Dental Materials Flashcards
What do material characteristics determine
Selecting the most suitable material
Preparation/placement method
Dentist/patients expectation
Longevity
What are the different material types
Restorative
Impression
Dentures
Metals and alloys
What are restorative materials for
They are for after dental caries have been removed to fill the cavity
How does the material chosen influence cavity design
Amalgam is held in position mechanically whereas composite bonds therefore you can remove minimal enamel
What is creep in reference to amalgam
Low level forces are applied and overtime this causes the material to protrude around the margins which makes in vulnerable to fracturing
Why does a fractured filling require replacement
A fracture allows fluid and bacteria to reach the dental pulp
How can composite resin be made more/less viscous
Depending on glass particle filler composition
What does acid etching do
Grooves the enamel allowing material to interlock with it
What is used for the acid etch technique
30% phosphoric acid applied for 20 seconds
What is sheer strength
Strength against forces trying to slide the material across the tooth
What is compressive strength
How much the filling can bear before it fractures
What is glass ionomer cement
Bonds to enamel
Releases fluoride which helps prevent secondary caries
Which material has the greatest compressive strength
Amalgam
Which material has the greatest tensile strength
Composite
Why is the thermal expansion properties of a material important
Restorative material should expand/contract as the tooth does otherwise micro leakage occurs which can result in secondary caries
What is the key component of impression materials
Viscosity
What does low viscosity impression material allow
Most accurate record of tooth surface detail but less stable after setting so can warp the shape in time resulting in distorted record of patients dentition
What does high viscosity impression material allow
Most dimensionally stable after setting and removing
How is the low viscosity impression material applied
It is placed around individuals teeth
The initial impression tray is inserted
What is the two step technique
When high and low viscosity materials are used in combination
Why is the elasticity of impression material important
When removing the impression material the bottom part must be able to fit over the bulb of the tooth
The material flares out so you can pull it outwards
Ideally it would have the same shape as the tooth but it doesn’t so the impression is technically not 100% accurate
What is a positive replica
Clinical will put gypsum into impression resulting in a dental cast
What is an acrylic resin dentures
All made out of acrylic
What are metals and alloys used for
Partial dentures
Frameworks
Orthodontic wires
Denture bases
