Fixed Orthodontic Appliances Flashcards
What are fixed appliances?
Appliances that are fixed/bonded to teeth & cannot be removed by patient
- consists of brackets, bands, arch-wires & auxiliaries
- can performed precision movements
When do we use fixed appliances?
- correction of mild to moderate skeletal discrepancies (camouflage)
- alignment of teeth
- correction of rotations
- centreline correction
- overbite & overjet reduction
- closure of spaces / creating spaces
- vertical movement of teeth
What are Andrews six keys?
- tight approximal contacts with no rotations
- class I incisors
- class I molars
- flat occlusal plane or slight Curve of Spee
- long axis of teeth have a slight mesial inclination except lower incisors
- crowns of canines back to the molars have a lingual inclination
What are the components of fixed appliances?
- bracket/tube
- band
- archwire
- modules
- auxillaries (elastomerics or springs)
- anchorage components
- force generating components
What is normally used to fix molar bands to teeth?
GIC
What are the components of orthodontic brackets?
- bracket slot
- tie wings
- bracket base
What materials are used to make orthodontic brackets?
- metal
- polymers
- ceramics
What is torque?
buccal-lingual angulation of tooth
- based on thickness of bracket base
What is tipping?
mesial-distal angulation of tooth
How are brackets attached to teeth?
Micromechanical retention
- photoinitatior reaction using light cure composite
What archiwire materials are used?S
- stainless steel
- nichel titanium (NiTi)
- cobalt chromium
- beta-titatium
- composite/glass
When picking the material for archwire, what DMS component is essential?
SHAPE MEMORY!
Why is NiTi ideal for orthodontic archwire?
- flexible
- light continuous force
- shape memory
- higher fraction than SS
Why is Stainless Steel used for orthodontic archwire?
- working archwire to slide teeth (low friction)
What are the force generating components of fixed orthodontic appliances?
Sliding mechanics:
- elastic power chain
- NiTi coils
- intra-oral elastics
- active ligature
Teeth move by utilising the energy stored in the elastic or spring
What is the issue with elastomerics in orthodontics?
They degrade quite easily & dont tend to last very long
What is anchorage?
Resistance to unwanted tooth movement
What is compound anchorage?
Increasing anchorage by linking teeth together (done via long ligatures)
What is reciprocal anchorage?
Equal anchorage (e.g closing diastema, both incisors have equal anchorage)
How do we achieve “absolute anchorage”?
Temporary Anchorage Devices (TADS)
- non osseointegrating mini screw
What can we use to gain cortical anchorage in ortho?
- Transpalatal arch
- Nance arch
How is intermaxillary anchorage achieved in orthdontics?
Bonding upper & lower arch with elastics
- different malocclusions have different band placements
What is the function of retainers?
maintaining the final tooth position with a passive orthodontic appliance
What malocclusion features have high relapse potential?
- diastema/space closure
- rotations
- palatally ectopic canine
- proclination of lower incisors
- anterior open bite
- instanding upper lateral incisors
Name a removable retainer:
Hawley retainer (1920s)
What malocclusion features typically require fixed bonded retainer after fixed ortho is finished?
- space closure
- diastema
- proclination of lower labial segment
- periodontal cases
- ectopic canines
- instanding upper 2s
What are the main risks with fixed appliances?
- decalcification
- root resorption
- relapse
- damage to enamel
What do patients typically complain about during fixed ortho treatment?
- pain
- mucosal irritation
- ulceration
- appliance breakage
What is a GDPs role in fixed orthodontic treatment?
See patient for routine care & check ups
- reinforce OHI & diet advice
- liaise with orthodontist if concerned
- make appliance safe in orthodontic emergency
