CHAPTER 43 Flashcards
must withstand biting and chewing forces
mechanical
any push or pull on matter is called
force
types of stress and strains
tensile
compressive
shear
pulls and stretches material. two forces applied in different difrections
tensile stress
two forces applied in the same direction (ex: chewing is a type of this stress)
compressive stress
two forces of material parallel to each other sliding in opposite directions. ex: clenching teeth, bruxism
shear stress
the measure of the capacity of a metal to be stretched or drawn out by a pulling or tensile force without fracturing
ductility
the most malleable metal
gold
change in temp in the oral cavity resulting from ingesting hot or cold products leads in size changes in the material. Will result in expansion and contraction.
thermal changes
happens when there are two different kind of metals inside the patients mouth
electrical properties / galvanic shock
the mechanical property of a dental material. A permanent restoration must have enough _______ to resist indentation, scratching, or abrasion
hardness
the reaction that occurs within a metal when it is exposed to corrosive factors such as temperature, humidity, and saline.
corrosion
the degree to which a substance will dissolve in a given amount of another substance
solubility
measure of the capacity of a metal to be stretched or drawn out by a pulling or tensile force without fracturing
ductility
measure of the capacity of a metal to be extended in all directions by a compressive force, such as rolling or hammering.
malleability
thermal changes are of major concern for two reasons
- contraction and expansion
- need to protect pulp from thermal shock from extreme differences in temp.
It is essential that the tooth structure and the restorative material have, as nearly as possible, the same ____ of contraction and expansion.
rate
conditions that cause galvanic shock
two different metal composition in the mouth
saliva = good electricty conductor
The surface discoloration that we see in older amalgam restorations in the mouth is referred to as
tarnish
For a dental material to have specific mechanical properties, steps must occur in the application of the dental material. Techniques used in the placement help create the following effects.
flow
adhesion
retention
curing
the ability of two unlike materials to
adhere to each other.
adhesion
Characteristics of a dental material that will affect the adhesion process
wetting,
viscosity,
surface characteristic
film thickness
the ability of a liquid to come into contact with a solid surface, and the small irregularities that may be present.
wetting
is the property of a liquid that causes it not to flow easily.
viscosity
is the ability to hold two things firmly together when they will not adhere to each other naturally.
retention
a setting process of a dental material that is initiated by a chemical reaction or by a light in a blue wave spectrum
curing
the technical name for silver fillings
amalgam
Amalgam alloy powder is composed of the following metals:
silver
tin
copper
zinc
A high-copper alloy is made up of
40% to 70% silver,
8% to 28% copper,
15% to 30% tin.
composed of gallium, indium, and tin and was approved by the ADA, but it has not been researched for its potential
galloy
When mercury is combined with other materials in dental amalgam, its chemical nature changes so that it is essentially harmless. T or F
True
the process by which mercury and alloy powders are mixed together to form the mass of amalgam needed to restore the tooth
amalgamation, trituration
The amalgam is carried to the tooth by the amalgam carrier and placed in increments into the prepared tooth, with each increment condensed immediately with the use of:
amalgam condenser
tool used to smooth the amalgam, making sure that no irregularities are present in the restoration
burnisher
Composition of Composite Resins
organic resin matrix
inorganic fillers
coupling agent
tooth coloured pigments
resin matrix component also referred to as BIS-GMA
dimethacrylate
the foundation of resins
BIS-GMA
adds the strength and other characteristics needed in a restorative material. (reflects light for a more esthetically pleasing material)
filler
Composites are classified by particle size as :
megafill
macrofill
midifill
minifill
microfill
Composites that have a combination or mixed range of particle sizes are referred to as:
hybrids
the process by which resin material is changed from a pliable state (in which it can be molded or shaped) into a hardened restoration. (occurs with light curing)
polymerization
The exact curing time depends on the following:
manufacturers instructions
shade of restorative material
thickness and size of restoration
have the ability to adhere CHEMICALLY to teeth and not mechanically
glass ionomer
most unique feature of ionomer
releases
fluoride after the final setting.
The type of ceramic most often used in dentistry
porcelain
one that is fabricated outside the mouth by a dental laboratory technician. These restorations, also referred to as castings,
indirect restorative materials
Composition of Whitening Materials
carbamide peroxide
hydrogen peroxide
Teeth become discolored and stained for many reasons including :
aging;
consumption of staining substances such as coffee, tea, colas, and tobacco;
trauma;
use of tetracycline (antibiotic);
excessive fluoride;
nerve degeneration;
aging of restorations.
glass ionomer is especially desirable for the following applications:
primary teeth
final restorations
sealants
core material for buildups
a term in dentistry that describes the ability to remove decay or disease and bring back the proper function of a tooth.
restorative
council formed to ensure that standards and strict specifications are followed by dental material manufacturing companies when a new dental material is developed
Council on dental materials instruments
the change or deformation of a material as the result of stress.
strain
the internal resistance or force that can cause distortion
stress
Indications for Using Dental Amalgam
- Primary and permanent teeth
- Stress-bearing areas
- Small to medium-sized cavities in the posterior teeth
-Severe destruction of tooth structure - cast-metal, metal-ceramic, and ceramic restorations
-poor dental hygiene commitment - problematic moisture control
- cheaper cost
Contraindications to the Use of Dental Amalgam
- esthetics
- allergy to mercury or other amalgam components
-When a large restoration is needed and the cost of other restorative materials is not a factor
Composition of Dental Amalgam
equal parts of mercury (43% to 54%)
amalgam
alloy powder (46% to 57%)
designed to cover the major portion, if not the entire clinical portion, of a tooth or several teeth for a longer period.
provisional restoration
Cautions for Placing Glass Ionomers
• Avoid water contamination/contact with the material.
•glossy appearance has disappeared=the setting stages have begun.
• Protect the matrix band from the material
1:1 ration mercury is called
eames technique
Noble metals used for cast restorations consist of
gold
palladium
platinum
this composite is supplied as a hybrid or nanofilled composite with enough filler included to make the material wear resistant.
flowable composites
these composites resemble flowable composites but have the viscosity to allow the material to flow into the pits and fissures of the tooth surface.
sealant composites
types of composites most often today. They contain a mixed range of particle sizes.
hybrid composites
this type restoration is designed to maintain or restore function and keep the patient comfortable for a limited time.
temporary restorative materials
If a tooth has lost a filling or has a small pit within the enamel, an_______ would be selected.
IRM
- Restoration of primary teeth (when permanent teeth are 2 years or less from eruption)
- Restorative emergencies
- Caries management programs
- Placement as a base
common uses of what :
IRM
