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Silver paste was first mentioned by?
the Chinese in 659 AD
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In the year ___, in France, silver shavings from coins were mixed with mercury to form a sloppy paste.
1800
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In 1895, ___ developed the first viable amalgam formula
G.V. Black
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Certified” materials are used to:
- Replace or restore lost tooth structure
- Prevent decay
- Take impressions
- Finish, polish, clean a filling or prosthesis
- Replace lost soft tissue
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Food and Drug Administration (FDA)
- Protects the public
- Controls & regulates
- ✓efficacy
- Safety
- Meets standards
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International Standards Organization (ISO)
Set standards used to develop specifications and testing on am international level
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Materials used must be:
- biocompatible
- durable
- nonreactive in acid or alkaline conditions
- compatible with other materialsesthetically acceptable
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Biocompatibility:
- there is NO adversity to living tissue
- Postoperative sensitivity
- Toxicity
- Hypersensitivity
- Documentation
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Biomechanics:
the principles of engineering and biological systems to the design of new dental materials
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Force =
mastication= Normal masticatory force on the occlusal surfaces of molar teeth averages 90 to 200(psi) pounds per square inch
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Types of forces:
- Tensile
- Compression
- Torsion
- Bending
- Shear
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-
-
-
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Stress =
the internal force that resists an applied force
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Strain =
the resulting distortion
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-
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If the stress within the object can not take the applied force, it will
crack = Strain = distortion occurs
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pH of saliva is
6.2 to 7.0
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Material selection (metals especially) suffer from the effects of
moisture and acidity
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Tarnish and Corrosion occur
[therefore leakage is an issue]
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When the current stimulates the pulp it is called
galvanic shock
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Galvanism:
An electrical current transmitted between twodissimilar metals in a solution containing electrolytes
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These 3 elements will produce and electric current (Galvanism)
metals + acid + moisture
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Temperature effects:
- Expansion
- Contraction
- Percolation [gap openings] can occur
- Thermal conductivity
- CTE = coefficient of thermal expansion =
- heat = expansion\ cool = contraction\ CTE is the measure of these changes in volume or length in a given material
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Which is the better conductor of temperature?
Gold or composite
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MICROLEAKAGE
When fluids, microorganisms, and debris from the mouth penetrate the outer margin of the restoration and progress down the walls of the cavity preparation.(not desirable)
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Retention =
- maintain position w/out displacement
- Mechanical or chemical
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Mechanical retention =
undercuts in the preparation
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Chemical retention =
obtained through adhesion or bonding
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Forms of retention
- Acid etch
- Retention grooves
- Microabrasion etch 1st\ aluminum oxide forced onto the tooth by compressed air.
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Wetting:
The ability of a liquid to wet or intimately contact asolid surface.
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The three components of color
hue, chroma, & value
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Hue is
the dominant color
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Chroma
- intensity \strength or lack of [high\low]

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Value
- how light or dark a color is [dark\light]

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What are some ways of detecting restorative materials?
- Location
- Tactile sensitivity
- Radiographs
- Air
- Magnification
- Illumination
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Primary bonds
- Strongest [because they involve the exchange of electrons]
- Three types:
- Ionic:[1 e- exchange = brittle/broken], covalent:[2 e- exchange = strong/hard/high melting point]
- Metallic:[multiple e- cloud [-] attraction]
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Secondary bonds
- Much weaker
- No e- sharing
- Much deformation and fracturing
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3 basic physical structures of a material
- Solid: has shape and volume
- Liquid: has volume but not shape
- Gas: has neither volume nor shape
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Solid:
has shape and volume
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Liquid:
has volume but not shape
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Gas:
has neither volume nor shape
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Plaster
- is a combination of a solid and a liquid
- Most materials are mixtures of more than one state of matter.
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Linear coefficient of thermal expansion
- describes how the size of an object changes with a change in temperature; i.e.. ice
- + a measure of the change in length of an system over a given temperature range
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Thermal expansion
is the tendency of matter to change in volume in response to a change in temperature
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If a material is going to be sitting in the human mouth it must be able to withstand:
Mechanical and thermal changes
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Mechanical:
- strength to withstand biting and chewing forces
- Force load
- Stress
- Tensile
- Compressive
- Shear
- Strain
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Thermal Change
- Contraction & Expansion
- *Thixotropic
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Thixotropic =
liquid[s] being able to flow more easily under mechanical forceCertain gels or fluids that are viscous in static conditions will become less viscous when shaken, agitated, stressed
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Solubility/ Soluable
- How much a material dissolves
- Able to dissolve in fluids
- Measured as:
- HighLow
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DEFORMATION:
change in shape or form
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FLEXIBILITY:
ability to bend considerably with small stress resulting
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ULTIMATE STRENGTH:
maximal stress a material can withstand without rupture or fracture
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MALLEABILITY:
ability to withstand permanent deformation under a compressive load without rupture. (Gold is a malleable metal)
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TOUGHNESS:
ability of a material to resist fracture
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BRITTLENESS:
property of being easy to break or rupture (opposite of toughness)
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COHESION:
the force which causes attraction between like molecules
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ADHEREND:
the material to which the adhesive is applied (receiver of the adhesive)
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WETTING:
spreading of a liquid over a rough surface. Promotes adhesion by providing more intimate contact between adhesive and adherend.
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DUCTILITY:
the ability of material to withstand permanent deformation under a tensile load without rupture
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EXOTHERMIC:
a chemical reaction that gives off heat
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MECHANICAL RETENTION :
how a material is held in place by means such as the shape of the cavity preparation, etching the surface or placing retentive groves
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ELASTICITY:
(a substance) deforms under stress, but then returns to its original shape after the removal of the stress
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ELASTIC LIMIT:
the maximum stress a structure can withstand without being deformed permanently
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MODULUS OF ELASTICITY:
(Young’s Modulus) that property which relates to the rigidity or stiffness of a material under stress
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A stiff material:
does not deform much when a stress is applied, it has a high elastic modulus. [it can withstand the strain]
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Flow=
Molecules in a liquid state
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The viscosity of a liquid is
- its resistance to flow.
- The thicker the material, the harder it is for the material to flow.
- Film thickness [aka.the minimum thickness attainable] is important when dental cements are used
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Retention is effected by
viscosity
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low viscosity =
thin fluids
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high viscosity =
thick fluids
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Therapeutic
used in the treatment of disease and include materials such asMedicated basesTopical applications for periodontal disease
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Preventive
directed toward the prevention of disease and the promotion of oral health.Preventive materials includeSealants
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Restorative
makes up the largest classification and include fillings, crowns, implants, etc.Restorative materials are further classified asDirectIndirect
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Things to consider about materials
- Reaction:
- Set mixing time
- Chemical
- Light
- Dual-cure
- Manipulation:
- Through
- Directions
- Accuracy
- Shelf Life:
- Storage
- Manufac. date
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OSHA =
Occupational Safety and Health Administration
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CDC =
Center for Disease Control
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OPIM =
Other Potentially Infectious Materials
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PPE =
Personal Protective Equipment
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NFPA =
National Fire Protection Association
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MSDS =
Material Safety Data Sheets
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EPA =
Environmental Protection Agency
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ADA =
American Dental Association
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GHS =
Globally Harmonized System
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OSHA Occupational Safety and Health Administration
- US Department of Labor agency
- Mission: protect workers: physical, chemical and infectious diseases while at work
- Set standards: in work facilities [exposed to human body fluids]
- This OSHA standard is the ‘Bloodborne Pathogens Standard’:
- “Avoiding occupational exposures to blood is the primary way to prevent transmissions in health-care settings”. CDC (Center for Disease Control) 2003
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OSHA: required Exposure Control Plan
Blood-borne/Hazardous Materials
- Employee training, safety, and documentation requirements
- New employee training within 30 days,
- when new chemicals introduced,
- once a year refresher
- Records are kept for 5 years or whiled employed + 30 days
- Exposure determination: low high risk
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To control possible exposure:
- Infection control
- Universal precautions
- Standard measures used
- Post-exposure follow-up
- PPE = Personal Protective Equipment
- Housekeeping/laundry
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OSHA regulations:
- PROTECTS EMPLOYEE [workers] and patient
- Disposal of biohazardous (regulated) waste
- Hired companies
- What about PCC?
- Offering of Hep.B Vaccination, and yearly TB testing
- Mandated training for dental Employees
Inspections of dental facilities as it relates to worker safety
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PPE: Personal Protective Equipment
- Gloves: utility and examination.
- Masks [particulate matter]
- Gowns. Long sleeved & fluid resistant.
- Fabric or disposable.
- Safety glasses. Protect from side and front.
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Hazardous Materials in the Dental Office
Exposure to :
- particulate matter
- Mercury
- toxic effects of chemicals
- airborne contaminants
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Pathways of exposure:
- Inhalation
- Absorption through the skin
- Ingestion
- Invasion directly through a break in the skin
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Hazardous chemicals can
- Catch fire
- React or explode when mixed
- Be corrosive or toxic
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Which is the most severe pathway?
inhalation
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GHS
- Product identifier
- Signal word
- Hazard systems
- Precautionary statements
- Pictograms
- Supplier info.
- Supplemental info.
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NFPA
Material identityHazard warningsSupplier information
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NFPA (National Fire Protection Association) Chemical Hazard Labels
- Blue – health
- Red – flammability
- Yellow – reactivity
- White – what PPE needed for specific hazard (A-X)
4 = extreme hazard
3 = high hazard
2 = moderate hazard
1 = slight hazard
0 = no hazard
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Health (Blue)
4 Danger: may be fatal on short exposure. Specialized protective equipment required
3 Warning: Corrosive or toxic. Avoid skin contact or inhalation
2 Warning: May be harmful if inhaled or absorbed
1 Caution: May be irritating
0 No unusual hazard
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Flammability (Red)
4 Danger: Flammable gas or extremely flammable liquid
3 Warning: Flammable liquid flash point below 100° F
2 Caution: Combustible liquid flash point of 100° to 200° F
1 Combustible if heated
0 Not combustible
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Reactivity (Yellow)
4 Danger: Explosive material at room temperature
3 Danger: May be explosive if shocked, heated under confinement or mixed with water
2 Warning: Unstable or may react violently if mixed with water
1 Caution: May react if heated or mixed with water but not violently
0 Stable: Not reactive when mixed with water
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Special Notice Key (White)
W: Water Reactive
Oxy: Oxidizing Agent
Inhalation hazard
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GHS scope & Benefits
- Scope:
- Covers: all haz. Chemicals; substances; diluted solutions; mixtures; pharmaceuticals; food additives; cosmetics;
- Work exposure
- Transportation
- Enhanced Protection of peoples and environment
- Facilitation of international trade in chemicals
- Insuring more sound management of chemicals
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Chemical manuf. compliance dates:
June 1, 2015 complete modifications
Dec. 1, 2015 = last day to ship under “Old System”
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Employer compliance dates:
- Dec. 1, 2013 = new labels & SDS
- June 1, 2016 complete GHS training
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Per OSHA standards Every container with chemicals or materials needs to be labeled with:
- Name
- Hazard label
- Correct number level
- Expiration date
- Manufacture if changed into different container.
- Original containers need to have expiration date
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Eye wash, body wash station
Flush area with water immediately for at least 5 minutes.
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SDS (Material Safety Data Sheets) SDS Explanation
As an operator you must be able to:
- Discuss requirements & standards
- Explain the hazards of the chemicals
- Protection measures
- Label accuracy
- Record keeping
- Differentiate/ maintain bio–living- aerosols
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