Extractions in orthodontics

Question 1

Non-extraction anterior dimension

Answer 1

Anterior movement causes bimaxillary proclination which declines

• appearance
• stability
• periodontal health

Question 2

Non-extraction posterior dimension

Answer 2

Can impact 7s and 8s if other teeth are distalise

Question 3

Third molar problems

Answer 3

In ~ 3/4 cases where teeth have not been removed there are good reasons for removing wisdom teeth in mid to late teens
BUT
All teeth must be maintained in mouth for non-extraction treatment
-3rd molars are teeth
-actually less traumatic to remove premolar prior to ortho

Question 4

Reasons for extractions in orthodontics

Answer 4

Relieve crowding
Correct incisor relationship
-reduce overjet (Class II)
-camouflage in class III
Overbite correction
Correct centrelines
Anchorage

Question 5

Principles of extractions in orthodontics

Answer 5

1. Condition of teeth
2. Location of crowding
3. Position of teeth (crowns/ apices)
4. Appliance treatment proposed (pt attitude)

Question 6

Choice of extractions

Answer 6

Anterior teeth: incisors, canines
Premolars: 1st, 2nd
Molars: 1st, 2nd

Question 7

Condition of the teeth

Answer 7

Extract teeth of poor prognosis

Question 8

Condition of the teeth

Answer 8

Extract teeth of poor prognosis

Question 9

Previous loss of upper central incisor

Answer 9

Preserve space: space maintainer for implant

Close space: crown/ build up lateral incisor

Question 10

Extraction of central incisors

Answer 10

Very rarely indicated

If poor prognosis

Question 11

Extraction of lateral incisors

Answer 11

Poor prognosis
For symmetry
Severely displaced

Question 12

Extraction of teeth close to crowding

Answer 12

Occasionally

-prefer to extract lower premolars than lower incisors

Question 13

Problems with lower incisor extraction

Answer 13

Compromise occlusion
> overjet and overbite
> upper crowding

Question 14

Extraction of canines

Answer 14

Gross displacement
Quicker treatment (than alignment if ectopic)
-can avoid appliances altogether!

Question 15

Problems with canine extractions: upper arch

Answer 15

• best teeth: aesthetics, strong and last the longest
• space between 2 and 4 opens
• poor aesthetics

Question 16

Problems with canine extractions: lower arch

Answer 16

Poor contact between 2 and 4

Question 17

Extraction of first premolars

Answer 17

Good anchorage balance

Retract anterior teeth and bring posterior teeth forward

Question 18

Problems with first premolar extractions

Answer 18

May give too much space 
-7mm per tooth
Possible effect on pt profile (upper lip will go back)
-no real evidence, just a theory
-poor treatment planning
-poor mechanics

Question 19

Extraction of second premolars

Answer 19

Changes anchorage balance

Close space from behind but larger anchorage unit anteriorly

Question 20

Extractions of first molars

Answer 20

Removes teeth of poor prognosis

Extended treatment - large spaces and large anchorage unit anteriorly?

Question 21

Extractions of second molars

Answer 21

Third molars are impacted
-96” of lower 8s erupt in good position following extraction of lower 7s
7s of poor prognosis
(Consider second molar extraction with mild crowding - 1-2mm per quadrant)
Nothing to distalise lower 6s into space so can’t move anterior teeth

Question 22

Alternatives - asymmetric extractions

Answer 22

Within the arch
Between the arches
Depending on malocclusion (to change anchorage balance)

Question 23

Edward Angle

Answer 23

Came up with molar classification
Function and aesthetics of teeth
-everyone should be able to accomodate 32 teeth

Question 24

Non-extraction vs extraction

Answer 24

Has fluctuated over the years

Now heading towards non-extraction again

Question 25

Expansion - non-extraction

Answer 25

Lateral -increasing width of arch
Anterior
Posterior

Question 26

Compromised extraction pattern

Answer 26

Taking teeth out you have to take out but wouldn’t ideally want to

Question 27

Anchorage unit decided by

Answer 27

Root surface area of the teeth

Question 28

Common alternative extraction pattern class 2 relationships

Answer 28

Upper 4s and lower 5s

Question 29

Removable appliances

Answer 29

We do not extract teeth in prep

Question 30

A patient comes in to your surgery wanting orthodontic treatment but needs some space to be created. You decide to extract all the patients 4s. What are huge advantages of extracting 4s over other teeth prior to orthodontic treatment?

Answer 30

It is not an obvious ‘front tooth’
The second premolar is similar to the first premolar in aesthetics and function.
There is usually a good contact between the first premolar and canine.
It gives a good ‘anchorage balance’, resulting in more ‘orthodontic space’.
It leaves the buccal segments with unbroken contacts from the second premolar distally.

Question 31

What must you consider when extracting second premolars?

Answer 31

Without the use of fixed appliances, there is usually a poor contact between the 6 and 4.
The first permanent molar tends to tilt and rotate.
It produces an uneven buccal occlusion.
Leads to an increased curve of spee