Lecture 4 - 02202024

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Questions and Answers

What is a key advantage of using a cement-retained crown instead of a screw-retained crown?

Allows for easy correction of angulation during crown placement (correct)

Provides better resistance and retention form

Ensures immediate and perfect seating of the crown

Reduces the chances of developing complications after crown placement

In case of drifting teeth, why is it preferable to use a cement-retained crown rather than a screw-retained crown?

Ensures better resistance and retention form

Reduces the chances of crown fracture during placement

Provides immediate and perfect seating of the crown

Allows for angulation adjustment to prevent gaps between teeth (correct)

How does the use of an abutment in cement-retained crowns contribute to proper crown placement?

Increases the chances of crown fracture during placement

Corrects the angulation for optimal crown seating (correct)

Compromises the resistance and retention form

Reduces the longevity of the crown

What limits the ability to correct angulation when using screw-retained crowns?

The fixed seating orientation of screw-retained crowns Signup and view all the answers

How does cement-retained crown placement help prevent the formation of black triangles between teeth?

By allowing adjustment of angulation for proper seating Signup and view all the answers

According to the information provided, which of the following statements is true regarding screw-retained crowns?

They have a higher risk of fractures in the areas surrounding the screw access hole. Signup and view all the answers

What is the primary reason cited for the difficulty in placing crowns in the posterior region?

The jaw acts as a class three lever, with less space available in the posterior region. Signup and view all the answers

Which of the following statements about cement-retained crowns is true based on the information provided?

They are less susceptible to occlusion-related issues due to the absence of a screw access hole. Signup and view all the answers

What is the primary consideration when adjusting occlusion for dental crowns?

Ensuring proper contact patterns to distribute forces evenly across the crown. Signup and view all the answers

What is one reason why working with a cement-retained crown can be challenging according to the text?

The crown has a smaller profile compared to a screw-retained crown. Signup and view all the answers

According to the information provided, which of the following statements about resistance and retention form is true?

The text does not provide specific information about resistance and retention form for dental crowns. Signup and view all the answers

Based on the text, what does historical literature suggest about screw loosening for cement-retained crowns?

It happens less frequently than with screw-retained crowns. Signup and view all the answers

What is highlighted as a major disadvantage of cement-retained crowns in the text?

Increased likelihood of restoration failure. Signup and view all the answers

How does the size of a cement-retained crown affect the difficulty of placement according to the text?

It adds to the challenge of proper fitting due to its small profile. Signup and view all the answers

Why does the text mention that occlusion adjustments play a critical role in the performance of cement-retained crowns?

To emphasize that occlusion impacts the rate of screw loosening. Signup and view all the answers

Which of the following is NOT a disadvantage of screw-retained crowns?

Difficulty in retrieving the crown Signup and view all the answers

What is the primary advantage of cement-retained crowns over screw-retained crowns?

Improved esthetics, especially in anterior regions Signup and view all the answers

If a patient reports that a screw-retained crown is getting loose a week after placement, what is the most likely reason?

The occlusion was not adjusted properly Signup and view all the answers

Which of the following statements about resistance and retention form is correct?

Cement-retained crowns have better retention form than screw-retained crowns Signup and view all the answers

What is the primary concern with leaving residual cement behind for cement-retained crowns?

Increased risk of peri-implantitis Signup and view all the answers

Why is it important to consider the long axis of the dental implant when designing crown placement?

To avoid unfavorable forces and restorative complications Signup and view all the answers

What is the main concern associated with a large degree of deviation in dental implant placement?

Risk of screw loosening and bone loss Signup and view all the answers

How does tilting the implant affect the lingual area of the crown?

It increases the lingual surface area Signup and view all the answers

What is a significant disadvantage of a screw-retained crown compared to a cement-retained one?

Increased susceptibility to screw loosening Signup and view all the answers

How does improper crown placement increase the risk of restorative complications?

By causing unfavorable forces and screw loosening Signup and view all the answers

Why is it important for the transition from the implant platform to the gingival margin to be at least three millimeters?

To prevent food from getting stuck in a concave transition. Signup and view all the answers

Why is it ideal for dental implants to be placed parallel to the long axis of the tooth?

To reduce the risk of bone loss and restorative complications. Signup and view all the answers

What type of profile is preferable for the emergence of crowns in dental implants?

Convex Signup and view all the answers

Why is it crucial for the implant placement to be directly underneath the central fossa of the tooth?

To direct forces on the crown during restoration. Signup and view all the answers

What is the purpose of ensuring that the crown has a height of contour?

To simplify cleaning and maintenance. Signup and view all the answers

Which type of crown is more likely to lead to plaque and food accumulation around the implant?

Concave crown Signup and view all the answers

In what scenario would a concave transition from the implant platform to the gingival margin be acceptable?

To match a concave crown's shape. Signup and view all the answers

Why should all implants ideally be placed parallel to the long axis of the tooth?

To prevent bone loss and restorative complications. Signup and view all the answers

Why is it important for a crown to have a convex height of contour?

To ease cleaning and maintenance. Signup and view all the answers

What type of dental crown is most suitable for preventing plaque buildup around an implant?

Convex crown Signup and view all the answers

What is the primary reason the speaker emphasizes the difficulty in ensuring all cement is removed when placing a cemented crown?

The cement can be difficult to visualize on X-rays due to the opacity of the implant. Signup and view all the answers

According to the speaker, what is a key limitation of using two-dimensional X-rays to evaluate the fit of a cemented crown?

Two-dimensional X-rays cannot show if cement is present on the back side of the implant. Signup and view all the answers

What is a key advantage of using a screw-retained crown over a cement-retained crown, as implied by the speaker?

Screw-retained crowns eliminate the risk of leaving behind residual cement. Signup and view all the answers

According to the speaker, what is a potential consequence of leaving behind cement when placing a cemented crown?

Increased risk of developing peri-implant inflammation. Signup and view all the answers

What does the speaker suggest as a solution to the difficulty in ensuring complete cement removal when placing a cemented crown?

Using a screw-retained crown instead of a cement-retained crown. Signup and view all the answers

Study Notes

Porcelain Fractures and Screw Retention

Having a hole in the middle of the crown can lead to compromised areas around the screw, making them prone to micro fractures and eventual fractures.
Cement retention eliminates the risk of micro fractures and fractures.

Posterior Region and Jaw Lever

The jaw is a class three lever, with the least amount of room in the posterior region and the most amount in the front.
Fitting a crown in the posterior region can be challenging due to limited space and the need for precise angulation.

Screw vs. Cement Retention

Screw retention allows for easier manipulation in the posterior region.
Cement retention provides better esthetic results, but can be more difficult to correct angulation.
Cement retention reduces the risk of screw loosening, but may lead to restorative failure before the abutment shows any signs of failure.

Advantages and Disadvantages of Cement Retention

Advantages: easier to correct angulation, better esthetic results, and reduced risk of screw loosening.
Disadvantages: difficulty in retrieving the crown, potential for cement to be left behind, and compromised esthetics.

Disadvantages of Screw Retention

Difficulty in correcting angulation, potential for screw loosening, and compromised esthetics.
Advantages: easy to retrieve, and less risk of cement being left behind.

Implant Placement and Angulation

Ideally, implants should be placed parallel to the long axis of the tooth to direct forces favorably and reduce bone loss and restorative complications.
Large degrees of deviation can lead to unfavorable forces, less restorative material, and compromised esthetics.

Cantilever and Emergence Profile

A cantilever is a bridge-like structure that requires at least three millimeters of space from the implant platform to the gingival margin.
The emergence profile should be concave to allow for cleaning and to prevent plaque and food accumulation.

Leaving Cement Behind

Leaving cement behind is a major cause of peri-implantitis.
It can be difficult to identify and remove excess cement due to its opacity and 2D representation on x-rays.
It is essential to ensure that all cement is removed to prevent complications.

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Description

Test your knowledge on dental crowns and the risk of porcelain fractures. Learn about the impact of occlusion and improper adjustments on crown integrity.