Complete Cast Crown Preparations Lecture 2

A complete crown has both _______ and ______ than the partial coverage restorations.

greater retention

resistance

T/F: Complete crowns are more easily deformed than partial coverage restorations.

False. complete crowns are less easily deformed.

Complete crowns allow for complete coverage, which allows the operator to modify the axial contour of the tooth to some degree. Why might this be beneficial?

This allows us to change the contour or malposed teeth, or possible re-contouring to close the spacing between teeth.

What limits the amount of re-contouring we can perform?

periodontal considerations

Complete crowns allow for the change of contour of a tooth for oral hygiene. What are two examples? In what cases might this be beneficial?

fluting or barreling

allows for easier access to furcation for cleaning

T/F: partial coverage restorations do not allow us to modify the occlusion.

True. we are restoring the tooth to form and function

T/F: complete crowns allow us to modify the occlusion.

True.

When is it critical to be able to modify occlusion with complete crowns?

when teeth are supraerupted or when changing vertical dimension of occlusion

What are four advantages of cast crowns vs other crowns?

longevity of cast crowns (specifically gold) is superior to that of all other fixed restorations.

complete cast crown strength is superior to that of other restorations.

see reduced wear of opposing teeth (as opposed to porcelain)

high material strength allows for most conservative preparations

What are some disadvantages of cast crowns?

esthetics (made of gold)

cost (very expensive)

Cast crowns are normally limited to maxillary ______ and mandibular ________ and ______, but can be altered by patient’s esthetic demands and ________.

molars

molars

premolars

smile line

What are some indications for cast crowns?

They are indicated on heavily restored teeth that have extensive coronal destruction by caries or trauma

The restoration will be in an area of high occlusal load that is not easily visualized

Indicated, along with PFMs, to support partial dentures

Fabricating survey crowns

Why are cast crowns the ideal treatment for endodontically treated posterior teeth?

The strength of the cast crown compensates for the loss of tooth structure from endodontic access and former carious lesions

What are two contraindications for a cast crown?

If you can achieve the same treatment goals with a more conservative restoration such as an onlay

depending on the patient, esthetic concerns often limit the placement to the molars and mandibular premolars

In an ideal prep, there would be an increased occlusal reduction on the __________.

Functional cusp

What is the taper needed for a cast crown?

6-degree taper

For a cast crown prep, a supragingival chamfer margin needs ____ mm thickness of material.

0.5 mm

In a cast crown prep, there is a bevel on the __________.

functional/working cusp

The functional cusp bevel angle is approximately _________ to the long axis of the tooth.

45-degrees

What term is defined as the amount of space between the prepared tooth and its opposing tooth?

clearance

What term is defined as the amount of tooth structure removed to establish the desired clearance?

reduction

How can we check the reduction?

by using a putty matrix

How can we check the clearance?

digital scanner measures clearance

The minimum recommended clearance is ______ on non-functional cusps and is _______ on functional cusps.

1mm

1.5mm

T/F: To achieve the minimum clearance, we must achieve 1-1.5mm of reduction.

False

What is the order for the prep walkthrough in the textbook?

placement of guide grooves with carbide bur

occlusal reduction with round end taper diamond

placement of axial guide grooves with taper diamond

axial reduction with round end tapered diamond

finishing

T/F: Zirconia and porcelain are equal in strength.

False. zirconia is much stronger than porcelain.

Zirconia is a dental _____ just like porcelain.

ceramic

Due to increased strength, a zirconia crown prep design is similar to _____. The difference is additional _____ and ______ reduction are recommended.

cast metal crown prep

axial

occlusal

Which crown type offers an esthetic alternative to cast metal?

zirconia