Location in arch such that space gained by Xn utilized for correction of both anterior and posterior segments.
Bimaxillary dento alveolar protrusion.
Riedel- treatment time is reduced.
Extractions in orthodontics /certified fixed orthodontic courses by Indian dental academy
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Increased ability to move teeth under better control:
ever-expanding choice of extraction.
Factors affecting choice of extraction
1. Treatment objectives
2. Type of malocclusion
3. Esthetics (large chin button, prominent nose)
4. Growth pattern.
5. Conditions of teeth.(caries, multifilled teeth,
impacted, ectopic, severe rotation)
6. Health of supporting tissues.
Facial profile alteration:
Maxi retraction of U&L anteriors: 4s (laterals)
Lesser retraction in lower face: U4s and L5s
Less overall retraction: 5s or 6s.
Deep anterior overbite:
Closer.( Mechanically easier to level, as spaces are
closed). incisors – min time and effort.
5 or 6 Xn. Accentuate the curve of Spee.
GRABER: Removal of 5s in mandibular arch preferable.
‘.’ reduces the tendency of relapse of openbite &lingually
inclined incisors seen occasionally with Xn of 4s.
Erupts before any other post teeth, after 6.
Eruptive sequence : Xn at proper time.
Strategically located close to the incisors.
Center of each half of arch .’. Ant & post crowding.
Protraction of molars not required.
4 Xn adequate anchorage for retraction of 6 teeth.
Contact b/w canine and 2nd premolar satisfactory.
Indications for I st premolar extraction:
1. Convex profile with
2. Class II div I with deep
3. Class I with severe
4. Class I with bimaxillary
Indications for I st premolar extraction.
Extraction of 2nd premolars:
1.mild degree of crowding & excellent profile.
2.No crowding and fullness of lips.
Begg: unless carious or poorly formed.
Nance: Ist person.Mild discrepancy.
Avoids dished-in-face & less tendency for relapse.
DEWEL: Xn creates more space in borderline cases,
closed by reducing the anchorage value of buccal
U4 more esthetic than 5
Contact b/w 4 and 6 tended to stay closed.
Reduced possibility of buccal/lingual furrows
in Xn site ‘.’ of rapid closure.
Closure of ant open bite, by reducing post
De CASTRO: 3 independent segments.
5s Xed only post segment shortened.
4s Xed, both segments shortened- functional
integrity of the dentition.
INDICATIONS FOR 2ND PREMOLAR EXTRACTION
1.Good profile+mild crowding
2.flat profile+moderate crowding
3.Class II div 1 on skeletal class I
4. Mild Class III inter-arch
relation+mild crowding in U arch.
6. Grossly destructed/heavy restn.
7. Abnormal root morphology.
8. Open bite.
1. Original facial contours
retained without reduction of
Extraction of 2nd premolars:
U 4 more esthetic along side canine.
Lesser tendency for extraction space to open in L arch.
Less possibility of buccal/lingual furrow in Xn space.
Easy correction of Class II molar correction to Class I
Not provide adequate space in the ant region.
5 & 7 may tip in the Xn space.
Deepening of bite.
Carious- beyond restoration
RCTreated, - than a perfectly good premolar.
Multi filled teeth- crown.
Premature Xn of 6, to preserve symmetry.
Facial considerations: large chin buttons&/ prominent
(rationale: farther back less facial change)
Open bite cases.
Not to allow U7 locked behind L7.
Horizontal elastics – until danger of locking has
Mesially inclined 7, lesser degree of anchor bend.
Wilkinson’s Extraction: 1942
8 ½ to 9 ½ yrs. Extraction of all Ist molars.
•Additional space for eruption of 8s.
•Crowding of lower arch minimized.
Class II div 1 with perfect lower arch alignment but
growth expectation inadequate.
Class II div 1 active growth over. Pt non
Class II div 1 with good lower arch over basal bone,
with some growth expectation.
Class II div 1 with mild open bite.
Problems with Xn of 4s:
Tipping, opening of space (5 small to fill the
Mesial tipping of 6, hanging palatal cusp
Avoided with 6 Xn.
Good molar relation.
U 4 occlude with L4
8s erupt normally.
Min patient cooperation
Tuberosity not crowded.
Results similar to nonext.
Rx duration is reduced.
David W.Liddle- AJO 1977
Malocclusion: potential force by developing 7,8.
Xn of 7s to intercept this forward force.
4 Xn: treating the effect and not the cause.
10-12mm of space :satisfies arch length problem, not
apparent when patient smiles.
91% 7 Xn.
6 move distally in response to pressure.
Over compressed CT fibers- move 3 &4 to a more
ADVANTAGES AND INDICATIONS
Disimpaction of 3rd molars, faster eruption
Prevention of “dished-in” at the end of facial
Prevention of late incisor imbrication
Facilitation of 1st molar distalization
Distal movement only as needed to correct the
Fewer “residual”spaces at the end of Rx
Less likelihood of relapse
Good functional occlusion
Good mandibular arch form
Xn 7 - caries, ectopic, rotated.
Mild – moderate discrepancy with good profile.
Crowding in tuberosity area ,with a need for distal
movement of 1st molar.
Lehman - preconditions
8 in favorable angulation 15-30*angle to the long
axis of the 1st molar.
Normal in size/shape & root area is sufficient w.r.t
No congenitally missing teeth.
Too much tooth substance removed in Cl I mal
occlusion with mild crowding.
Location far from area of concern.
No help in correction of A-P discrepancy without
patient cooperation .
Possible impaction of 3rd molars even with 2nd molar
Unacceptable positions of erupted 3rd molars –
second, late stage of fixed therapy.
9-20% missing 3rd molars.
3rd molar crowns completely formed, Xn
before roots begin to develop
30*to the occlusal plane
3rd molars in close proximity to 2nd molardrift.
Halderson, Huggins, Lehman and Smith.
Before radiographic evidence of root formn.(12-14yrs)
Consensus opinion: as soon as 2nd molar erupts.
Xn to prevent lower anterior
Distal movement of 6,7– impaction of
Xn of 8 before retracting.
1st or 2nd molars are extracted.
Mandibular incisors- therapeutic value
1st sign of incipient malocclusion
Difficult to treat as they relapse easily.
Not a new idea.
Riedel : Xn of 2 lower
Incisors-arch form without
Expn of intercanine width
Occlusal planes, abnormal overbite
For mandibular incisors:
Extreme crowding /
Gingival recession & loss of
overlying bone on labial
Lateral incisors severely # in
Rarely-discrepancy in sizes of
U & L incisors themselves, 1
incisor can be removed.
Reidel- Rx time reduced.
min facial change.
General arch form is
maintained – greater stability
Retention period- less
Anterior segments can be
retracted readily if need be.
Immediate solid tooth support
of entire buccal segments.
Easy reduction of overbiteintrusion, reshaping
Mechanotherapy is simplified.
Space closure quick.
Reopening of space . Central Incisor.
Danger of creating a tooth size discrepancy.
Reidel- 2 mandi incisors Xed to maintain
1 incisor Xn- deepbite- if normal tooth size
relationship is present before Xn.
Color difference of canine.
Unfavorable impaction of U incisor.
Bu/Li blocked out lateral, with good contact b/w
central and canine.
Congenital missing of 1 lateral incisor
Gardiner et al:
U crowding, mesial displacement of root
apices of U3 - Xn of lateral incisor.
Incisor Xn rare.
Possibility must always be considered.
Careful planning with diagnostic setup
Not extracted. Profile.
Long path of eruption.
Impossible to bring in alignment.
Gross displacement Bu/Li
4 in contact with 2 & does not show palatal cusp.
Decision : position of apex.
Relation b/w root surface area and Xn site selection
upon incisor retraction.
Larger the root surface area, greater the resistance to
Location of the Xn site Root surface area.
Predict incisor retraction.
Should be considered in diagnosis, so that a desired
Rx goal for the final position of incisors within the
facial profile can be achieved.
Orthodontic treatment may include extractions
of any tooth in the arch.
Based on sound diagnosis, treatment objectives.
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