Zirconia Crowns Flashcards
Zirconia is a type of metal which is
long lasting and indestructible. Plus there is no fear about the body rejecting zirconia or displaying an allergic reaction to it. It is safe to use and preferred by many people to porcelain fused to metal crowns.
Zirconia(ZirconiumOxide) is a
white powdered metal used to create dental frameworks for crowns, bridges and other dental substructures. It replaces gold or stainless steel used in the past, creates the appearance of a whiter more translucent tooth.
The originally introduced full-zirconia restorations were not
esthetically acceptable because of their opaque, off-color, and too light characteristics. However, remarkable progress has been made to date. Currently, they are available of numerous colors of zirconia and definitely more translucent.
Zirconia indications
Anterior and Posterior crowns and Bridges
Post and core (Endo)
Implants abutments
Ortho brackets
Zirconia CONTRAINDICATIONS
Reduced inter occlusal space
Deep vertical overlap
Opposing supra erupted tooth
Very short clinical crown
Zirconia ADVANTAGES
Superior esthetics
Easy preparation and cementation
Optimal fit ( CAD/CAM)
High strength (fracture and crack resistance as well as good flexural strength)
Excellent insulating behavior
Biocompatible (no allergic response to date)
Porcelain fused to metal = PFM = MCC
Increase opacity
Porcelain chip off
Marginal discoloration
PFM vs ZIRCONIA vs LITHIUM DISILICATE
Most dentists are reluctant to use any new or moderately proven restoration type for all of their restorations. Porcelain-fused-to-metal is well proven and has had over 50 years of successful use. Lithium disilicate restorations are among the most esthetic restorations in dentistry today and many laboratories are providing them at reasonable prices. Properly fabricated and seated cast-gold alloy restorations are still known to be the longest-lasting crown restorations. I suggest NOT using any new product exclusively until the evidence on the previously discussed materials or products is well proven. Don’t throw away the older, well-known materials.
Zirconia DISADVANTAGES
Expensive
Difficult to reinter vine( posts for endo)
Bond between veneer ceramic and zirconia framework is the weakest component in the layered structure.
Non available longitudinal study
I will recommend Zirconia for
molars and premolar single unit or short spam posterior bridges.
PFM will remain for some
long-span prostheses, precision attachment placement, and other uses.
Unfortunately, cast-gold alloy will continue to
die a natural death due to cost of material, patient demand for tooth-colored restorations, and lack of dentists promoting it.
Posteriors:
better without zirconia, as this makes it difficult to access post (removal is a pain)
Zirconia prep dimensions
1mm chamfer
Occlusal reduction between 1.5 and 2 mm (recommend 1.5 mm for both cusps)
**more occlusal reduction for
bridges
