13,14 - Ceramics (slides 1-46) Flashcards
what is a ceramic
any product made form nonmetallic inorganic material that is usually processed by firing at a high temperature
what is porcelain?
a type of ceramic materials originally made by mixing Kaolin, quartz, feldspar and firing them at high temperatures
what are porcelains used for
metal-ceramic and ceramic dental restorations
![](https://s3.amazonaws.com/brainscape-prod/system/cm/171/145/110/a_image_thumb.png?1449381191)
how do we classify ceramics? (3)
by application
by fabrication method
by crystalline phase
classifying by application: what are three applciations for ceramics?
metal ceramic crowns and fixed partial dentures
all ceramic crowns
miscellaneous: ceramic orthodontic brackets, dental implant abutments, ceramic denture teeth
callsification by fabrication: what are ways that ceramics are made?
sintering - the most common method for metal ceramic restorations (sintering is the process of firing the compaced ceramic powder at high temp. It reduces pores and binds particles together increasing the final density (see image of firing in a vaccum, also increses density).
slip casting
heat pressing
CAD/CAM machining
combinations of the above
regardless of the fabrication technique, ceramics are made of what?
a glassy or vitreous phase and one or more ctystalline phases with various amounts of porosity
what causes the wide variation in mechanical and optical properties of porcelain?
variations in the nature of the crystalline phase and the degree of porosity. Increasing crystalline component can improve resistance to fracturing but can also decrease translucency.
Materials for all ceramic restorations have increased what?
amount of crystalline phase. They have more crystalline phase than ceramo-metal restorations to make up for the lost strength of metal, but they are usually more opaque than porcelains used in ceramo-metal restorations with lower crystallinity.
Slides 13-21, I don’t think we need to know, so i don’t include them… These are those charts with the yellow headings that talk about different ceramic materials and who manufactures them and their crystalline phase. look over them if you want.
ceramics are the best material for
matching the aesthetics of a complex human tooth.
what are some general applications of ceramics in dentistry
single and multi unit metal ceramic restorations
all ceramic systems:
inlays, onlays, veneers, crowns
zirconia based (super strong) systems: dental implant abutments, fixed partials
but be careful, they can be brittle, quality is essential
Ceramic is widely used as the veneering material in what?
in metal ceramic crowns and fixed partial dentures.
when porcelain and metal are used together, why is there an intentional sleight mismatch of coefficients of therml expansion (of the porcelain and the metal)?
it enhances the porcelain-metal bond, keeping the porcelain in a state of compression and lessening the chance of fracture.
With regard to metal ceramic restorations, what is good about them?
are they still widely used?
how good is their survival rate?
good: the finished restoration is color stable, tissue friendly, biologically inert, and chemically durable
yes they are
a metal ceramic crown lasts a similar amount of time compared to an all ceramic crown, but the survival rate of a multiunit all ceramic fixed partial prosthesis lasts less time than a metal ceramic one.