Extractions in Orthodontics

Question 1

4 reasons space creation is needed

Answer 1

relieve crowding
correct incisor relationship- overjet, overbite
correct molar relationship
compensate for skeletal discrepancies

Question 2

5 methods by which space is created

Answer 2

Extractions
Growth- functional appliance
Interdental enamel reduction
Distal movement
Expansion

Question 3

8 reasons teeth may be extracted

Answer 3

caries/pulp pathology
trauma
infra-occlusion
ectopic permanent teeth
supernumerary teeth
hypodontia
preparation for alveolar bone graft- 
centre line shift

Question 4

Define overjet

Answer 4

horizontal distance between upper and lower anteriors

usually 1-3mm

Question 5

define overbite

Answer 5

vertical overlap of the upper incisors over the lower incisors >30% covered

Question 6

Define the term ‘functional applaince’

Answer 6

appliances which alter forces of muscle function, tooth eruption and growth to correct a malocclusion
Fixed or removable
works by posturing the mandible forwards in growing patients

Question 7

Which type of malocclusion does a functional appliance correct

Answer 7

Class II

correct an increased over jet

Question 8

What is the most common fixed appliance used

Answer 8

twin block

Question 9

List 3 techniques in which distal movement can be achieved

Answer 9

headgear
non-compliance distaliser
Implants (TAD)

Question 10

When would headgear be used?

Answer 10

when little space is require - 2-3mm each side- as extraction would cause too much space
in addition to extraction if more space is required

Question 11

How does headgear work?

Answer 11

pull posterior teeth back using the back of the head as anchorage

Question 12

What is required for headgear to be effective?

Answer 12

Patient compliance

Question 13

How does a non-compliance distaliser work?

Answer 13

Maxillary molar distaliser
growing and non-growing patients
no compliance needed

Question 14

What does TAD stand for and how does it work?

Answer 14

Temporary anchorage device
miniscrews placed in alveolar bone under LA which can be used to provide orthodontic anchorage
these are removed at the end of the treatment

Question 15

When would it be useful to use TADs?

Answer 15

when large/difficult tooth movement are required

Question 16

2 methods expansion can be created and describe them

Answer 16

Quadhelix- expand dental arches, fixed slow expansion appliance,
RME- Rapid maxillary expansion by opening midline suture, fixed, patient can adjust

Question 17

How does expansion work in orthodontics?

Answer 17

Widens maxilla/expand arches

open midline suture and expand upper arch

Question 18

What is interdental enamel reduction and how is this carried out?

Answer 18

removing enamel mesidal and distal of teeth to create space

with an abrasive strip

Question 19

What should teeth be treated with following interdental enamel reduction?

Answer 19

F-

Question 20

What does the term ectopic teeth mean

Answer 20

eruption disturbance

tooth does not follow its usual course

Question 21

Define hypodontia

Answer 21

Congenitally missing teeth

Question 22

Define centre line shift

Answer 22

midline of upper and lower do not meet- either to left or right

Question 23

Define infra-occlusion, what causes it and which teeth are mainly affected

Answer 23

Teeth that are fixed in position whilst remaining teeth continue to erupt due to ankylosis of the tooh
mainly affects primary molars

Question 24

Define ankylosis and why is this a problem

Answer 24

Fusion of the tooth to bone preventing eruption and orthodontic movement

Question 25

Define supernumerary teeth and which teeth are most commonly affected

Answer 25

Duplications of teeth 2nd lateral incisor (mesiodens) molars and premolars

Question 26

Define transitional incisor crowding

Answer 26

transition from primary to permanent dentition- incisor crowding in mixed dentition

Question 27

which tooth is most likely to be ectopic?

Answer 27

3's

Question 28

Which age should 3's be palpable and what should be done if not palpable?

Answer 28

9 | if not palpable at 10- x rays

Question 29

What technique is used in a radiograph for ectopic teeth?

Answer 29

parallax--S.L.O.B

Question 30

Which teeth are most likely to be infra-occluded?

Answer 30

D's and E's

Question 31

Which teeth are most likely to be congenitally missing?

Answer 31

5's so extract E's

Question 32

Which teeth would most likely extracted to correct centre line shift?

Answer 32

C's

Question 33

3 reasons why A's and B's would be extracted

Answer 33

trauma ectopic permanent tooth caries

Question 34

5 reasons why C's would be extracted

Answer 34

``` caries trauma ectopic permanent tooth correct centre line shift transition incisor crowding ```

Question 35

Which tooth is most likely to be extraced if transitional incisor crowding?

Answer 35

C's

Question 36

4 reasons D's may be extracted

Answer 36

caries infra-occlusion ectopic permanent tooth hypodontia

Question 37

5 reasons E's may be extracted

Answer 37

``` caries infra-occluded impacted 6's hypodontia- missing 5's ectopic 5 so extract E ```

Question 38

Which permanent teeth are mainly extracted for ortho?

Answer 38

premolars --4's

Question 39

Which permanent tooth would be extracted to correct an overjet?

Answer 39

4's

Question 40

If U6 is extracted why would you consider extracting L6?

Answer 40

to prevent over eruption of the L6

Question 41

3 reasons why a 6 maybe extracted for ortho and not premolars

Answer 41

heavily restored MIH- hypoplastic poor long term prognosis- extensive caries

Question 42

What can occur of 6's are extracted too early and what age would this be?

Answer 42

mainly for lower arch <8 premolar may drift distally into this space, rotate or tilt and then long need for fixed appliances

Question 43

what can occur is 6's are extracted too late and what age would this be?

Answer 43

>10 | 7 may be in later stages of eruption and may then tip mesially and rotate and may not come forward enough

Question 44

what are disadvantages of extraction treatment (ortho)?

Answer 44

affects TMJ

Question 45

what does non-extraction treatment cause?

Answer 45

poor stability

Question 46

What is extraction choice based on?

Answer 46

crowding/overjet