Ch. 1: Occlusion and Lobes

Why is malocclussion unfavorable?

poor appearance, interfere with normal growth and development, interfere with occlusion, improper muscle function, and mouth breathing

class I molar relationship

mesiobuccal cusp of maxillary 1st molar occludes with the buccal groove of mandibular 1st molar

class I canine relationship

maxillary canine occludes with distal half of mandibular canine and mesial half of mandibular 1st premolar

class I malocclusion

normal molar and canine relationship but may have abnormal orientation of incisors or malposition of some teeth

class II distocclusion

mandibular teeth are posterior to the normal position in their relationship to maxillary teeth

class II molar relationship

buccal groove of mandibular 1st molar is distal to the mesiobuccal cusp of maxillary 1st molar

class II canine relationship

distal surface of the mandibular canine is distal to the mesial surface of the maxillary canine

If alignment differs by less than the distance of a premolar in class II disto-occlusion then it is known as a _______.

tendency toward class II

class II division I

maxillary arch is narrowed and lengthened causing protruded maxillary incisors

class II division II

crowded anterior teeth with one or more of the maxillary incisors retruded

class III malocclusion

mandibular teeth are anterior to normal position in relationship to maxillary teeth

class III molar relationship

buccal groove of the mandibular 1st molar is mesial to the buccal cusp of the maxillary 1st molar

class III canine relationship

the distal surface of the mandibular canine is mesial to the mesial surface of the maxillary canine

upper teeth sit behind the lower teeth

anterior crossbite

upper back teeth bite inside the lower back teeth

posterior crossbite

edges of upper and lower teeth directly meet

edge to edge

cusps of upper and lower teeth come in direct contact

end to end

upper and lower front teeth do not overlap causing a gap

open bite

horizontal distance between the upper and lower front teeth

overjet

malocclusion where the lower front teeth protrude past the upper front teeth

underjet

amount the upper teeth overlap the lower teeth pertaining to vertical dimension

overbite

positioned labial to normal

labioversion

positioned buccal to normal

buccoversion

positioned lingual to normal

linguoversion

elongated above the line of occlusion

supreversion

depressed below the line of occlusion

infraversion

turned or rotated

torsiversion

primary division of tooth crowns usually separated by primary grooves

lobes

How many lobes do anterior teeth have?

3 labial (mesio, middle, disto) + 1 lingual = 4 lobes

What are the anterior teeth lobes divided by?

mesiolabial and disto labial depressions on the facial

How many lobes do most premolars have?

3 buccal (mesio, middle, disto) + 1 lingual = 4 lobes

What premolar instead has 5 lobes (2 lingual lobes instead of just 1)?

mandibular 2nd premolar

What is the general rule for molars

number of cusps = number of lobes

How many lobes do maxillary molars have?

4 lobes (mesiobuccal, distobuccal, mesiolingual, and distolingual)

How many lobes do most mandibular molars have?

4 lobes (mesiobuccal, distobuccal, mesiolingual, and distolingual)

How many lobes does the 1st mandibular molar have?

5 lobes (extra lobe=distal lobe)