removable appliances in ortho

Question 1

disadvantages of removable appliances

Answer 1

• removable (not in all the time!) – can also be damaged, lost ect
• can only tip teeth (only one point of contact)
• affects speech
• poorly tolerated in lower arch
• intermaxillary traction not possible (no elastics can be used between md/mx)
• inefficient for multiple tooth movements

Question 2

designing a removable applaance parts

Answer 2

active components
retentive
anchorage
baseplate and biteplates

Question 3

active components

Answer 3

ie moving the teeth

1) springs
- palatal sprigns
- buccal springs
2) screws
3) elastics

Question 4

force of springs depends on

Answer 4

thickness of wire (increasing diameter increases force sig)
length of wire (increasing length decreases force - inverse proprtioanl)
amount of deflection

Question 5

palatal finger spring

Answer 5

0.5-6mm wire
coil near acrylic
used to disalist canine

Question 6

types of springs

Answer 6

closed - when activated will open

open

Question 7

quarter turn of a screw is

Answer 7

0.2mm

Question 8

indications for scews

Answer 8

moving blocks of teeth eg correcting class 3 and expanding the arch 
can move teeth which are being used for retention

Question 9

retentive components

Answer 9

posterior - adams cribs (MB and DM undercuts)

anterior - C claps, southend clasp

Question 10

anchorage

Answer 10

stopping unwanted tooth movement
- spread the equal and opposite force out over multple teeth , the wanted tooth movement will be greater than the force on the opposite teeth

Question 11

how to not lose anchorage

Answer 11

light forces
only move one tooth
large anchor unit
headgear

Question 12

problems with headgear

Answer 12

cooperation

safety

Question 13

problems with eye injury

Answer 13

high risk of infeciton
excellent culture medium
difficult to control with Ab
sympathetic opthalmaitis (in opposite eye)

Question 14

baseplate

Answer 14

• connects components
• carries passive wirework
• additional anchorage on palate
• carries biteplanes

Question 15

biteplane types and what they do

Answer 15

anterior - flat, opens bite distally therefore leading to posterior eruption
posterior - maintains class 2 correction and position of anterior teeth of reduced overbite
maintins functional appliance treatment, stops interfere of lower incisiors

Question 16

cases to treat removable appliances

Answer 16

disimpaction of 1st molars

• class III – anterior crossbite
• posterior crossbite (with associated mandibular displacement) in mixed dentition or expansion prior to functional appliances
• space maintenance
• overbite correction

Question 17

what can removable applianes be used to treat

Answer 17

correct anterior crossbite in mixed dentition
screw appliance to expand upper arch
retraction of permanent molars