CLASS 3 AND CLASS 4 Flashcards

1
Q

Difference of class 3 and class 4?

A

Class 3 does NOT involve the incisal angle

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2
Q

What is the labial and gingival length in Class 4 cavity preparations?

A

6 mm

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3
Q

What it the axial depth of class 3?

A

1 mm

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4
Q

When you have a large cavity that is not confined to the enamel, what kind of class 4 should be done?

A

Beveled conventional tooth preparation

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5
Q

General tooth preparation involves?

A

Obtaining access to defect
Removing faulty structures
Creating the convenience form for the restoration

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6
Q

How does the restoration stick in class 3?

A

Chemical bonding

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7
Q

Additional preparation is required for class 3, T or F?

A

False but it can be done

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8
Q

When is addition retention form needed? and what do you do?

A

Large cavity

Increase the surface area with a wider enamel bevel

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9
Q

Indications for labial approach in class 3?

A

Carious lesion is located facially
Teeth are irregularly aligned
Extensive carious lesion extending into the facial surface
Faulty restoration that was placed from the facial approach that needs to be replaced

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10
Q

What bur is used in Lingual approach?

A

Round bur that is 0.7 or 0.8 mm

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11
Q

Where is the point of entry in lingual approach/

A

At the level of the lesion making sure to not hit the adjacent tooth

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12
Q

What kind of stroke is used to access the lesion in lingual approach?

A

Brush stroke, light pressure and intermittent cutting

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13
Q

What dictates the outline form of a class 3 in a normal tooth?

A

Carious lesion

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14
Q

Ideal axial wall depth in a Class 3

A
  1. 75 to 1.25 mm

0. 2 mm into the dentin

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15
Q

Shape of the normal external tooth contour that should be followed in a class 3 ?

A

Convex

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16
Q

This aids in the retention form of class 3

A

Boxlike design

Opposing wall parallelism
Slight undercuts
Rough prepared walls

17
Q

When is beveling done in a class 3 cavity prep?

A

For replacing an existing defective restoration

For Large carious lesions

18
Q

Where is the bevel placed, why? and when is beveling done, why?

A

Bevel is placed labially because mastication forces are too heavy on the lingual.

Beveling is done when the tooth or the CSM is not in contact with the opposing tooth during occlusion

19
Q

What is the appearance of a class 3 cavity prep? Outline form, Axial Depth, Incisal and gingival wall and Labial depth?

A

Outline form - Rectangular with rounded sides
Axial depth - 1 mm
Incisal and gingival wall - 3 mm
Labial depth - 1.5 mm

20
Q

Where is the class 3 cavity prep placed on a tooth?

A

Middle 3rd

21
Q

What are the types of class 4 tooth preparations?

A

Conventional tooth preparation
Beveled conventional tooth preparation
Modified class 4 preparation

22
Q

in this type of tooth preparation, beveling is not needed. why?

A

Conventional tooth preparation bc of the 90 degree CSM

23
Q

This type of tooth preparation is used for Large cavities?

A

Beveled conventional tooth preparation

24
Q

Retention in beveled conventional tooth preparation is obtained by?

A

Groove or other shaped undercuts
Dovetail extension
Threaded pins

25
Q

How big are dovetails and what tooth surface are they usually placed on ?

A

0.5 to 1 mm on the lingual

26
Q

This is done to resist biting forces in beveled conventional tooth preparation

A

Walls are prepared Parallel and Perpendicular to the long axis of the tooth

27
Q

Initial axial wall depth

A

0.2 to 0.5 mm

28
Q

Can you use ZOE as a liner or base for composite? Why?

A

no bc it will affect the polymerization of composite

29
Q

Steps in beveling?

A

45 degrees to the external tooth surface

Flame shaped bur is used

30
Q

What is the width of the bevel?

A

0.25 to 2 mm

this will depend on how big the class 4 is

31
Q

This is done when the class 4 is confined in the enamel

A

Modified class 4 tooth preparation

32
Q

What bur is used for class 4 tooth preparation

A

Flame shaped

33
Q

What is the height, axial width and the labial depth at the tip and at the gingival of a class 4 tooth preparation?

A

Height - 6 mm
Axial width 1 mm
Labial depth at the tip - 0.5 mm
Labial depth at the gingival - 1.5 mm

34
Q

Cavity with access is also known as

A

Direct proximal preparation

35
Q

What is the outline form of direct proximal preparation?

A

Triangular

36
Q

Where are undercuts in direct proximal preparations?

A

Along the DENTIN of gingival and incisal walls