Anchorage

Question 1

Why are teeth extracted

Answer 1

relieve crowding
reduce an increased overjet
correct centrelines
open space for missing teeth
correct AOB

Question 2

anchorage

Answer 2

source of resistance to the reaction from active components
newton’s 3rd law

Question 3

why is anchorage important

Answer 3

gives us something to pull or push against when moving teeth
inadequate anchorage may prevent us achieving the desired tx result leading to:
- residual crowding
- residual centreline discrepancy
- residual overjet

Question 4

anchorage loss

Answer 4

extraction space closes due to forward movement of the anchor teeth rather than those teeth we wish to move
may result in:
- residual overjet
- residual crowding
- inadequate centre line correction

Question 5

how do we provide anchorage

Answer 5

other teeth in the same or opposite arch (elastics)
baseplate on removable appliance
orthodontic mini-implants
E/O
- coventional headgear
- reverse pull headgear

Question 6

why are upper 1st premolars extracted

Answer 6

overjet reduction
crowded incisors and canines
7mm space per side
ideal in Class II div I cases

Question 7

Class II Div I case tx

Answer 7

Inc overjet
well aligned lower arch
procline upper incisors
ext upper 4s
retract canines with buccal canine retractor
reduce overjet by retracting incisors with Roberts retractor

Question 8

what is the interceptive tx when extracting upper 1st premolars

Answer 8

buccally crowded upper canines
extract upper 4s as canines erupt
space maintaining appliance

Question 9

upper 2nd premolars extraction

Answer 9

mild to moderate anterior crowding
overjet reduction not required
3mm space per side

Question 10

most common lower arch extraction

Answer 10

Lower 5s

Question 11

why are lower 4s extracted

Answer 11

severe lower incisor crowding
class III
impacted lower 5s

Question 12

why are upper 2nd molars extracted

Answer 12

distalisation of first molars
mild anterior crowding
using an upper removable appliance
lower arch to prevent impaction of 3rd molars

Question 13

why are 1st molar extractions

Answer 13

space difficult to use for treating anterior crowding and/or overjet
may be lost as a result of caries

Question 14

why are incisors extracted

Answer 14

rare
upper laterals are absent or peg shaped

Question 15

why are canines extracted

Answer 15

palatally ectopic canines
- palatal canines 2% incidence