All Ceramic Restorations Flashcards
3 advantages of all ceramic restorations?
- Highly aesthetic.
- Highly biocompatible.
- Certain systems can be provided same day.
3 types of restorations where all-ceramic may be used?
- Veneers.
- Crowns.
- Bridges.
4 disadvantages of all ceramic restorations?
- Mechanical properties (prone to fracture under oral function).
- Require larger reduction in tooth tissue compared to metal.
- High cost.
- Reduced scope for adjustment or repair.
How are dental ceramics often classified? (2)
- By composition.
- By method of manufacture.
Dental ceramic classification by composition (4 types)?
- Glass-based ceramics.
- Glass infiltrated ceramics
- Polycrystalline (non-glass) ceramics.
- Resin-matrix ceramics
What are the types of glass based ceramics (3)? What do these contain?
- Contain glass and filler.
1. Feldspathic glass (filler <17%, high aesthetics yet most fragile).
2. Moderately filled glass ceramics (17-45% leucite based filler).
3. Highly filled glass ceramics (45%-70% leucite or lithium disilicate filler).
What is the effect of high filler on properties (2)?
- Less aesthetic.
- Stronger.
What are the contents of glass infiltrated ceramics? What are its properties (2)?
- Alumina, magnesium or zirconia infiltrated with low viscosity glass.
- Good mechanical properties, reduced aesthetics.
Trade name example of glass-infiltrated ceramics?
In-Ceram.
What are the contents of polycrystalline ceramics (2)? What are its properties (1)
- Contain NO GLASS.
- Alumina or zirconia based.
- Good mechanical properties.
What are the contents of resin matrix ceramics (2)? What is disadvantage?
- Similar to COMPOSITE.
- Ceramic nanoparticles in a resin matrix.
- Limited clinical study on them.
Dental ceramic classification by method of manufacture (3 types)?
- Sintering.
- Hot pressing/ injection moulding.
- Machining.
3 steps to sintering?
- Ceramic powder mixed with water is built to the required tooth shape (on a cast of the tooth preparation).
- Exposure to high temperature.
- Partial melting and fusing of particles.
What is an example of an all ceramic restoration manufactured by the sintering process?
In Ceram
What is hot pressing/ injection moulding similar to?
Lost wax technique.
2 steps to hot pressing/ injection moulding?
- Wax up of the restoration is invested in refractory die.
- Heated block of ceramic in injected under pressure to replace the wax and form the ceramic restoration.
What does CAD/CAM stand for?
- Computer aided design/ computer aided manufacture.
What does machining use?
CAD/CAM machine.
Steps to machining?
- Prepare tooth and take a digital impression and design
- The restoration is milled (soft or hard state) from a block of ceramic (mono or multichromatic blocks available).
What are monolithic all ceramic restorations?
- Machined from a SINGLE BLOCK of ceramic.
What are bilayer all ceramic restorations?
- SImilar to metal ceramic crowns.
- COPING made of tougher highly filled glass ceramic or zirconia.
- More aesthetic FELDSPATHIC porcelain can then be built onto this coping.
What is Lava?
Tradename for machining zirconium crown.
What type of preparation must be avoided (especially for all ceramic restorations)? why?
- Avoid sharp angulation as these can cause STRESS CONCENTRATIONS in the restoration, initiating FAILURE.
Tooth reduction measurements for an anterior Lava crown?
- Incisally/ occlusally: 1.5-2mm.
- Labially: 1-1.5mm. (1mm towards the ADJ).
- Palatally: 1-1.5mm (1mm closer to ADJ).
