Module 16: Mixed Dentition and Occlusion

mixed dentition: combination of some primary teeth and some permanent teeth

Age 5 years

primary teeth erupt between 2 1/2 to 5 1/2 years old. No permanent teeth visible. Primary incisors, canines, and molars present

Age 7 to 8 years

Age 6 to 7 years

Age 10 to 12

Age 11 to 13

permanent first molars erupt

permanent incisors replace primary incisors

all four mandibular premolars erupt replacing mandibular primary first molars and canines; maxillary permanent first premolars erupt and replace primary first molars

primary canines and primary second molars are lost. All permanent detition

Class I


Canine relation: maxillary permanent canine occludes with the distal half of the mandibular canine and the mesial half of the mandibular permanent premolar

Class II, Division I

Molar relation: buccal groove of mandibular first molar is distal to the mesiobuccal cusp of maxillary first molar by at least the width of a premolar

Molar relation: buccal groove of mandibular first molar is directly in line with the mesiobuccal cusp of maxillary first molar

Canine relation: distal surface of the mandibular canine is distal to the mesial surface of the maxillary canine by at least the width of a premolar

All four maxillary incisors protrude

Class II, Division II

Molar relation: buccal groove of mandibular first molar is distal to the mesiobuccal cusp of maxillary first molar by at least the width of a premolar

Canine relation: distal surface of the mandibular canine is distal to the mesial surface of the maxillary canine by at least the width of a premolar

Both maxillary lateral incisors protrude, central incisors retrude

Class III

Molar relation: buccal groove of mandibular first molar is mesial to the mesiobuccal cusp of maxillary first molar by at least the width of a premolar

Canine relation: distal surface of the mandibular canine is mesial to the mesial surface of the maxillary canine by at least the width of a premolar

Malocclusion

open bite: maxillary anterior teeth do not overlap or contact mandibular anterior teeth

anterior edge to edge bite: incisal surfaces on maxillary and mandibular teeth occlude

Posterior end to end bite: cusps of maxillary teeth occlude with cusps of opposing mandibular teeth

Deep overbite: incisal edges of maxillary anterior teeth are at a level of the cervical third of mandibular anterior teeth

Crossbite: one or more of the mandibular teeth are located facial to their maxillary counterparts

Malpositions

facioversion: tooth that is positioned facial to its normal position

linguoversion: tooth that is positioned lingual to its normal position

supraversion: the extension of a tooth is beyond the plane of occlusion

rotated (torsiversion): a tooth that is turned in relation to its normal position