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iodc > fixed appliances > Flashcards

fixed appliances Flashcards

1
Q

What are the different types of tooth movement?

A

Tipping
Bodily movement
Rotation
Torque
Vertical movements (extrusion/intrusion)

Removable can do tipping too but none of the other movements

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2
Q

What are problems/risks of fixed appliances?

A

Demineralisation/caries
Root resorption
Soft tissue lacerations
Perio problems (gingivitis/recession)
Pulp devitalisation
Relapse
Unwanted tooth movements

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3
Q

What are the components?

A

Brackets
Molar tubes/bands
Archwires
Auxillaries

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4
Q

What are archwire materials?

A

Nickel Titanium (super elastic/heat activated)
Stainless steel

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5
Q

What are brackets?

A

Pre adjusted edgewise
Stainless steel or ceramic or even plastic
Has tie wings and a slot (for metal tie/elastic module)
Most common slot size- 0.022’x0.028’
Bracket base- foil mesh for retention with composite
Slot in middle for probe to seat
Specific brackets for every tooth (prescription of tip and torque)
5-5

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6
Q

What is the wire progression?

A

1. Round wires- initial tooth alignment (flexible NiTi)
2. Increase in rigidity and thickness
3. Rectangular wires- (1925) final alignment and space closure (aka working archwire) this is the aim

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7
Q

What is the maximum dimension of wire?

A

0.019’x0.025’

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8
Q

What are aesthetic brackets?

A

Ceramic- fracture in use and debonding/abrasion of other teeth/increased friction/cost

Lingual (SS) - difficult technique/cost/trauma to tongue

Plastic- fracture/distort/discolour

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9
Q

Why is tungsten carbide good for debonding?

A

Removes composite but not enamel

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10
Q

How should ceramic brackets be used?

A

Upper arch only to avoid abrasion of other teeth
Lower arch only if no OB

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11
Q

What are molar bands?

A

Lower- single tube for archwire, hook for auxiliaries

Upper- additional tube for head gear (round, not used for archwire), hook for auxiliaries

Need to place ortho separators for a week

Different sizes, should be close fitting, can be adapted

Place w GIC, pt can bite down on a instrument to help seat

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12
Q

What are the benefits of ortho separation for molar bands?

A

More comfort for patient
Easier for operator
More accurate band selection

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13
Q

What are molar tubes?

A

Can bond tube to tooth- has hook and tube- similar to bracket
Don’t need to place separators
Difficult isolation from moisture- more likely to debond
Problem w wire if debonds
Can’t use headgear

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14
Q

What is the function of archwires?

A

Active- move teeth with wire for alignment- light forces, flexible, NiTi

Passive- teeth move along wire for bodily movement w help of accessory components- rigid, SS

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15
Q

What is the cross section of archwires?

A

Round wires- 0.012’ to 0.018’ (usually goes up in 2s so 012, 014 etc)

Rectangular wires- 0.019’x0.025’

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16
Q

How is the arch wire attached?

A

Elastic modules- O shape or figure of 8 for reinforcement

If needs even more reinforcement can use wire ligatures (quick ties)

Self ligating brackets (reduces friction) slot wire in and shut a door- uncomfortable, takes longer, narrower arch and flat profile

17
Q

What are auxiliaries?

A

ELASTICS
bands O
power chain ooo
zing string (elastic thread) —
e-links o—o
traction ligatures oxx

SPRINGS
push coil/coil spring —xxx—
closing coil/retraction spring oxxo

18
Q

What does a fixed appliance kit have?

A

Weingarts- grips archwires

Tucker- tuck end of quick ties

Adam’s pliers- make bends in archwires or adjust clasp on removable appliances

Light wire plier cutter- cut light wires/elastics

Distal end cutters- right angle, cut end of archwires

Crown shears- cut ends of quick ties

19
Q

Why is Invisalign not as effective?

A

Doesn’t allow the same range of movements

20
Q

Where did the Andrews 6 keys to normal occlusion (1972) come from?

A

120 sets of models (from local dentists/orthodontists/unis)

Wanted straight teeth, pleasing appearance, correct bite, no need for ortho

Compared w models that had ortho w v good results

21
Q

What are the 6 keys?

A

1. Molar relationship (class I)
2. Crown angulation (tip)- root tipped distally by 5 degrees for molars and incisors and 11 for canines
3. Crown inclination (torque)
4. No rotations- molars need more space compared to incisors
5. Tight contacts- no crowding/spacing
6. Flat curve of Spee- flat occlusal plane

22
Q

What does the straight wire appliance have built in?

A

Tip (eg. Andrews values- U3 is 11 degrees so angle of slot in bracket is rotated)
Torque (slot in bracket is rotated up or down)
In-out (different bracket base thicknesses, distal offset of upper molars)

For each individual tooth

23
Q

What are the main stages of tx?

A

Levelling and alignment (vertical/buccolingual/mesiodistal movements and correct rotations)
Space closure (OJ reduction, centre line correction)
Additional stages (OB/CB correction, finishing and detailing)

24
Q

What is the choice of initial archwire?

A

NiTi round wires

Or even beta titanium (TMA) or super elastic or SS (multistrand)

25
Q

What is the problem of tip in canine brackets?

A

Crown moves forward
Incisors extruded
Bite deepens

So we use CANINE LACEBACKS (ligature wire under archwire)

Prevents canine moving mesially
Posterior teeth can move forward

26
Q

What are space closure methods?

A

NiTi springs
Power chain
Traction ligatures

27
Q

What are some additional stages?

A

Make finishing bends in wire as prescription brackets may only go 95% of the way
Box elastics can improve occlusion

28
Q

What are types of retainers?

A

Removable
-acrylic (hawley)
-vacuum formed (Essix)

Fixed
-bonded

29
Q

What are hawley retainers?

A

Acrylic from palate to palatal surface of incisors (locks posterior teeth)
Cribs on 6s for retention
Adam’s clasps
Labial bows

30
Q

What is the retention regime?

A

12hrs/day for first year
Alternate nights for the second year
Gradual withdrawal
Minimum 1x a week indefinitely

31
Q

What teeth are prone to relapse?

A

Perio involved teeth due to lack of bone support
Midline diastemas
Severe rotations- pericisions (supracrestal fibres want to pull them back)
Teeth out of zone of stability w soft tissues (eg. proclined lower incisors/OJ reduction w incompetent lips)

32
Q

What is pericision?

A

Circumferential supracrestal fibrotomy

iodc (63 decks)

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