Test 1 Flashcards
What are the classifications of dental materials?
Preventative, restorative, and therapeutic
What year was fluorosis first noted?
1901
What is stress
The internal force resisting the applied force
What is strain
The distortion produced by stress
What is tensile force
The stretching of an object
What is flexural stress
Bending stress, which is a combination of tension and compression
What is compressive stress
Pushing an object together
What is shearing stress
Sliding in the opposite direction
What is torque
Twisting force
What are soluble materials?
They dissolve in liquid
What is sorption
The ability to absorb liquid
What is corrosion
The deterioration of metal due to chemicals/acid
What is tarnish
When corrosion begins on the surface
What is percolation
When due to temperature the material expands and shrinks so many times that it opens a gap
What is CTE (coefficient of thermal expansion)
The measurement of change in volume/length related to change in temperature
What is thermal conductivity?
The rate that heat flows through a material over time
What is wetting?
The degree to which a liquid adhesive is able to spread over a surface
What is vistocity
The resistance of a liquid to spread (the thickness), which can affect the wetting
What is bonding retention
The ability to maintain position without displacement under stress
What is micro leakage and what causes it?
If a interface is not properly sealed, microorganisms can now get inside, causing sensitivity, decay, and staining
What is galvanism
The electric current being transmitted between two dissimilar metals
What are primary and secondary bonds? What are the types? Which are strongest?
Primary bonds are the strongest bonds, involving the sharing of electrons, while secondary bonds are weaker physical bonds. Ionic (metal and nonmetal), colavent (2 nonmetals), and metallic.
What is thixotropic?
It means that some gels and liquids flow more readily under mechanical force such as mixing
What are preventative materials?
They prevent disease or tooth destruction
What are therapeutic materials?
They reduce disease
What are restorative materials?
They restore tooth structure
What are direct restorations?
They are placed directly into the mouth to form
What are indirect restorations?
They are formed outside of the mouth and placed into the mouth
What are permanent restorations?
They are expected to be long lasting
What are temporary/provisional restorations?
They last short periods of time, up to a few weeks
What are intermediate restorations
Temporary, but could be up to months
What is mixing time?
The amount of time to mix
What is working time?
The time from the start of mix to the initial set
What is setting time
The time it takes to set
What is a bio-aerosol
A cloud like mist containing microbes
What is acute toxicity
Results from high levels of exposure over a short period of time with immediate effects
What is chronic toxicity
Results from repeated exposure of low doses over a long period of time
When should ZOE be used?
ZOE does not have the strength to be a permanent cement or high strength base, so it is used for provisional cements and restorations, low strength bases, and root canal sealers and periodontal dressings.
What cement is commonly used for orthodontics?
Resin cements or glass ionomers.
What is primary consistency?
Less viscous and easily glowing which can be drawn into a 1 inch string, suitable for luting
What is secondary consistency
Thick, putty-like consistency which can be rolled into a ball, suitable for a base
How to mix zinc phosphate and why
Zinc phosphate is mixed on a glass cooling slab in a figure 8 pattern to absorb the heat of the exothermic reaction
How do hybrid ionomers differ from GIC
They have better compressive and tensile strength and reduced solubility. They are recommended for high strength all ceramic or metal based restorations
Uses and advantages of GIC
They are one of the most versatile cements. They are biologically comparable with pulp and act as a fluoride reservoir, are easy to mix, and have moderate strength.
What is luting consistency?
It has low viscosity, which, placed between the tooth and restoration, sets, and firmly attaches the restoration to the tooth.
What is needed to make an alginate impression?
Rubber bowl, spatula, and impression trays
What are the types of elastic materials?
Agar and alginate (hydrocolloids), polysulfides, and silicone rubber materials
What are polyether materials?
A hybrid of polyetheal and polyvinal siloxane
What are inelastic materials?
Dental compounds, impression plaster, zinc oxide eugenol, and impression wax. These are older and not used very often.
What is an irreversible hydrocolloid
Alignâtes are irreversible, meaning they are mixed into a sol state and when setting convert into a gel.
What is a reversible hydrocolloid
Agar is reversible, meaning it starts as a gel and when heated becomes a fluid that turns back into a gel
What are positive reproductions of dental structures known as?
Dental casts
What does “pouring” of a cast refer to?
The process of vibrating the flowable gypsum product into the impression
What is impression plaster?
Type I, rarely used but could be a final impression wash or to mount casts
What is model plaster?
Type II, it is used for diagnostic casts and articulation of stone casts, durable but relatively weak
What is dental stone?
Type III, it is ideal for denture models, orthodontic models, and casts requiring strength
What is dental stone high-strength/low-expansion?
Type IV, referred to as die stones since they are suited for fabricating wax patterns for cast restorations.
What is dental stone high-strength/high-expansion?
Type V, used for base metals, has the highest strength
What is the initial setting time and final setting time for gypsum products
The mixing time is 1 minute, when it is then poured into the impression. When it turns glossy the initial set time is reached, which is 8-16 minutes after starting. Final set time is 45-60 minutes
What are the 2 parts of diagnostic and working casts?
Anatomical and art portion
What are pattern waxes?
Inlay waxes, casting waxes, and baseplate waxes; used in construction of metal castings and denture bases
What is processing wax?
Boxing wax, utility wax, and sticky wax; used to aid in dental procedures
What is impression wax?
Corrective impression wax and bite registration wax. Used to obtain impressions of the oral structures.
