100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
CDT Exam Part 2 Questions & Answers 2024/2025 $8.99   Add to cart

Exam (elaborations)

CDT Exam Part 2 Questions & Answers 2024/2025

 8 views  0 purchase
  • Course
  • CDT
  • Institution
  • CDT

CDT Exam Part 2 Questions & Answers 2024/2025 If the metal's surface is sharp or uneven, - ANSWERStensile stresses are created in the porcelain as it cools and may cause the veneer to fail Opaque firing cycle - ANSWERS-Using a #6 sable brush, slightly moisten the casting with fluid and appl...

[Show more]

Preview 2 out of 11  pages

  • August 3, 2024
  • 11
  • 2024/2025
  • Exam (elaborations)
  • Questions & answers
  • CDT
  • CDT
avatar-seller
Bensuda
CDT Exam Part 2 Questions & Answers
2024/2025

If the metal's surface is sharp or uneven, - ANSWERStensile stresses are created in the porcelain as it
cools and may cause the veneer to fail



Opaque firing cycle - ANSWERS-Using a #6 sable brush, slightly moisten the casting with fluid and apply
opaque, condense

-Fire the casting 600 to 960C and 32C per minute in a vacuum



Removing contamination from a metal die - ANSWERSIf a high-gold content alloy framework has been
finished on a metal die (copper, silver, or amalgam), boil it in nitric acid for 1 minute and then pickle it in
hydrochloric acid



Pretreatment of the metal surface before porcelain application - ANSWERS-Treatment varies with the
base-metal elements, such as tin, indium, and iron, to precipitate on the surface and produce an oxide
film.

-Alloys that contain greater amounts of base-metal elements (notably nonprecious alloys) produce
thicker oxide layers

-in contrast, high-gold content alloys with far lesser amounts of base elements produce fewer surface
oxides

-for this reason bond strength varies greatly depending on the types of alloy and surface pretreatments



Order of procedures for pretreating metal surface/Oxidizing - ANSWERS1. Surface grinding

2. Ultrasonic cleaning with distilled water or steam cleaning

3. heating under vacuum and 1040*C for 2 minutes

*4. Deoxidizing with acids or air abrading with aluminum oxide

*5. Heating at atmospheric pressure at 1040*C for 2 minutes (4 & 5 are only done on nonprecious alloys
that produce an excessive amount of oxides, never do this to high-gold content alloys)

, Surface grinding (pretreating metal) - ANSWERS-normally considered to be the last step of metal
finishing, surface grinding is done to remove defects and make final adjustments

-increases the mechanical bond between the porcelain and metal

-best accomplished by using a carbide bur and grinding in only one direction

-*if you leave the surface rough, it can create stresses within the porcelain veneer

-**From this point on, handle the castings with forceps to prevent contaminating the porcelain-bearing
surfaces with oil and dirt from your fingers



Ultrasonic Cleaning (pretreating metal) - ANSWERS-the purpose is to clean the metal of any abrasive
particles, dirt, and oils that may have attached to the surface during the grinding process

-if oily residue remains on the ground surface, it will bake on the metal surface as a contaminant

-steam cleaning is also effective



Heating Under Vacuum (pretreating metal)/ Oxidizing - ANSWERS-the term "oxidation" describes the
heating process used to produce a controlled oxide layer on the metal's surface and to dispel gases
absorbed by the metal during casting

-if the gasses aren't released before the porcelain is applied, they could cause the opaque to bubble at
the interface between metal and porcelain

-they will migrate to the top and become visible

-the resultant holes can be repaired; but each time the porcelain is fired under vacuum, the risk of
escaping gas increases

-heating the framework under vacuum to 1040*C for 2 minutes will drastically decrease bubbling



Deoxidizing (pretreating metal) - ANSWERS-some metal-ceramic alloys produce excess amount of oxides
that decrease bond strength and darken the metal surface

-air abrading the metal surface will deoxidize the castings and, to some extent, expose "fresh" metal for
re-oxidation

-*** DO NOT deoxidize the castings made from high-gold content alloys. These alloys produce fewer
surface oxides and deoxidation could strip the metal surface of its base-metal atoms



On average, the volume shrinkage of porcelains is between ____ and ___ %

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller Bensuda. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $8.99. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

77254 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 14 years now

Start selling
$8.99
  • (0)
  Add to cart