Fixed Appliances

Question 1

definition of fixed appliance

Answer 1

appliance which is fixed to teeth and cannot be removed by patient

consists of brackets, bands, arch wires and auxillaries

Question 2

features/pros/cons of fixed appliances

Answer 2

Pros:
 3D control
 Complex tooth movements
 Control of root
 Less dependant on
compliance

cons:
 Requires excellent oral
hygiene
 Risk of iatrogenic damage
 Poor intrinsic anchorage

Question 3

features/pros/cons of removable appliances

Answer 3

simple tooth movements - tipping/tilting

pros:
- less risk of iatrogenic damage
- good intrinsic anchorage

cons:
- greater compliance required
no control over root movement
- can be lost

Question 4

when do we use fixed appliances?

Answer 4

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

Question 5

list andrews 6 keys

Answer 5

• tight approximal contacts with no rotations
• class 1 incisors
• class 1 molars
• flat occlusal plane or slight curve of spee
• long axis of the teeth have a slight mesial inclination (except lower incisors)
• crowns of canines back to molars have a slight lingual inclination

Question 6

list fixed appliance components

Answer 6

• bracket/tube
• band
• arch wire
• modules
• auxiliaries
• anchorage components
• force generating components

Question 7

what components make up a bracket?

Answer 7

• bracket slot
• tie wings
• bracket base

Question 8

what materials used to make brackets?

Answer 8

• metal: SS, CoCr, Ti, Au
• polymers
• ceramics

Question 9

What are bands? (in fixed appliances)

Answer 9

SS with pre welded attachments
- tubes or cleats

• require space before placement (separator visit)

Question 10

what factors are determined by bracket prescription?

Answer 10

• tipping movement
• torque
• in/out control

Question 11

what materials used for bonding to teeth with fixed appliances?

Answer 11

• composite, acid etch
  used for brackets and tubes
• GI used for molar bands

Question 12

most common materials used for arch wires?

Answer 12

• SS, NiTi

Question 13

Features of NiTi used in arch wire

Answer 13

• flexible
• applies light continuous force
• shape memory (returns to original shape, cannot bend)
• higher friction than SS

Question 14

features of SS arch wire

Answer 14

• low friction
• formable:
  can make arch wire bends and loops

Question 15

list force generating components in fixed appliances

Answer 15

• sliding mechanics:
  elastic power chain
  NiTi coils
  intraoral elastics
  active ligature
• teeth move by utilising the energy stored in elastic or spring

Question 16

what is this?

Answer 16

elastomeric chain

Question 17

what is this?

Answer 17

NiTi coil springs

Question 18

what is this?

Answer 18

intraoral elastics

Question 19

what types of anchorage are there?

Answer 19

• simple
• compound
• reciprocal
• absolute
• cortical
• inter maxillary

Question 20

what type of anchorage is shown here?

Answer 20

simple

Question 21

what type of anchorage is shown here?

Answer 21

compound

Question 22

what type of anchorage is shown here?

Answer 22

reciprocal

Question 23

what kind of device is used for absolute anchorage?

Answer 23

• temporary anchorage device (TADS):
  non osseointegrating mini screw
• major development in orthodontics:
  anchorage control
  tooth movement mechanics

Question 24

what temporary anchorage devices (TAD) are shown here?

Answer 24

(left) inter-radicular TAD

(right) palatal TAD

Question 25

what is cortical anchorage?

Answer 25

- cortical plates provide greater resistance to unwanted tooth movement - maintains intermolar width

Question 26

what type of anchorage is shown here?

Answer 26

inter maxillary anchorage

Question 27

what is a retainer?

Answer 27

- passive orthodontic appliance that maintains final tooth position - appliances designed to prevent relapse: fixed removable

Question 28

what is very important to let the patient know at the consent stage of orthodontic treatment?

Answer 28

- lifelong retention required to prevent relapse

Question 29

list features that have high relapse potential

Answer 29

- diastema/space closure - rotations - palatally ectopic canines - proclination of lower incisors - anterior open bite - instancing upper lateral incisors

Question 30

list some types of removable retainers + features

Answer 30

- pressure formed retainers - (clear overlay retainers): variety of materials and thickness can include prosthetic tooth for aesthetics well tolerated

Question 31

what retainer wear patterns are normally used?

Answer 31

- 2 weeks full time wear except for eating and drinking, night time wear afterwards or - straight to nights only

Question 32

what retainer is this and how does it work?

Answer 32

- Hawley retainer - labial bow to control incisors and canines - not well tolerated in the lower arch

Question 33

in what clinical situations are fixed orthodontic retainers used?

Answer 33

- space closure - diastema - proclination of lower labial segment - periodontal cases - ectopic canines - instanding upper 2's - some orthodontists use them for all cases

Question 34

important things to know for bonded wire retainers?

Answer 34

- requires careful monitoring and ID cleaning - ensure composite attachments intact and sound - refer back to orthodontist if problems

Question 35

risk/benefits of fixed appliances

Answer 35

- decalcification - root resorption - relapse - enamel wear

Question 36

give some timescales for treatment of orthodontic cases

Answer 36

- average case = 18 - 24 months - hypodontia = 24 - 30 months - orthognathic = 24 - 30 months

Question 37

what are some initial problems encountered with fixed appliance treatment in patients?

Answer 37

- pain - mucosal irritation - ulceration - appliance breakage

Question 38

role of GDP in ortho cases

Answer 38

- routine care and check-ups reinforce OHI and diet advice - liaise with orthodontist if concerns - make appliance safe in case of an ortho emergency: e.g cut jaggy wire, removal of loose components