DM1 - Introduction to Dental Materials Flashcards
What does a dental resin composite consist of?
- resin
- filler
- coupling agent
What is a dental composite?
combination of materials in which the individual components retain their identity and which possess different properties to the components acting alone
what is dental composite used for?
- restorative (filling) material
- special tray construction
what are the properties of fibre rein-forced material?
- consists of fibres of high strength and modulus
- embedded to a matrix
- maintains a distinct interface between components
- kevlar and light weight
dental fibre reinforced materials attempt at what? (4)
- construction and reinforcement of denture bases
- inlays and inlays
- crowns and bridges
- posts to reinforce and restore root treated teeth
why is a knowledge of applied materials required? (3)
- facultative effective use
- permit clinical problem solving
- promote effective dialogue within personnel of profession
what was the Medical Devices Directive changes implemented?
March 2010
What are the legal requirements relating to the prescription of laboratory made dental appliances? (3)
- statement of manufacture offered to all patients receiving dental appliance
- GDC invites patients to ask for such a certificate
- MHRA enforce directive. Failure to offer statement is a criminal offence
what is included in a statement of manufacture?
- patients name and confirmation made for them
- prescribers name and registered address
- technicians name and registered address
- description of the appliance
- confirmation meets legal standards
What is the oral environment subjected to?
- loading to 6Kg
- on/off cyclical forces (fatigue)
- chemicals
- temperature fluctuations
What is the name for the shock absorber which teeth are suspended in?
periodontal ligament
what force intrudes the tooth?
1N
what force flexed the bone and causes pain?
15N
What can pH of the oral environment fluctuate to?
2-12
What materials are used by the dental team?
- gypsum materials (plaster)
- waxes
- polymers
- ceramics
What is the name of the two standards institutions?
- British Standards Institution (BSI)
- International Standards Organisation (ISO)
what is strain?
change in the original length of material and has no units
what is stress expressed as?
Mpa where A is in mm2 and F in newtons
What is the name for the linear region of curve stress/strain? It gives a measure of stiffness
modulus
What is the name of the mechanical property where a force is applied to elongate the rod?
tensile
What is the name for the mechanical property which is not recommended for brittle materials?
comprehensive
What is the name for the mechanical property which is useful for brittle materials where conventional tensile is not applicable?
Diametral tensile strength
What is the name for the mechanical property which has 3 points?
flexural
What is the name for the potential for a material to be drawn out into a wire? It is the difference between the two linear lines
ductility
What does it measure if the graph is shaded under the linear portion?
resilience
What does it measure if the whole graph is shaded?
toughness
What does it measure if the whole graph is shaded?
adhesive failure
What is it called when only one side is broken?
cohesive failure
How do you measure surface roughness?
profilometer
What is the name for the study of viscosity and how it varies with rate of shear and time?
Rheological properties
What defines the chemical reactivity of metals and alloys (an electrolytic property)?
corrosion
how are biological properties tested?
- laboratory screening
- limited lavatory in vivo usage testing
- human randomised controlled clinical trial
what is the idea biological properties of a material? (4)
- non toxic
- non irritant
- harmless to dental pulp
- no carcinogenic potential
