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Direct/Cariology > 3. Matrix and Retainer Systems > Flashcards

3. Matrix and Retainer Systems Flashcards

1
Q

What are the purposes of having a matrix with amalgam

A
  1. Confine amalgam so adequate forces can be applied
  2. Reestablish contact
  3. Establish Physiological contour of proximal contact
  4. Prevent extrusions and overhangs
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2
Q

Describe the properties on a prep for an amalgam restoration that make it successful

A
  • box like

- confining walls and floors

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3
Q

A properly placed matrix should have what properties

A
  1. Rigid against existing tooth
  2. proper anatomic contour
  3. Prevent gingival overhang
  4. easily removed
  5. restore correct proximal contact
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4
Q

list the four different parts of the tofflemire retainer

A
  • head
  • slide or vice
  • rotating spindle
  • set screw or locking nut
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5
Q

the head should be held with the slots facing (occlusally/gingivally) when placing the band in but (occlusally/gingivally) when placed on the tooth

A

occlusally….gingivally

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6
Q

When is a matrix needed

A

when a restoration goes from one surface to another

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7
Q

The purpose of the slots in the head are for…

A

positioning the matrix band

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8
Q

The diagonal slot on the slide is meant to hold - mm of the round ends of the matrix beyond the slot

A

1-2

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9
Q

the extent to which the matrix surpasses the diagonal slot of the slide/vice depends on what variable

A

size of the tooth

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10
Q

There should be more band extending out of the slide for a PM or a molar

A

PM

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11
Q

For band installation where is the slide positioned relative to the head

A

next to it

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12
Q

What does the rotating spindle do

A

adjusts the distance between the slide and head and thus adjusts the size of the band

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13
Q

what is the role of the set screw/locking nut

A

locks and unlocks the matrix band in the slide

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14
Q

What are the two types of matrix retainers

A
  • straight

- contra-angled

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15
Q

The names for the two different matrix retainers are based on what processes

A

-the angle between the head

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16
Q

contra-angled are good for what types of restorations

A

ones that are on the lingual surfaces of teeth

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17
Q

What are the three different flat band thicknesses

A
  • 0.001 inch
  • 0.0015 inch
  • 0.002 inch
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18
Q

What is the difference between the thick and thin flat bands

A

thin establish a tighter contact and thicker are more rigid for condensation forces

19
Q

What are the three different types of flat bands and describe them

A
  • # 1= universal band- most commonly used
  • # 2= MOD band has two projections for deep gingival margins
  • # 3= Also has 2 gingival projections but is more narrow than #2
20
Q

The #2 band is better for (molars/PMs) verses #3 which is better for (Molars/PMs)

A

molars….PMs

21
Q

What is the name of the pre contoured bands

A

Getz contour

22
Q

Why must you be careful when removing the pre contoured bands

A

need to make sure you don’t break the marginal ridge

23
Q

When would you want the band to project from the retainer straight

A

when restoring anterior teeth (posterior should be angled left or right)

24
Q

Which quadrants should the band be turned left for? right?

A
  • Left= 1 and 3

- Right= 2 and 4

25
Q

The loop of the matrix should be shaped like a funnel- the wider part should point

A

occlusally

26
Q

Why do you use a wedge with a matrix

A

prevent gingival overhang, makes tight proximal contact to compensate for the thickness of the matrix

27
Q

Which embrasure should you place the wedge in

A

the largest embrasure (lingual for posterior teeth)

28
Q

If the base of the wedge can’t be placed gingival to the prep what will happen

A

a concavity will develop in the matrix

29
Q

What can you do to get rid of the concavity formed when the base of the wedge can’t be placed gingival to the margin of the prep

A
  • surgically reflect the dental papilla

- use a rigid bladed instrument to hold the matrix gingival to the prep

30
Q

How should you burnish the matrix

A

-burnish on a cushioned surface with the back of a spoon excavator or ball burnisher

31
Q

How should a retainer and matrix be removed

A
  • Loose the slide and set screw
  • Pull retainer occlusally
  • Pull distal matrix occlusally and lingually
  • Pull mesial matrix occlusally and facially
32
Q

(T/F) You can reuse a matrix band

A

F- one time only

33
Q

The band should extend _-_mm above the marginal ridge and cavosurface margin and why?

A

1-1.5… need to overpack restoration with amalgam

34
Q

The gingival portion of the band should be _ mm below the gingival

A

0.5 mm

35
Q

How do you tighten the matrix band

A
  • Turn the rotating spindle to decrease the diameter of the matrix band and tighten it
  • Place wedge then loosen the matrix band by turning the knob 1/4th a turn to prevent the matrix from being too tight (prevent an open contact
36
Q

Automatrixing systems are good for what kind of amalgam restorations

A

-complex ones and core build ups

37
Q

What is the major advantage of the automatrixing system

A

has its own built in retainer that is smaller than a tofflinmyer

38
Q

What is the advantage of a denovo matrix system

A

pre welded band with specific sizes and no retainer is needed

39
Q

How is a denovo matrix system removed

A

-bur is used to cut the welds

40
Q

Describe the T band matrixing system

A
  • simple and inexpensive

- built in retainer- smaller than toffelinmire

41
Q

Describe palodent matrixing system

A
  • precontouring and no need for matrix when restoring one proximal surface
  • 2 proximal surface you need 2 small retainers, 2matrices, two wedges
42
Q

Under what cases is reinforcing matrices with modeling compound not needed

A

when the matrix is supported by adjacent teeth

43
Q

How can you prevent the matrix from coming into contact with resin from bonded amalgam

A

coat with wax/crayon

Direct/Cariology (20 decks)

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