Cementation Techniques Flashcards
What are some unknowns with Zirconia
Longevity is unknown
Low temperature degradation - because it’s metastable, there is concern about transforming over time and creating flaws that lead to fractures
Stress corrosion
How does a stress corrosion occur?
Under function a load is applied Stress occurs at the underside of the crown Existing cracks are strained Water enters and reacts Crack extends over time
Stress corrosion
Mechanism by which the strength of ceramics is reduced in a moist environment
Caused by the reaction of water at the area the track tip resulting in an increase in crack size
With weaker ceramics (Porcelain, Empress, eMAX) what should you do to improve strength?
They should be bonded with resin cement to improve strength
T/F - Stronger ceramics (Inceram, ProCera, LAVA), are difficult to bond
True - they’re difficult to bond, but strong enough to use conventional cements
What are the types of cements?
Water based cements
Resin based Cements
What are different types of water based cements?
Zinc phosphate
Polycarbozylate
Glass Ionomers
Resin ionomers
What are different types of resin based cements?
Composites
Compomers
Numerous products based on composite resin formulations with less fillers
What does a cement do?
Fills the gap between the tooth and the crown
Some connection between the tooth and crown (mechanical and chemical)
What is the ideal film thickness of a cement?
Low thickness
What is the key working time of a cement?
Long
What is the key setting time of a cement?
Short
What is the ideal compressive strength of a cement?
High
What tooth structure should a cement be similar to?
Dentin
What is the ideal pulp irritation of cement?
Low - none
What is the ideal solubility of cements?
Very low - none
What is the ideal microleakage of cements?
Very low - none
What is the ideal retention of cements?
High
What types of cements should be used with metal or metal-ceramic crowns?
Water based cement
zinc phosphate, resin modified GI
What types of cements should be used with ACCs?
It depends
Silica based ACC (weaker) = resin cements
Zirconia based ACC (stronger) = water based or resin based
What is the connection of ceramic strength and opacity?
More opaque = stronger
What is the correlation of ceramic strength and cement strength?
Weaker ceramics need a stronger cement
Can use a weaker cement with a stronger ceramic
How do you etch dentin?
Dentin is etched with 35% phosphoric acid, or self etch adhesive/cement
Etch is rinsed and excess water removed
Why is the etch step being removed from many resin systems?
Because it can result in post-op sensitivity
Self-etching adhesives
Will etch dentin during adhesive application
This minimizes chances of sensitivity, but may form a weaker “bond”
T/F - Zirconia based ceramics are etched normally?
False
T/F - Resin cement chemically attaches to both the adhesive and the silane
True
Conventional Cement
Weak mechanical lock
Chelation (ionic bond)
Phosphate Ester Based Cement
Mechanical bond is minimal
Stronger ionic bond than carboxylic acid
