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Orthodontics > Fixed Appliances > Flashcards

Fixed Appliances Flashcards

1
Q

Andrew’s 6 key?

A
  • Molar relationship
  • correct crown angulation
  • correct crown inclination
  • curve of spee (flat occlusal plane)
  • no rotation
  • no spaces
    7- size and shape of tooth.
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2
Q

How are these 6 key of occlusion achieved?

A

Precise tooth positioning in 3 dimensions

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3
Q

How each tooth has its own Individual position within arch. How can you spot difference?

A
  • How labially teeth are placed
  • thickness of tooth (labio / lingual)
  • angulation of teeth (upright or tipped)
  • inclination of teeth (retroclined/ Proclined )
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4
Q

Standard edgewise fixed appliances

A
  • 1 type of bracket for all teeth.
  • Archwire was customised (bent) by orthodontist to incorporate the 3 orders of movement in each tooth.
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5
Q

Preadjusted edgewise fixed appliances (SWA)

A
  • individual bracket per tooth with specific 3 orders of movement build in. Called Prescription of bracket.
  • 1 archwire , not customised , appliance called STRAIGHT WIRE APPLIANCE
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6
Q

3 orders of movements

A

1st order - in/out
2nd order- crown tip
3rd order- crown torque

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7
Q

MBT bracket 2nd order movement -Tipping

A

Upper - 1 2 3 4 5 6 7
4 8 8 0 0 5 5

Lower- 0 0 3 2 2 2 2

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8
Q

MBT bracket prescription: 3 order movement t

A

Torque / inclination.
Upper - 1 2 3 4 5 6 7
17,10, -7,-7,-7,-14,-14

Lower- -6,-6,-6,-12,-17,-20,-10

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9
Q

How are the 3 orders of movement built into the bracket?

A

Archwires

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10
Q

Describe a bracket and slot size ?
MBT ( preadjusted fixed appliance bracket)

A

1- four tie wings
2- Archwire slot 0.022x0.028 most common in uk
3- Archwire slot 0.018x0.025
4- base
5- identification marking
6- curved base helps bracket location, seating and stress distribution

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11
Q

How do you know where to place a bracket to get the best end result?

A
  • you need a reference point/ position
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12
Q

Correct bracket positioning on the tooth surface?

A

Central slot of bracket must be correctly positioned with respect to:

1- Incisal edge /cusp tip
2- mesio- distal position
3- long axis

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13
Q

What is LACC and LA point?

A
  • LACC - long axis of clinical crown
    -LA- midpoint of crown on LACC
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14
Q

What safety issues do we need to consider when bonding?

A
  • Etch should not touch soft tissue as it’s phosphoric acid
  • Inhalation and ingestion of bracket or wire piece.
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15
Q

Lower incisor brackets placement

A

-similar height and correct

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16
Q

What can you us to remove flesh of composite?

A

Hockey stick
Probe
Mitchell trimmer

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17
Q

What position of bracket should be for palatally placed upper lateral incisors ?

A

Inverted bracket
So labial root torque is introduced rather than palatal root torque.

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18
Q

Swapping lower canines (class 3cases) ? Why

A

Reverse tip NOT torque

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19
Q

Which guage you can use to decide elastic size?

A

Orthodontic force guage

20
Q

Moving canine into lateral incisor position? How? Hypodontia case

A
  • inverting upper canine
  • bonding premolar slightly more distal to bring buccal eminence so premolar can have canine like appearance
21
Q

Bracket materials?

A

Metal - stainless steel, cobalt chronium, titanium, gold
Ceramic- mono crystalline aluminium oxide ( clear ) polycrystalline aluminium oxide (opaque)
Plastic - polycarbonate, thermoplastic polyurethane.

22
Q

Metal bracket

A

-Most commonly used
- composition varied (AISI- American iron & steel institute)

23
Q

Metal bracket method of manufacture?

A

1- Milled (e.g Dynalock)
2- Cast (e.g. A co . St)
3- injection moulded .

24
Q

Method of retention for bracket

A
  • Primarily mechanical
  • methods use to increase surface area for bonding e.g mesh, laser etched, sandblasted , silicon coated
  • curved base helps bracket location, seating, and distribute stress point
25
Q

Desirable features of metal brackets?

A
  • good bond
  • low friction
  • non toxic
  • corrosion resistance
  • poor biohost i.g plaque resistance
  • cheap and easily available
  • resist deformation by patient
  • easy to debond
  • radiopaque
  • long shelf life
26
Q

Ceramic brackets properties

A
  • brittle
  • high compressive strength
  • low tensile strength
  • hard
  • resistance to stain
  • chemically inert
27
Q

Ceramic bracket pros / cons

A

Pros :
-asthetic ,
-abrasion resistance,
-chemically inert
-poor biohost,
-good biocompatibility
-useful for nickel allergy patient.

Cons :
Expensive
Abrasive to tooth
Friction with archwire
Brittle
Difficult Debond. Carful with RCT / heavily filled tooth

28
Q

Plastic Brackets ?

A
  • Good for asthetic
  • wear off easily
  • staining
  • 0 torque transfer
29
Q

Self ligating brackets how many kinds?

A
  • Active : In- ovation R and speed
  • passive - Damon and smart clip
30
Q

Self ligating bracket Adv/ dis advantage

A

Advantages:
-Full archwire engagement
- less chair side assistance requires
- less chair time required
- reduced number of appointments
- improved infection control.

Disadvantages:
- takes practice
- clips fracture or opening between appt
- No partial ligation
- wire sliding round
- cost
- no evidence of faster alignmentment or space closure

31
Q

Cleats

A
  • Cross elastics
  • place powerchain or power thread
32
Q

Eyelets

A
  • uses auxiliaries to pull palatal canine into alingment e.g powerchain or thread
  • run archwire through
33
Q

Buttons

A
  • cross elastics to correct crossbite
  • to add chain to derotate tooth
34
Q

BITE TURBO

A
  • reduce overbite
  • made of steel or composite
35
Q

Begg bracket

A
  • to pull palatal canine
  • run archwire through and use Begg pin to hold wire. Rarely use
36
Q

Ideal properties of orthodontic adhesive

A
  • easy to use
  • single component
  • No enamel pre tx required
  • adhesive to wet
  • adhesive to metal/ palctic/ ceramic
  • sufficient bond strength to enamel and bracket
  • cheap
  • non toxic
  • poor biohost
  • sustained fluoride
  • cohesive strength less than enamel
  • long shelf life
  • good aesthetics
  • BOND SHOULD LAST 2 years
37
Q

Explain Bonding process?

A
  • Pumice with oil free brush
  • isolate teeth ( cheek tetractor) and suction
  • Dry suction and air dry
  • place etch 37% o-phosporic acid 15-30 seconds
  • rinse water spray
  • Dry - oil free compressed air until frosty white appearance.
  • infilled resin or primer
  • place bracket
  • remover excess adhesive
  • light cure 440-480 nm for 10s / interspace
  • remove lip retractor
38
Q

How can you remove pellicle and plaque?

A
  • cups vs bristle brush
  • prophypate vs Pumice
39
Q

Pumicing

A

Study shows it has no effect on bond failure

40
Q

Why etch ?

A

To increase surface area for bonding by increasing surface area.

41
Q

Etch concentration

A

30% - 50% o- phosphoric acid

42
Q

Bond Application what does it do!?

A
  • unfilled resin or primer
  • protects etched enamel

COMMON CAUSE OF DERMATOSES IN DENTAL PERSONNEL

43
Q

Example of light cure composite

A
  • Transbond
  • adhesive precoat
44
Q

Potential failing with fixed appliances?

A
  • Inaccurate bracket position.
  • Slop
  • variation in tooth structure.
  • Variation in skeletal pattern. (D.A compensation).
  • Force diminution- Less with NITI
45
Q

What are the factors that make the brackets different for each tooth

A

3 order movements
- 1st order- In / out
- 2nd order- Tipping
-3rd order- Torque

Orthodontics (53 decks)

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