7 - Treatment Planning and Extractions in Orthodontics Flashcards
Treatment planning and extractions of permanent teeth
When do we extract permanent teeth for orthodontic reasons? - 2
Bottom left pic - class 2 occlusion with large overjet - if want to reduce overjet can make space by removing eg U4s
Bottom right - class 3- main need space in lower arch to allow it to be retracted
Choice of teeth for extractions
Depends on : (4)
Condition of tooth -> Eg tooth with carious, very hypoplastic, heavily retried , root filled or trauma or poor prognosis
Position of crowding -> upper arch crowding commonly in canine region- as upper canine is last tooth to erupt
Upper arch - Back of arch may see molar stacking on DPT (6,7,8 on top of each other as seen DPT UR region )
Lower arch - impaction of lower 7/8 region
Crowding - clinically and DPT
Position of teeth -> any ectopic teeth? Most commonly upper canine - eg bottom clinical photo ectopic canine so would extract this. May be seen palatally on DPT as ectopic and unerupted
4mm crowding - half premolar width
Moderate more than 4mm more than half premolar
Severe - more than whole premolar width
Extraction patterns
What are the extraction patterns for:
Class I
Class II
Class III
Severe crowding - tend to extract 4s
Less severe -extract 5s
for class I - we follow this So don’t interrupt anterior posterior relationship
Treatment planning for extractions
List the 3 steps we follow in the correct order :
- Lower arch
- space required?
- to relieve crowding?
- Centre line correction?
- consider anchorage? - Upper arch
- space required?
- to relieve crowding?
- Centre line correction?
- consider anchorage? - Once extractions chosen, consider type of tooth movement
Extraction cases need bodily tooth movement with fixed appliances to prevent gross tilting
Consider anchorage? – When the whole of the extraction space is needed to relive the crowding, you can’t allow the posterior teeth to move forward into the space -> This is a high anchorage case.
If not all the space is needed, then the molars can be allowed to move forward-> This is a low anchorage case.
Extraction of 4s
Indications
Shortens duration -> If 5s extracted then the 4s would need to be moved back to open space which takes longer
Case example of extraction of 4s
Click answer
Mixed dentition
Lower arch - retained Es, severe crowding of lower canine with a centre line shift
Will need to extract 4 on either side
Upper arch- no space at all for the canine - unerupted and buccally placed
Helpful to extract 4s, hold space, allow 3s to erupt and then align
Class 1 case
Severe crowding in upper and lower arches in canine region
Case example of extraction of 4s
- Lack of space for unerupted canine upper arch
- lack of space for buccal displaced canine lower arch
Extracted 4s, held the space whilst upper canines erupted
Fixed appliance
Case example extraction of 4s
Class 1 skeletal pattern
Occlusion- edge to edge - mild class III incisor relationship
Lower arch- mild crowding in canine and incisor region and back of arch. If class III - need to extract as far forward in lower arch so extract L4s
Upper arch - severe crowding of upper canine - lack of space for these canine so need to extract U4s
Need space in lower arch to bring lower labial segment back slightly and upper labial segment forward as class III incisor relationship
Upper arch:
Retract canines
Retract lower labial segment slightly
Bring upper labial segment forward a little
Align arches
Now class 1 incisor relationship and class 1 molar relationship
When do we extract U4s ONLY?
Extraction of 5s
Indications
- Indicated where the crowding is mild to moderate – The width of a 5 is smaller than that of a 4. This is why they are extracted in cases with less severe crowding. Sometimes the 5 is rotated. In patients with spacing, this can be left alone, if it helps to filled the arch.
- If 5s have poor prognosis - eg hypoplastic- or palatally/lingually displaced
- Will need fixed appliances to retract 4s,3s etc
- Extracting the 5s will alter the anchorage balance – The movement of 4 teeth is anchored by a single tooth (6), which may produce a reciprocal effect on the upper 6.
Case example of extraction of 5s
See answer
Class I incisors and molars
Mild crowding in upper and lower arch
On X-ray some crowding at back of arch
Option 1 - align teeth without extractions
Option 2- extract 5s top and bottom
Extraction of upper 4s and lower 5s
Indications
OJ = overjet
Case example of extraction of upper 4s and lower 5s
Skeletal 2
Incompetent lips
Increased overjet
Arches:
Upper: Moderate crowding in upper arch -> need space in upper arch to relieve this and correct overjet
Lower: mild crowding but short of space towards back of the arch.
Would be helpful to extract 5s - dont need much space but upper arch need space to relieve crowding and reduce overjet so U4s
Will help correct molar relationship- half unit class II atm with large overjet - as seen on EO photograph
Extractions of upper 5s and lower 4s
Extraction of 6s
Indications
Disadvantages
Only if 6 is poor prognosis - heavily restored, carious or severely hypoplastic
Extraction of 6s
When do we ideally want to extract the 6?
Want to extract before 7 has erupted:
Early extraction of 6s before 7s have erupted - on DPT calcification of crown of 7 as far as root bifurcation (shown on DPT), 7 will erupt into forward position where 6 was
If after 7 has erupted - need fixed appliances:
Upper arch is reasonable but lower arch should be avoided but if is then need fixed appliances
SUMMARY:
FIRST BP - > when class I case
SECOND BP-> when crowding and thinking will need to relive, or class II or III to correct anterior posterior relationship - if pt has malocclusion would want to wait and hold on to 6s until 7s erupt
Third BP - if 6 is lost, then might consider losing U6 if also poor prognosis or crowding in that area
But if u6 lost not good idea to take L6 out- upper arch 7 comes forward nicely but not the case in lower
Extraction of 7s
Indications
Extraction of 8s
NICE GUIDELINES
Canine and Incisor extractions
Indications
Canine it’s important in occlusion so try not to extract - only if its in a very ectopic position eg horizontal unerupted
Incisors - important for aesthetics so avoid extracting
If there is traumatic loss of upper central incisor what do we do from an ortho view
Hold onto that space and then restorative treatment eg bridge or implant long term
If have crowding - could move canines into lateral incisors spaces if there’s a gap there already
Missing upper lateral incisor
can use space and move canine into lateral incisor position- would disguise restoratively
Extraction of lower incisor tooth:
Often tempting if lower incisor crowding so may consider in an adult. But there are 2 sequelae:
- May increase crowding of upper incisors or result in an increase in overjet
- May end up with 3 crowded lower incisors
- There is a need for a bonded retainer
Would not do this in a teenager
Early loss of deciduous teeth
Effect depends on: -3
Loss of deciduous incisors
Can see dilacerated upper incisor in radiograph
Loss of deciduous canines
Loss of deciduous molars
Loss of D:
Loss of E:
Deciduous Ds and Es are natural space maintainers - so try to maintain if possible and only extract if prognosis extremely poor and cannot be restored
Space maintainers
What is it?
Uses
Disadvantages
Must get OH and diet under control - as can cause caries
Use it for - Class I well aligned and early loss of E
Summary
