Aetiology (causes of malocclusion)

Question 1

1. Skeletal

Answer 1

size and position of bony arches, this is a genetic feature

Question 2

2. Soft tissues

Answer 2

as the teeth erupt, they are influenced by the lips, cheeks + tongue which apply pressure to impact upon the tooth position. most often they guide the teeth into correct position by sometimes impedes or causes abnormal movements/positions

Question 3

3. Local factors

Answer 3

the shape + position of opposing + adjacent teeth help guide teeth into correct place, if teeth are lost early or there are additional teeth, this will interfere with placement

Question 4

Malocclusion

Answer 4

the abnormal or malpositioned relationship of maxillary or mandibular teeth. It is rarely a result of pathology + can be due to habits such as thumb sucking, occasionally genetic e.g some syndromes

Question 5

Developmental causes

Answer 5

disturbances in embryonic development i.e cleft lip + palate

Question 6

Congenitally missing teeth

Answer 6

Anodontia - absence of all teeth (rare)
Oligodontia - absence of many but not all teeth (rare)
Hypodontia - absence of a few teeth (fairly common)

Question 7

Primary teeth

Answer 7

give rise to permanent teeth so if missing, the permanent tooth will also be missing, however, the presence of a primary tooth will not always mean the permanent tooth will be present

Question 8

Missing permanent tooth

Answer 8

usually in the last series i.e second incisor, second premolar etc

Question 9

Malformed + supernumerary teeth

Answer 9

an abnormality in the size or shape of a tooth occurs in early development stage. the most common is variation in size, seen especially in maxillary lateral incisors unless the teeth are matched for size it is impossible for normal occlusion

Question 10

Ectopic eruption

Answer 10

a tooth bud is improperly placed so the tooth erupts in the wrong place often upper canines as the path of eruption is long and the tooth become deflected

Question 11

Improper guidance

Answer 11

permanent teeth may have insufficient space into which to erupt following the early loss of primary teeth and become deflected out of line of occlusion

Question 12

Interference with eruption

Answer 12

teeth may be prevented from erupting into their correct occlusal positions by several factors: dense sclerotic bone, supernumerary teeth, fibrous gingivae, primary roots

Question 13

In addition

Answer 13

malocclusion may develop if delayed eruption allows teeth to drift out of their correct position (some babies are born with teeth which may also cause problems later in development)