Occlusion refers to the alignment of teeth and the way that the upper and lower teeth fit together (bite). So, malocclusion means the teeth are not aligned properly that is either the upper teeth overlap the lower teeth or vice-versa.

Malocclusion can either be inherited from parents or acquired through bad habits.Childhood habits such as thumb sucking, tongue thrusting and prolonged use of a bottle, extra teeth, lost teeth, impacted teeth, or abnormally shaped teeth, ill-fitting dental fillings, crowns, or braces, misalignment of jaw fractures after a severe injury, tumors of the mouth and jaw.

Many types of malocclusion are not preventable. Control of habits such as thumb sucking may be necessary in some cases. However, early detection and treatment may optimize the time and method of treatment needed.