Angle's classification of occlusion

1: eponym for a classification system of occlusion based on the interdigitation of the first molar teeth originally described by Angle as four major groups depending on the anteroposterior jaw relationship. Class IV is no longer in use. Class I (normal occlusion or neutrooclusion): the dental relationship in which there is normal anteroposterior relationship of the jaws, as indicated by correct interdigitation of maxillary and mandibular molars, but with crowding and rotation of teeth elsewhere, i.e., a dental dysplasia or arch length deficiency. Class II (distoclusion): the dental relationship in which the mandibular dental arch is posterior to the maxillary dental arch in one or both lateral segments; the mandibular first molar is distal to the maxillary first molar. Class II can be further subdivided into two divisions. Division 1: bilateral distal retrusion with a narrow maxillary arch and protruding maxillary incisors. Subdivisions include right or left (unilaterally distal with other characteristics being the same). Division 2: bilateral distal with a normal or square-shaped maxillary arch, retruded maxillary central incisors, labially malposed maxillary lateral incisors, and an excessive vertical overlap. Subdivisions include right or left (unilaterally distal with other characteristics the same). Class III (mesioocclusion): the dental relationship in which the mandibular arch is anterior to the maxillary arch in one or both lateral segments; the mandibular first molar is mesial to the maxillary first molar. The mandibular incisors are usually in anterior cross bite. Subdivisions include right or left (unilaterally mesial with other characteristics the same). Class IV: the dental relationship in which the occlusal relations of the dental arches present the peculiar condition of being in distal occlusion in one lateral half and in mesial occlusion in the other (no longer used).