fixed appliances Flashcards
What is a fixed appliance and what do they consist of?
An appliance which is fixed to the teeth and cannot be removed by the patient
Consists of brackets, bands, archwires and auxiliaries and are used for precise tooth movement
What factors affect fixed appliances?
3D control
Complex tooth movements
Control of root
Less dependent on compliance
Require excellent OH
Risk of iatrogenic damage
Poor intrinsic anchorage
What factors affect removable appliances?
Simple tooth movements such as tipping
No control over root movement
Greater compliance required
Less risk of iatrogenic damage
Good intrinsic anchorage
Can be lost
When can fixed appliances be used?
Correction of mild to moderate skeletal discrepancies - camouflage
Alignment of teeth
Correction of rotations
Centreline correction
OB and OJ reduction
Closure of spaces
Creating spaces
Vertical movements of teeth
What are the components of fixed appliances?
Bracket/tube
Band
Archwire
Modules
Auxiliaries
Anchorage components
Force generating components
What are the components of brackets?
Bracket slot
Tie wings
Bracket base
What materials are used in brackets?
Metal - SS, CoCr, Ti, Au
Polymers
Ceramerics
What are bands?
SS with pre-welded attachments - can be tubes or cleats
Require space before placement - separator visit
How is bonding to teeth acquired for fixed appliances?
Composite via acid etch - brackets
Glass ionomer for molar bands
What materials can be used for archwire?
SS
NiTi
CoCr
Beta-titanium (TMA)
Composite/glass
Describe NiTi
Flexible
Applies light continuous force
Shape memory - returns to original shape and cannot bend
Higher friction than SS (disadvantage)
Describe SS archwire
Low friction
Formable into archwires and loops
Give 4 examples of force generating components
Elastic power chain
NiTi coils
Intra-oral elastics
Active ligature
What are NiTi coil springs used for?
To keep teeth apart
What are the 5 types of anchorage?
Simple
Compound
Reciprocal
Absolute
Cortical
What can be used for absolute anchorage?
Temporary anchorage devices (TADS) - non osseo-integrating mini screws
How is cortical anchorage achieved?
Cortical plates used
Maintains the intermolar width
What is needed for headgear use?
Appropriate safety mechanisms
Written and verbal instructions needed
Patient compliance
Describe post-ortho retention
Maintaining the final tooth position with a passive ortho appliance
Can be fixed or removable
Must be stressed at consent stage of tx that lifelong retention is required
Give 4 examples of features with a high relapse potential
Any from:
- diastema/space closure
- rotations
- palatally ectopic canines
- proclination of lower incisors
- AOB
- instanding upper lateral incisors
What is the retainer wear pattern for a removable pressure formed retainer?
Varies between clinicians
2 weeks full time wear except for eating and drinking
Night only thereafter
Or straight to nights only
Describe a Hawley retainer?
Labial bow to control incisors and canines
Not well tolerated in the lower arch
Give 4 examples where a fixed ortho retainer should be provided
Any from:
- spaced closure
- diastema
- proclination of lower labial segment
- periodontal cases
- ectopic canines
- instanding upper 2s
What are the risks of fixed appliances?
Decalcification
Root resorption
Relapse
How long does the average ortho case tx take?
18-24 months
How long does the average hypodontia or orthognathic case take to treat?
24-30 months
How often should routine fixed appliance adjustment take place?
Every 4-8 weeks
What initial problems may be encountered with fixed appliances?
Pain
Mucosal irritation
Ulceration
Appliance breakage
What is the role of a GDP in fixed appliances?
Continue to see pt for routine care and check ups - reinforce OHI and diet advice
Liaise with orthodontist if concerns
Make appliance safe in case of an orthodontic emergency eg - snipping of wire, removal of loose component