Fixed ortho appliances

Question 1

Advantages of fixed ortho appliances

Answer 1

Bodily tooth movement
Can be used in upper and lower arch easily
Individual force can be applied to every tooth
Less invasive of tongue space
Minimum palatal coverage
Not easily removed by pt
Precise 3D movement of teeth
Rotations easily fixed
Works 24hrs/7days a week

Question 2

Disadvantages of fixed ortho

Answer 2

cost
decalcification
Etching teeth destructive
High motivation for OH
Highly trained specialist training
Poor anchorage
Root resorption
relapse
Soft tissue trauma
Visually unattractive

Question 3

Advantages of removable appliances

Answer 3

Achieves block movements
easily adapted for overbite reduction
excellent anchorage
generally cheaper than fixed
less specialised training required
non destructive to tooth surface
OH easier to maintain
Shorter chairside time
tipping of teeth

Question 4

Disadvantages of removable appliances

Answer 4

can be easily removed by pt
generally only 1-2 teeth can be moved at one time
less precise control of tooth movement
rotations very difficult to correct
specialist technical staff required to construct appliance

Question 5

When do we use fixed appliances

Answer 5

alignment of teeth
correction of centreline/rotations
correction of mild to moderate skeletal discrepancies- camouflage
closure of /creating spaces
overbite and overjet reduction
vertical teeth movement

Question 6

Components of brackets

Answer 6

bracket slot
bracket base
tie wings

Question 7

Brackets materials

Answer 7

Metals- SS, CoCr, Ti, Au
polymers
ceramic

Question 8

Molar bands material

Answer 8

SS with pre-welded attachments: tubes or cleats

Question 9

What needs to be done before placing molar band

Answer 9

create space- separator visit

Question 10

What does a bracket prescription do

Answer 10

determines tip, torque and in/out control

Question 11

How are brackets and tubes bonded to teeth

Answer 11

composite via acid etch technique- light cure- micromechanical retention

Question 12

How are molar bands bonded to teeth

Answer 12

GI

Question 13

Archwire material

Answer 13

SS
CoCr
Ni-Ti
Beta-titanium
composite/glass

Question 14

Properties of Ni-Ti

Answer 14

Flexible
light continuous force
Higher friction than SS
Shape memory- returns to original shape, cannot bend

Question 15

Andrews 6 keys of normal occlusion

Answer 15

Tight contacts with no rotations
Class 1 incisors
Class 1 molars
Flat occlusal plane
long axis of teeth have slight mesial inclination except lower incisors
lingual inclination of crowns from canines to molars

Question 16

Force generating components in fixed ortho

Answer 16

Sliding mechanics: elastic power chain, NiTi coils, intra-oral elastics, active ligature
Teeth moved by utilizing energy stored in elastic or spring

Question 17

What is anchorage

Answer 17

Resistance to unwanted tooth movement

Question 18

How is absolute anchorage achieved

Answer 18

Temporary anchorage devices- non osseointegrating mini screw

Question 19

How is cortical anchorage achieved

Answer 19

cortical plates provide increased resistance to tooth movement
Maintains intermolar width

Question 20

Types of TADs

Answer 20

inter-radicular TAD
Palatal TAD

Question 21

Features with high relapse potential- need to wear retainers

Answer 21

AOB
diastema
instanding upper lateral inciors
palatally ectopic canines
proclination of lower incisors
rotations

Question 22

3 main risks of fixed appliances

Answer 22

decalcification
relapse
root resorption

Question 23

Initial problems encountered for patients when wearing fixed appliances

Answer 23

pain
mucosal irritation
ulceration
appliance breakage