The maxillary(upper jaw) and mandibular (lower jaw) teeth, when closed correctly, are referred to as being occluded or having a normal occlusion.
Orthodontists are concerned with teeth that do not occlude properly because of the size of the patient’s jaws, or because of crowding or displacement of teeth.
Malocclusion refers to abnormal or malpositioned relationship of the maxillary teeth to the mandibular teeth when occluded.
According to Angle’s classification, any deviation from normal occlusion is regarded as malocclusion.
Class I Malocclusion
Class I malocclusion consists of a normal relationship with the molars, but the anterior teeth will be out of alignment with crowding, malpositioned teeth, cross bites, etc.
Class II Malocclusion
In class II malocclusion, also known as distoclusion, the mandible is in an abnormal distal relationship to the maxilla.
Class II Malocclusion has two divisions to describe the position of the anterior teeth.
Class II Division 1 is when the maxillary anterior teeth are proclined and a large overjet is present.
Class II Division 2 is where the maxillary anterior teeth are retroclined and a deep overbite exist.
Class III Malocclusion
In class III malocclusion, also known as mesioclusion, the body of the mandible (lower jaw) is in an abnormal mesial relationship to the maxilla(upper jaw).
There is an appearance of the mandibular anterior teeth protruding in front of the maxillary anterior teeth, also referred to as an underbite.