Extractions in orthodontics Flashcards
Give an account of the advantages and disadvantages of different extraction patterns; Discuss the merits of the extraction of each tooth in the arch; Understand the difference between ideal and compromise extraction.
Non-extraction anterior dimension
Anterior movement causes bimaxillary proclination which declines
- appearance
- stability
- periodontal health
Non-extraction posterior dimension
Can impact 7s and 8s if other teeth are distalise
Third molar problems
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
Reasons for extractions in orthodontics
Relieve crowding Correct incisor relationship -reduce overjet (Class II) -camouflage in class III Overbite correction Correct centrelines Anchorage
Principles of extractions in orthodontics
- Condition of teeth
- Location of crowding
- Position of teeth (crowns/ apices)
- Appliance treatment proposed (pt attitude)
Choice of extractions
Anterior teeth: incisors, canines
Premolars: 1st, 2nd
Molars: 1st, 2nd
Condition of the teeth
Extract teeth of poor prognosis
Condition of the teeth
Extract teeth of poor prognosis
Previous loss of upper central incisor
Preserve space: space maintainer for implant
Close space: crown/ build up lateral incisor
Extraction of central incisors
Very rarely indicated
If poor prognosis
Extraction of lateral incisors
Poor prognosis
For symmetry
Severely displaced
Extraction of teeth close to crowding
Occasionally
-prefer to extract lower premolars than lower incisors
Problems with lower incisor extraction
Compromise occlusion
> overjet and overbite
> upper crowding
Extraction of canines
Gross displacement Quicker treatment (than alignment if ectopic) -can avoid appliances altogether!
Problems with canine extractions: upper arch
- best teeth: aesthetics, strong and last the longest
- space between 2 and 4 opens
- poor aesthetics
Problems with canine extractions: lower arch
Poor contact between 2 and 4
Extraction of first premolars
Good anchorage balance
Retract anterior teeth and bring posterior teeth forward
Problems with first premolar extractions
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
Extraction of second premolars
Changes anchorage balance
Close space from behind but larger anchorage unit anteriorly
Extractions of first molars
Removes teeth of poor prognosis
Extended treatment - large spaces and large anchorage unit anteriorly?
Extractions of second molars
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
Alternatives - asymmetric extractions
Within the arch
Between the arches
Depending on malocclusion (to change anchorage balance)
Edward Angle
Came up with molar classification
Function and aesthetics of teeth
-everyone should be able to accomodate 32 teeth
Non-extraction vs extraction
Has fluctuated over the years
Now heading towards non-extraction again
Expansion - non-extraction
Lateral -increasing width of arch
Anterior
Posterior
Compromised extraction pattern
Taking teeth out you have to take out but wouldn’t ideally want to
Anchorage unit decided by
Root surface area of the teeth
Common alternative extraction pattern class 2 relationships
Upper 4s and lower 5s
Removable appliances
We do not extract teeth in prep
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?
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.
What must you consider when extracting second premolars?
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
