URA Flashcards
List advantages of removable appliances (URA).
(7)
- can be removed for TB (oral hygiene)
- palatal coverage increases anchorage
- easy to adust
- less risk of iatrogenic damage e.g. root resorption, compared to fixed appliances
- arylic can be thickened to form a FAMP or buccal capping
- useful as a passive retainer or space maintainer
- can be used to transmit forced to blocks of teeth
List disadvantages of removable appliances (URA).
(7)
- appliance can be left out
- only tilting movements possible
- good technician required
- affects speech
- intermaxillary traction more difficult
- lower removable appliances are difficult to tolerate
- inefficient for multiple individual tooth movements
Describe the instructions you would provide a patient on URA delivery.
(10)
- The appliance will feel big and bulky. Reassure that this is normal, and they will get used to it.
- Initial excessive salivation. This will pass in 24h.
- May impinge speech for a short period of time. Practice reading a book aloud at home and this will subside.
- May cause initial discomfort/ache. This is normal and indicates that the appliance is working.
- To be worn 24/7 including meal times and sleep.
- Remove after every meal and clean with a soft brush (no need for TP).
- Remove and store in a protective container when participatin in contact or active sports.
- Avoid hard or sticky foods that may damage the appliance and be cautious with hot food and drinks
- Missing appointments and non-compliance will significantly lengthen the treatmet time.
- Provide emergency contact details in case any problems arise.
How much of tooth movement is the aim per month?
1mm movement per month
What is anchorage?
Resistance to unwanted tooth movement
What is the function of the baseplate in a URA?
- connects all components together (connector)
- retention (cohesion, adhesion)
- anchorage (prevents anchorage loss)
What is the function of the active component in a URA?
applies force
What is the function of the retentive components in a URA?
resists displacement to retentive forces
What are the 5 forces in the oral cavity that can displace a URA?
- occlusal forces (mastication)
- tongue (to roof of mouth)
- vertical forces (gravity)
- speech (vibrations to palate)
- active components
Describe the lab instructions you would provide to correct anterior crowding + 6mm OJ.
Aim: Please construct a URA to retract 13+23
A: 13+23 palatal finger spring + guards; 0.5mm HSSW
R: 16+26 Adams clasp; 0.7mm HSSW
11+21 Southend clasp; 0.7mm HSSW
A: moving to two teeth ✅
B: self-cure PMMA
Describe the lab instructions you would provide to correct overbite.
Aim: Please construct a URA to retract 13+23 and reduce overbite (OB)
A: 13+23 palatal finger spring + guards; 0.5mm HSSW
R: 16+26 Adams clasp; 0.7mm HSSW
11+21 Southend clasp; 0.7mm HSSW
A: moving two teeth ✅
B: self-cure PMMA + flat anterior bite plane (FABP); OJ + 3mm
Describe the lab instructions you would provide to correct bucally placed canines.
Aim: Please construct a URA to retract bucally placed canines, first premolars extracted, 6mm OJ and reduce OB
A: 13+23 buccal canine retractors; 0.5mm HSSW + 0.5mm ID tubing
R: 16+26 adams clasp; 0.7mm HHSSW
11+21 southend clasp; 0.7mm HSSW
A: moving two teeth ✅
B: self-cure PMMS + FABP; OJ + 3mm
Describe the lab instructions you would provide to correct anterior crossbite.
Aim: Please construct a URA to retract anterior cross bite on 12
A: 12 Z-spring; 0.5mm HSSW
R: 14+24+16+26 adams clasp; 0.7mm HSSW
A: moving one tooth ✅
B: self-cure PMMA; posterior bite plane (PBP)
Describe the lab instructions you would provide to correct increased overjet.
Aim: Please construct a URA to reduce overet (OJ) 22, 21, 11 and 12 + reduce OB
A: 22+21+11+12 roberts retractor; 0.5mm HSSW + 0.5mm ID tubing
13+23 mesial stops; 0.7mm (flattened) HSSW
R: 16+26 adams clasp; 0.7mm HSSW
A: moving four teeth, acceptable anchorage as centrals and laterals have short roots
B: self-cure PMMA; FABP; OJ + 3mm
Describe the lab instructions you would provide to expand the maxillary arch.
Aim: Please construct a URA to expand the upper arch
A: midline palatal screw
R: 14+24+16+26 adams clasp; 0.7mm HSSW
A: reciprocal anchorage ❌
B: self-cure PMMA
Pt. instructions:
Turn the screw 1-2x a week to achieve 0.2-0.25mm movemennt a week.
In posterior crossbites, a PBP can be used to temporarily create a posterior open bite (lower teeth may be blocking movement of upper teeth)
