CLASS 3 AND CLASS 4

Question 1

Difference of class 3 and class 4?

Answer 1

Class 3 does NOT involve the incisal angle

Question 2

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

Answer 2

6 mm

Question 3

What it the axial depth of class 3?

Answer 3

1 mm

Question 4

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

Answer 4

Beveled conventional tooth preparation

Question 5

General tooth preparation involves?

Answer 5

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

Question 6

How does the restoration stick in class 3?

Answer 6

Chemical bonding

Question 7

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

Answer 7

False but it can be done

Question 8

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

Answer 8

Large cavity

Increase the surface area with a wider enamel bevel

Question 9

Indications for labial approach in class 3?

Answer 9

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

Question 10

What bur is used in Lingual approach?

Answer 10

Round bur that is 0.7 or 0.8 mm

Question 11

Where is the point of entry in lingual approach/

Answer 11

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

Question 12

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

Answer 12

Brush stroke, light pressure and intermittent cutting

Question 13

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

Answer 13

Carious lesion

Question 14

Ideal axial wall depth in a Class 3

Answer 14

0. 75 to 1.25 mm

0. 2 mm into the dentin

Question 15

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

Answer 15

Convex

Question 16

This aids in the retention form of class 3

Answer 16

Boxlike design

Opposing wall parallelism
Slight undercuts
Rough prepared walls

Question 17

When is beveling done in a class 3 cavity prep?

Answer 17

For replacing an existing defective restoration

For Large carious lesions

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

Middle 3rd

Question 21

What are the types of class 4 tooth preparations?

Answer 21

Conventional tooth preparation
Beveled conventional tooth preparation
Modified class 4 preparation

Question 22

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

Answer 22

Conventional tooth preparation bc of the 90 degree CSM

Question 23

This type of tooth preparation is used for Large cavities?

Answer 23

Beveled conventional tooth preparation

Question 24

Retention in beveled conventional tooth preparation is obtained by?

Answer 24

Groove or other shaped undercuts
Dovetail extension
Threaded pins

Question 25

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

Answer 25

0.5 to 1 mm on the lingual

Question 26

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

Answer 26

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

Question 27

Initial axial wall depth

Answer 27

0.2 to 0.5 mm

Question 28

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

Answer 28

no bc it will affect the polymerization of composite

Question 29

Steps in beveling?

Answer 29

45 degrees to the external tooth surface

Flame shaped bur is used

Question 30

What is the width of the bevel?

Answer 30

0.25 to 2 mm

this will depend on how big the class 4 is

Question 31

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

Answer 31

Modified class 4 tooth preparation

Question 32

What bur is used for class 4 tooth preparation

Answer 32

Flame shaped

Question 33

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

Answer 33

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

Question 34

Cavity with access is also known as

Answer 34

Direct proximal preparation

Question 35

What is the outline form of direct proximal preparation?

Answer 35

Triangular

Question 36

Where are undercuts in direct proximal preparations?

Answer 36

Along the DENTIN of gingival and incisal walls