Fixed Ortho Flashcards
What is the definition of Fixed appliances?
- Appliance which is fixed to teeth and can’t be removed by pt
- Consists of brackets, bands, archwires and auxillaries
- They are precision tooth movers
Compare fixed appliances and removable appliances
Fixed
- 3D control
- Complex tooth movements
- Control of root
- Less dependent on compliance
- Requires excellent oral hygiene
- Risk of iatrogenic damage
- Poor intrinsic anchorage
Removable appliances
- Simple tooth movements, tipping
- No control over root movement
- Greater compliance required
- Less risk of iatrogenic damage
- Good intrinsic anchorage
- Can be lost
When do we use fixed appliances?
- Correction of mild to mod skeletal discrepancies (camoflauge)
- Alignment of teeth
- Correction of rotations
- Centreline correction
- Overbite and overjet reduction
- Vertical movement of teeth
- Closure of spaces / creating spaces
What are out treatment goals? 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 slight mesial inclination except lower incisors
- Crowns of canines back to molar have lingual inlcination
What are the fixed appliance components?
- Bracket / tube
- Band
- Archwire
- Elastomeric Modules
- Auxillaries (little springs or elastomerics)
- Anchorage components
- Force generating components
What are the brackets made of? What are its components
- Stainless steel most common
- Polymers or ceramics can also be used
- Consist of
- bracket slot
- Tie wings
- Bracket base
What are the bands? What is needed prior placement?
- Stainless steel with pre welded attachments
- Can also include tubes or cleats
- Require space before placement
- Need a separator 1-2 weeks before band placement - gives 1mm space around contact point
What does torque movement do?
- Buccal lingual tipping (angulation) of root of tooth
How are the brackets bonded to teeth? What material is used? What reaction is it? What type of retention is it?
- Composite via acid etch technique
- Used for brackets and tubes not bands
- Photo initiation reaction using light cure 440-480nm wavelength of light
- Micromechanical retention
What material are the molar bands bonded to teeth with?
- Glass ionomer
What materials of archwires are there?
- Stainless steel used after NT working up the way hardest
- Nickel titanium (shape memory) - gives light continuous force
What are some properties of Nickel Titanium wire?
- Flexible
- Light continuous force
- Shape memory so returns to original shapes and cannot bend
- Higher friction than SS but using this small of a diamter doesnt usually create issues
What is meant by cannot bend ?
- Cannot form a loop within the wire
- bend will not stay
What are some properties of stainless steel wire?
- Lower friction so tends to slide teeth easier
- Formable so archwire can bend and loops
Why is bumper tubing used?
- To protect flimsy wire that could be knocked out of place if tooth contacts it
- Gives more rigidity
Give some force generating components ? How do the teeth move using these?
Sliding mechanics
- Elastic power chain
- NiTi coils
- IO elastics
- Active ligature
- Teeth move by utilising energy stored in the elastic or spring
- Need to be seen frequently to continue elastomeric changes
What are NiTi coil springs used for?
- Push teeth apart
What are the anchorage considerations?
- Resistance to unwanted tooth movement
- Newtons 3rd La : Every forces has equal but opposite reactionary force
What is compound anchorage
- Use long ligatures over more than one tooth, this increase in root surface allows for more favourable tooth movement
What is absolute anchorage?
- Temporary anchorage devices (non osseointegrating mini screw)
- Gives anchorage control
- Can be buccal or palatal
What is reciprocal anchorage?
- Type of anchorage when two units of teeth move towards each other with equal distance
What is Cortical anchorage
- Cortical plates provide increased resistance to tooth movement
- Maintains intermolar width
How is intermaxillary anchorage utilised?
- Class 3 or Class 2 elastics
What is function of retainers?
- Maintain final tooth pos with a passive orthodontic appliance
What features have a higher relapse potential?
- Diastema / space closure
- Rotations
- Palatally ectopic canines
- Proclination of lower incisors
- AOB
- Instanding upper lateral incisors
Give a different option of retainer other than thermoplastic?
- Hawley retainer
What are the variety of clinical situations where you would chose a fixed retainer?
- Spaced closure
- Diastema
- Proclination of lower labial segment
- Periodontal cases
- Ectopic canines’
- Instanding upper 2s
What can go wrong with fixed reatiners?
- Comp can debond and tooth can move
- Caries
- Poor oral hygiene
- If become active can cause teeth excluded from arch
3 Main risks with fixed appliances
How to prevent
- Decalcification
- Root resorption
- Relapse
Careful case selection
Monitoring
Pt compliance and motivation
What initial problems can a pt encounter at start of ortho?
- Pain
- Mucosal irritation
- Ulceration
- Appliance breakage
Role as GDP in ortho pts
- OHI
- Diet advice
- Prevention
- Liase with orthodontist if concerns
- Make appliance safe
What does the bracket prescription determine?
- The tip, torque and in/out control
