extractions ortho

Question 1

space requirements

Answer 1

1) relieve crowding
2) correct incisor relationship
- reduce overjet (class II)
- camouflage in class III
3) overbite correction
4) correct centrelines
5) anchorage

Question 2

how to create space

Answer 2

expansion
extraction
interdental reduction/stripping (removal of 0.25 mm enamel)

Question 3

how to expand the arch in terms of tooth movemnet (not extractions or appliances)

Answer 3

1) lateral
- molars and premolars moved laterally
2) anterior
- front teeth are proclined forward
- may be favourable if teeth are reteroclined
3) posterior
- distalise molars

Question 4

issues with non extraction anterior dimension expansion

Answer 4

anterior movement can cause bimaxillary proclination
issues with
- appearance
stability (pushing teeth out of natural balance, teeth may get moved back over time)
periodontal health (pushed out of gingiva and bone, causes recession)

Question 5

principles of extractions in ortho depends on

Answer 5

condition of teeth
location of crowding
position of teeth
appliance treatment propsed

Question 6

choice of extractions

Answer 6

incisors/canines
premolars (1st and 2nd)
molars (1st if poor prognosis, 2nd molars or 3rd for mandibular osteotomy)

Question 7

options for loss of upper central incisors

Answer 7

1) preserve space
- space maintainer
- for pontic eg bridge or implant
2) close space
- crown lateral incisor
- space may have already closed or be closed by treatment

Question 8

problems with lower incisor extraction

Answer 8

compromise occlusion
increased overjet and overbite
increased upper crowding

Question 9

why would you extract the lateral incisors

Answer 9

poor prognosis
for symmetry
severely displaced

Question 10

indications for canine extractions

Answer 10

gross displacement

quicker tx than alignment if severly displaced - f the upper first premolar and the lateral incisor are in contact

Question 11

problems with upper canine extractions

Answer 11

upper arch 
- space between 2/4 opens
2/4 not meant to sit alongside each other therefore harder to keep together
lower arch 
- poor contact between 2/4

Question 12

problems with first premolar extraction

Answer 12

may give too much space ie 7mm per tooth

possible effect on pt profole

Question 13

aims of tx

Answer 13

relief of crowdign
class I incisor and molar rx

Question 14

extraction of second premolars

Answer 14

changes anchorage balanace
- more teeth anterior to it
gives larger anchorage unit anterior
close the space behind with 6

Question 15

consequences of first molar extraction

Answer 15

extended tx due to 7s being moved into the space

Question 16

assymetric extratctions

Answer 16

within the arch or between

depends on malocclusion to change the anchorage balance