CVC Prep

Question 1

The final shape to a restoration (form of the tooth produced by instrumentation)

Answer 1

Preparation

Question 2

Extracoronal preparation involving the entire clinical crown

Answer 2

Complete veneer crown prep

Question 3

A cast-gold extracoronal restoration which fits the clinical crown

Answer 3

complete veneer crown (CVC)

Question 4

The imaginary line along which a casting is moved when it is separated from its single crowns.
should coincide with the tooth’s long axis

Answer 4

Path of Withdrawal (POW)

Question 5

Part of the crown prep prepared in the long axis of the tooth
can be designated as buccal, lingual, mesial, or distal

Answer 5

axial wall

Question 6

The angle or taper formed by diametrically opposed axial walls

Answer 6

convergence angle

Question 7

The cervical junction of the prepared axial wall and unprepared portion of the structure
Extends around the cervical portion of the tooth prep.

Answer 7

Chamfer

Question 8

Lines formed by the junction of any two tooth surfaces.

Should be rounded in complete crown preps

Answer 8

line angles

Question 9

Junction between any two axial walls

Answer 9

Axial wall line angle

Question 10

Junction between the occlusal surface and an axial wall

Answer 10

occlusoaxial line angle

Question 11

Junction of the prepared to unprepared tooth structure (external line angle)

Answer 11

Cavo-surface line angle

Question 12

Grooved placed on the surface of the tooth to provide a reference to determine when sufficient tooth structure has been reduced.

Answer 12

depth orientation grooves

Question 13

A wide bevel placed on the fuctional cusps.
The thickness of the tooth structure removed when preparing this bevel ensures that correct contours of the final restoration can be re-established while providing correct convergence and adequate thickness of restorative materials.

Answer 13

Functional cusp bevel

Question 14

A crown prep is ___ if a wax pattern cannot be withdrawn from its die without distortion

Answer 14

undercut

Question 15

What causes undercuts?

Answer 15

• a depression in an axial wall (by caries)
• diametrically opposed axial walls that do not converge occlusally caused by improper angulation of the cutting instrument

Question 16

How do you correct an undercut caused by a carious lesion?

Answer 16

a base/build up material

Question 17

How do you correct an undercut caused by improper bur angulation?

Answer 17

requires further tooth reduction

Question 18

Characteristics of the tooth preparation which tends to resist the removal of the restoration along its POW.

Answer 18

Retention form

Question 19

Characteristics of a tooth preparation which tend to prevent dislodgement of a seated restoration by forces directed in an apical or oblique direction.
Prevents dislodgement of the restoration by occlusal forces

Answer 19

Resistance form

Question 20

Name 4 advantages of complete veneer crowns

Answer 20

high strength
longevity
high resistance to displacement
ability to modify axial contours and occlusion

Question 21

Name 4 disadvantages of complete veneer crowns.

Answer 21

Display of metal
removal of tooth substance
vitality testing (pulp testing)
Margin close to gingival tissue

Question 22

What criteria does a patient need to be a candidate for a CVC?

Answer 22

• extensive destruction by caries or trauma
• endodontically treated teeth
• large existing restorations
• maximum retention needed
• recontouring of axial surfaces
• correction of malinclination
• correction of occlusal discrepancies
• have a need to provide contours suitable for removable partial denture

Question 23

What are contraindications of CVCs?

Answer 23

• When a tooth can be adequately restored with a more conservative restoration
• esthetics

Question 24

What could be examples excess reduction of a CVC prep?

Answer 24

• tooth is prepared with excessive convergence angle
• prep does not follow the anatomical features of the tooth
• POW diverges from the long axis of the tooth
• excessively wide margin
• excessive gingival extension of the prep

Question 25

What is the ideal convergence angle of a CVC prep?

Answer 25

between 2 and 10 degrees

Question 26

What is the ideal width of the prep margin?

Answer 26

0.5 mm

Question 27

How far gingivally should a CVC prep go?

Answer 27

no further than retention form and existing restoration or defects dictate

Question 28

When might inadequate marginal integrity occur?

Answer 28

• chamfer is too narrow to provide sufficient bulk of restorative material without over contouring
• cavo-surface line angle cannot easily be determined during lab procedures
• chamfer is rough or uneven
• preparation is undercut causing distortion of the wax pattern

Question 29

What will happen if you have inadequate retention and/or resistance form?

Answer 29

displacement of the restoration

Question 30

What are some causes of inadequate retention/resistance form?

Answer 30

• excessive convergence angle (greater than 10 degrees)
• inadequate height and surface area of the axial walls
• insufficient surface area to resist tipping of the restoration

Question 31

What are the recommended dimensions for CVC prep?

Answer 31

Functional cusp - 1.5 mm taken away
Central groove - 1 mm taken away
Non-functional cusp - 1mm taken away
Chamfer width - 0.5 mm

Question 32

In order, what is the sequence of steps taken to prep a CVC?

Answer 32

1. occlusal guiding grooves
2. occlusal reduction
3. axial guiding grooves
4. axial reduction
   5 finishing and evaluation