Dental Material Flashcards
What are the 3 types of adhesion?
Micromechanical - etch
Chemical adhesion - cements containing polyacids.
Adhesion through wetting - Dentine bonding agent.
What is an example of micromechanical adhesion?
Composite
What is an example of chemical adhesion?
Amalgam/GIC
Why do you etch enamel?
Prisms are cut a way which exposes the maximum surface area of the enamel
What is the aim of dentine bonding?
To form a hybrid layer of dental tags through the collagen network.
What is dentine bonding effected by?
The presence of a smear layer, can’t be too dry as the collagen network will collapse.
What is the depth of cure of cimposite?
2mm
In composite what does a large partical size mean?
That the restoration will be less aesthetic.
What can glass ionomers be used for?
Restorative filling
Luting cement
Lining
How long does a GI restoration take to set?
24 to near completion and 3 months to reach a final set.
Advantages of GI?
Adhesive
Bonds to moist tooth
Good marginal seal
Thermal expansion is similar to that of a tooth.
Able to release and take up fluoride.
Disadvantages of GI.
Easily dissolve away.
Matt and dull
Low wear resistance.
What does amalgam contain?
Silver and tin titurated with mercury
Why does amalgam need to contain less than 50% mercury?
To maintain best properties.
WILL CAUSE DISSOLUTION IF MORE
What are the advantages of amalgam?
Good compressive Strength
Good wear resistance
kind to opposing teeth.
EAsy to use
Antibacterial
Chemical set
Cheap
Radiopaque
What are the disadvantages to amalgam?
None adhesive
Weak in thin sections
Thermal conductor
Not tooth coloured
What are the properties of calcium hydroxide?
Soluble in water
Low compressive strength
Not adhesive
pH of 11-12
Bacteriostatic
Promoted tertiary dentine.
What are the properties of zinc oxide and eugonol?
Sedative effect
Not to be used under resin based bases
Not strong
Non adhesive
Properties of resin modified glass ionomer?
Low set solubility
High fracture toughness
Strongest of all bases
Fluoride release properties.
Properties of traditional GI
Chemical bond to tooth
High early solubility
Anti-caries
Releases fluoride
Fluoride reservoir
Low solubility
What are the properties of an ideal liner?
Perfect insulator of pulp
Compressive strength
Biocompatibility
Cheap
Adheres to tooth
Expands and contracts with tooth
Does not degrade in oral environment
Not technique sensitive.
