Removable appliances in orthodontics Flashcards
Advantages of removable appliances?
Removable
Disadvantages of removable appliances?
Removable - not in mouth, lost/damaged Can only tip teeth Affects speech Poorly tolerated in lower arch Intermaxillary traction not possible Inefficient for multiple tooth movements
What does fully controlled movement require?
Attachment to tooth
Components (ARAB)/design of removable appliances?
Active components - how to move teeth
Retention - Stop if falling out
Anchorage - stop the wrong teeth moving
Baseplate and biteplanes
What active component is preferred to move teeth with removable appliances?
Most preferred = Springs - palatal, buccal
Screws
Least = elastics
What does the force of a spring depend on?
Thickness of wire - Force alpha diameter (squared 4)
Length of wire - Force alpha 1/length (squared 3)
Amount of deflection
What diameter wire is used for active components?
0.5-0.6mm diameter wire
How to increase the wire length?
Coil near acrylic
Palatal finger spring features?
0.5 or 0.6mm wire Coil near acrylic increases length Coil on side away from direction of movement Can use on any teeth Not good on buccally placed teeth
How to adjust screws?
Quarter turn = 0.2mm
1 turn per week = just less than 1mm per month
2 turn per week = just less than 2mm per month
Indications for screws?
Moving blocks of teeth
Can move tooth and use for retention
Features of ortho elastics?
Poor control
Rarely used
How is posterior retention achieved with removable appliances?
Adams cribs - MB and DB undercuts of 0.25mm
How is anterior retention achieved with removable appliances?
C-clasp
Southend clasp
What is anchorage?
Control of unwanted tooth movement
How to not lose anchorage?
Light forces
Only move one tooth per side
Large anchor unit - more teeth included in appliance design
Headgear?
Problems with headgear?
Co-operation
Safety
How long should pts wear headgear a day?
12 hours per day (pt’s actually only wearing them 6.5hrs a day)
Why is headgear safety important?
Catapulting accident
Night-time dismantling
Problems of eye injury from headgear?
High risk of infection
Excellent culture medium
Difficult to control with antibiotics
Sympathetic ophthalmitis
What is a baseplate’s functions?
Connect components
Carries passive wirework
Additional anchorage
Carries biteplanes
Types of biteplanes and their uses?
Flat anterior bite plane - reduces overbite
Inclined bite plane - post functional appliances - retains functional appliance treatment, proclines lower incisors (negative)
Posterior biteplane - free the occlusion
Cases to treat with removable appliances?
Disimpaction of 1st molars Class III - anterior crossbite Posterior crossbite in mixed dentition or expansion prior to functional appliances Space maintenance Overbite correction
How to adjust an adams crib?
Gently roll arrowhead in or out with pliers
How to adjust a Z spring?
Pull forwards and upwards - away from baseplate
How to fit an upper removable appliance?
Check lab ticket Explain how the appliance works Try in Adjust retentive components if required Activate Adjust bulky biteplates if appropriate Demonstrate then check pt can fit and remove Instructions when to wear, how to clean Document everything done
How to do a visit by visit assessment?
Talk to pt and parent Assess for signs of wear Assess progress, measure changes Assess OH Assess retention Check if active component is active Reassess anchorage Document findings and plan
