Removable Appliances

Question 1

Parts of a Lab card for a URA in orthodontics

Answer 1

1. AIM
   - what trying to do with THIS specific appliance (not overall tx goal)
2. ARAB

Active components
- what is moving teeth (.5mm HSSW)

Retentive factor
- resistance to displacement forces (5)
- gravity, mastication, talking, tongue, active components

Anchorage
- resistance to unwanted tooth movement
- newtons 3rd law (every action has an equal and opposite reaction)
- must only target movement of 2 teeth max so opposite reaction shared among many other teeth

Base plate
- holds together, retention (suction), helps anchorage
- Self cure PMMA

Question 2

What type of PMMA is used for URAs and why

Answer 2

Self cure
- as takes 15 mins to make

Heat cure
- however has a better work time, strength, less shrinkage and residual monomer
- used if allergic to acrylic monomer

Question 3

Active components for URAs (4)

Answer 3

Palatal finger springs + GUARD
- i.e. distalises 3

Z spring
- buccal movement
- slight rotations (engaging one spring more than the other)

Buccal canine retractor + 0.5mm ID tubing
- INTERNAL DIAMETER tubing
- palatal and distal movement
- Buccally placed

Robert’s retractor + ID tubing
- palatalise anterior teeth
- trim acrylic behind anterior when activate more
- Functional appliance for overbite and over jet

Question 4

Retentive components for URA

Answer 4

All 0.7mm HSSW

Adams clasp
- molars or pre molars

southend clasp
- central incisors

labial bow
- spans all incisors

Question 5

what are the different parts of an adams clasp

Answer 5

1. tag
2. leg
3. fly over
4. arrow head
5. bridge

Question 6

What are additions to a URA baseplate that can be made

what are these for

Answer 6

Anterior flat bite plane
- ONLY for OverBITE

Posterior flat bite plane
- i.e. for crossbite

Question 7

What tools are used in URA component creation

Answer 7

adam 64 pliers

adam 65 wire coilers

wire cutters

Question 8

what is the purpose of an URA with an anterior bite plane and how would this be prescribed

Answer 8

• to reduce overBITE
• biteplane = overjet + 3mm (so dont retrocline lowers)
• disoccludes posteriors, causing further eruption of both upper and lower posteriors
• causes ANTERIOR OPEN BITE
• wear for longer than when contacting as new soft bone will resorb

Question 9

When is a posterior flat bite plane used on an URA

Answer 9

• anterior cross bites
• posterior cross bites (with mid palatal screw)