Symptoms and types of bite class
Normal bite refers to a class in which the molars bite down in alignment. It is also referred to as a balanced bite.
Overbite refers to a molar relationship in which the lower molars bite down posterior to the upper molars. This means they bite down towards the back of the mouth. It is called an overbite because, in this abnormal relationship, the upper jaw and upper front teeth project out over the chin. This creates a convex appearance. In profile, this gives the appearance of receding chin and lower lip.
Underbite refers to a relationship in which the lower molars are anterior (towards the front) of the upper molars. It is called an underbite because, in this atypical relationship, the lower jaw and lower front teeth project further forward than the upper teeth and jaw. This creates a concave appearance. This gives a profile with a prominent chin and lower lip.