develops in people between 20 - 40 years old.
The symptoms of pericoronitis can be different between patients depending on the severity of the infection or the tooth position inside the oral cavity.
These symptoms might be either acute or chronic & include:
Swollen gum in the affected area