Aetiology of Malocclusion

Question 1

What is the definition of a local cause of malocclusion?

Answer 1

A localised problem or abnormality within either arch, usually confined to one, two or several teeth proceeding a malocclusion.

Question 2

What is a supernumerary tooth/teeth?

Answer 2

A tooth or tooth like entity which is assertional to the normal series.

Question 3

What are the four types of supernumerary?

Answer 3

Conical
Tuberculate
Supplemental
Odontome

Question 4

What is a conical supernumerary?

Answer 4

Conical shaped extra tooth
Usually doesn’t impact eruption of the permanent tooth but can displace the adjacent tooth.
Usually close to the midline.

Question 5

What is a tuberculate supernumerary tooth?

Answer 5

Tend not to erupt, barrel-shaped tooth.
Usually come in pairs.
Can cause permanent teeth to not erupt.

Question 6

What is a supplemental supernumerary tooth?

Answer 6

Extra tooth of normal morphology.
Commonly upper laters or lower incisors.
Can be third molars, fourth molars.

Question 7

What is hypodontia?

Answer 7

Developmental absence of one or more teeth.
Strong genetic component.

Question 8

What are the most common teeth to be missing in a child?

Answer 8

Upper laterals and second premolars.

Question 9

In terms of retention of primary teeth, what would set alarms bells off?

Answer 9

A difference of more than 6 months between shedding of contralateral teeth.

Investigate with radiograph (OPT).

Question 10

Why might a primary tooth be retained in the mouth?

Answer 10

Lack of permanent successor
Ectopic successor
Infra-occluded primary molars
Dentally delayed in terms of development
Pathology/supernumerary

Question 11

What are the treatment options for a patient with a retained primary tooth and no permanent successor?

Answer 11

Maintain primary tooth if good prognosis
Extract deciduous tooth early and encourage spontaneous space closure.

Question 12

What does it mean if a tooth is infra-occluded?

Answer 12

Process where a tooth fails to achieve pt maintain it’s occluded relationship with adjacent teeth.

Question 13

What signs would suggest a tooth is infra-occluded?

Answer 13

Ankylosis- lack of lamina dura on radiograph.
Tooth is below the occlusal surface with adjacent teeth.
Percussion sound.

Question 14

What is the classification of infraoccluded teeth?

Answer 14

Slight- between occlusal surface and interpoximal contact, less than 2mm.

Moderate- Within occlusion-gingival margins of inter proximal contact.

Severe- Below inter proximal contact point.

Question 15

Why might a patient prematurely loose a primary tooth?

Answer 15

Trauma
Caries
Periodical pathology
Resorption by successor

Question 16

What is a balancing extraction?

Answer 16

By extraction of a tooth from the opposite side of the same arch.

Question 17

What is a compensating extraction?

Answer 17

By extraction of a tooth from the opposing arch of the same side.

Question 18

Why might you need to do a balancing or compensating extraction?

Answer 18

To maintain occlusal relationships.

Question 19

Do you require a compensating or balancing extraction if you prematurely lose an incisor tooth?

Answer 19

No, not required.

Question 20

Do you require a compensating or balancing extraction if you prematurely lose a canine?

Answer 20

Balancing extraction required because it can cause a centre line shift, maybe some medial drift of buccal segments.

Question 21

What are the consequences of losing a primary molar tooth early?

Answer 21

Mesial drift of 6’s.
More space loss with e’s than d’s
More space loss in upper than lower.

Question 22

When should 6’s be assessed for prognosis?

Answer 22

8-9 dental age

Question 23

What factors influence the impact of the loss of 6’s?

Answer 23

Age at loss
Crowding
Malocclusion

Question 24

How does age at loss of 6’s impact the dentition?

Answer 24

Upper arch doesn’t matter
Matters more in the lower arch

Lost too late- 7 doesn’t move into it’s place
Lost too early- distal drift of 5’s.

Question 25

How does crowding impact the outcome for early loss of 6's?

Answer 25

Crowding is desirable- best results for space closure. If the dentition is aligned or spaced, more likely to have spaces.

Question 26

How does early loss of a central incisor influence the dentition?

Answer 26

Lost too early- drifting of adjacent teeth Lost too late- space not closed You would aim to keep the space open with a denture, re-implant tooth.

Question 27

What is macrodontia?

Answer 27

Tooth/teeth larger than average

Question 28

What are some issues associated with macrodontia?

Answer 28

Crowding Asymmetry Aesthetics

Question 29

What is microdontia?

Answer 29

Teeth smaller than average

Question 30

What are some issues associated with microdontia?

Answer 30

Leads to spacing, linked to hypodontia.

Question 31

What aspects could make a tooth abnormally formed?

Answer 31

Dens in dente Peg shaped alterals Fused teeth Talon cusps Dilaceration Accessory cusps

Question 32

What are the most common teeth to be ectopic?

Answer 32

Third molars Upper canines First permanent molars Upper centrals

Question 33

When should you palpate the buccal canine bulge?

Answer 33

9 years onwards to feel if they're coming through. If you cannot feel them at this age, then his would warrant further investigation.

Question 34

What are the four key aspects of clinical assessment of ectopic canines?

Answer 34

Palpation of buccal canine bulge from 9 years upwards Mobility of c's and 2's Colour of c's and 2's Inclination of 2's

Question 35

What radiographic technique would you employ to determine position of the canine?

Answer 35

OPT and upper anterior oblique occlusal. - utilising parallax technique.

Question 36

What factors are associated with ectopic canines?

Answer 36

Class 2 division 2 malocclusions Absent/peg shaped upper laterals Palatal canines associated with well-aligned arches Buccal canines associated with crowding

Question 37

What are the management options for ectopic canines?

Answer 37

Prevention Extract c's and encourage improvement in position of 3 Retain 3 and observe (accept position) Surgical exposure and orthodontic alignment Extraction (surgically) Autotransplantation

Question 38

What are the management options for an ectopic first molar?

Answer 38

Reversible before the age of 8 Separator Attempt to distalise 6 Extract e

Question 39

What could be the possible causes of an ectopic upper central incisor?

Answer 39

Supernumerary- tuberculate or odontome. Trauma to primary tooth - ankylosis of primary tooth - Displacement of tooth germ - Dilaceration of root

Question 40

What is transposition?

Answer 40

Interchange in the position of two teeth.

Question 41

What teeth are most commonly transposed?

Answer 41

Upper canines and first premolar Lower canine and incisors

Question 42

What are the clinical signs of a thumb sucking habit?

Answer 42

Proclaimed upper incisors Retroclined lower incisors Localised AOB or incomplete OB Unilateral posterior cross bite due to narrow maxillary arch.

Question 43

What might a prominent labial frenum cause?

Answer 43

Midline diastema.

Question 44

Why might you want to do a balancing extraction?

Answer 44

Maintain the position of the dental centreline.

Question 45

Why might you want to do a compensating extraction?

Answer 45

Maintain the buccal occlusion.

Question 46

What is the consequence of early loss of deciduous teeth?

Answer 46

Localised crowding.

Question 47

Which primary teeth require balancing extractions?

Answer 47

c's and d's

Question 48

What conditions are associated with supernumeraries?

Answer 48

Cleft lip and palate Down's syndrome Cleidocranial dysplasia Gardner's syndrome