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86 Cards in this Set
- Front
- Back
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What are the different types of amalgam?
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Lathe-Cut: Stronger, produced from metal cut by a lathe.
*good for packing and shaping Spherical: Seals interproximal well, produced by spraying metal into cold air. *not alot of strength Admixed: Easiest to work with *combination of the 2 |
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Amalgam is classified by what?
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The shape of their alloy particles
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What are the different types of composites?
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Marofill: large particles, hold up well but stain. Life span of 5 years.
Midfill: works well Microfill: smooth but not enough wear resistance |
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Advantages of Gold
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Resistant to corrosion and tarnish
Thermal expansion similar to the tooth Very biocompatible Last a long time |
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Disadvantages of Gold
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Require skill and attention to detail
Cost more Hard to find a dentist that does gold |
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Setting Time of Alginate
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Normal setting time: 3-41/2 minutes, 2 minutes working time
Fast setting time: 1-2 minutes, 30-45 seconds working time |
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How do you want to remove an alginate impression and why?
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Remove rapidly because it makes it less likely to tear
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The impression will ______ as water evaporates.
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Shrink
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The impression will _______ if placed in water.
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Expand
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It is best to store an alginate impression in what type of environment?
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Humid- least amount of dimensional change
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What are the 3 types of implants and what are their characteristics?
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Transossteal: Drill through the bottom of the jaw up, not very successful, can only use on the mandible.
Endossteus: The kind we use now, where you drill a hole in the bone. Subperiossteus: Metal framework that rests on the alveolar ridge, less invasive than endossteus but less stable. |
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Implants are made of what?
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Titanium
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Know the lost wax technique-
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It is long so I didn't enter it- just read it from the book
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Types of waxes used in dentistry
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Pattern Waxes: used to make inlays, onlays, crowns, pontics, bridges and partial dentures.
Processing Waxes: Used to add bordering to impression trays, usually red and soft. Impression Waxes: Used for edentulous impressions, bite registrations. |
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What is cutting?
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Removing by a shearing off process
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What is Abrasion?
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Wearing away of a surface
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What is finishing?
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Producing the final shape and contour
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What is polishing?
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Abrading the surface to reduce the size of scratches until the surface is shiny
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Types of abrasive agents are?
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Tungsten carbide: Hardest metal, 9-10 on Mohs scale
Carbide: A group of abrasives such as silicone carbide, baron carbide, and tungsten carbide. Emery: Oxide of aluminum, looks like sand. (emery board) 9-10 on Moh's scale. Aluminum Oxide: Replaced emery, example is Shimmer, 9 Moh's scale Tin Oxide: Polishing agent for metallic such as amalgams. 6-7 on Moh's scale. Pumice: Natural glass produced from valcanos, 6 Moh's scale Rouge or Iron Oxide: Used to polish gold |
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Prophy paste contains?
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Pumice, silicone dioxide, zirconium silicate
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Moh's Scale for Enamel, Dentin and Composite?
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Enamel 5 to 6
Dentin 3 to 4 Composite 5 to 7 |
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Resin (composite) hardens by two means what are they?
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1) Autoploymerization or self cure
2) Light initiated polymerization or light cure |
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How is plaster formed?
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NOT cooked under pressure
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How is stone formed?
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Cooked under pressure
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What is adhesion?
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Means binding to something else
*only on 1 surface |
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What is cohesion?
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Binding to itself
*on both surfaces |
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ADA types of stone and plaster
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Type I: Impression plaster, Gypsum
Type II: Model plaster (white) Type III: Dental Stone (yellow) Type IV: Die Stone, low expansion, true to mouth Type V: High expansion, dye stone that shrinks |
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What is an Inlay?
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Within the cusps
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What is an onlay?
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Includes one or more cusps
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What is HUE?
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The dominate color of the object
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What is Value?
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How light or dark
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What is Chromaticity?
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how pure, no white, black or gray. Very vivid.
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What are the types of forces?
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Tensile: Pulls an object apart
Compressive: Forces down on the object Shear: Tend to slide the top of an object over the bottom |
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What is creep?
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Any kind of material that has a dimensional change over time because of a constant load.
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What are the 3 stages of fatigue?
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Initiation, crack, rupture
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What is galvanic cell?
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Rusts because of 2 different metals
(the physical coupling of two different metals (like a battery) which causes the least noble of the metals to corrode at an accelerated rate) |
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What does soluble mean?
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Able to dissolve or make into a liquid
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What does sorption mean?
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Uptake of fluids or substances by a material
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What is a liner?
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Thin layer that seals the dentin on the floor and walls of the cavity.
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What are the purposes of intermediate materials, such as a liner and base?
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1. Seals dentin tubules
2. Reduces microleakage 3. Enhances retention 4. Stimulates the pulp 5. Reduces thermal shock |
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A base is not thicker than ____?
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1 mm
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What are some examples of bases?
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Glass Ionomer- gives out FL
Dycal: Calcium Hydroxide |
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Advantages of Alginate
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*easy to mis\x and manipulate
*Min. equipment required *flexible *low cost *accurate |
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Disadvantages of Alginate
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*doesnt transfer surface detail
*needs quick pour up *dries out really fast |
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Macrofill Composites
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*self-cured composite
*likes to stain |
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Microfill Composites
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*Very smooth
*doesnt last long |
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B-hemihydrate
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Plaster
*Large, irregular shaped crystal particles. |
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A-hemihydrate
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Stone
*small regular shaped crystals |
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Retarder
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Slows down the process
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Accelerators
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Speed up the process
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What is a die?
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a positive replica of a structure on which a wax restoration is prepared.
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If one adds MORE water than is specified to the mixture of plaster and stone, what will be the effect on the setting time?
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Increasing the amount of water ensures that fewer gypsum crystals will be formed per unit volume of the mix. This INCREASES the setting time by prolonging the time required for the crystals to grow enough to impinge on one another and produce strength.
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If one adds LESS water than is specified to the mixture of plaster and stone, what will be the effect on the setting time?
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reducing the water-to-powder ratio causes QUICKENING of the setting reaction by increasing the number of crystals per unit of volume.
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What is the normal setting time for plaster and stone?
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10 to 15 minutes
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When mixed with water, plaster or stone forms what?
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Gypsum
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Chemically, what is gypsum known as?
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Calcium sulfate dihydrate
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T/F: Plaster and stone differ in color.
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False: Plaster and stone are both white in color
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Which particles are more irregularly shaped, plaster or stone particles?
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Plaster particles; which means they have greater surface area and require more water for complete wetting during mixing
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If you compared a Low Copper Amalgam and a High Copper Amalgam, which mixture has a lower amount of Mercury used?
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High Copper amalgam
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This abrasive material is produced from volcanoes and is used in the laboratory to polish acrylics, and it is added to prophylactic pastes to polish teeth.
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Pumice
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What type of dental implant can only be used in the mandible?
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Transosteal because it is placed up through the bone
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When implants are immobile and you tap on the implant with an instrument what noise will it make?
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a solid ring
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Signs of problems with implants
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-radiolucency around the implant on an x-ray
-mobility -persistent pain or discomfort |
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With implants it is common for the bony ridge to resorb an average of _____ mm or so around titanium implants within the 1st year.
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1.5 mm
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The clinician checks the stability of an implant in a patient 6 months after placement. When tapping the instrument, a quiet "thud" is heard, causing you to predict the implant:
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Will demonstrate a radiolucency around a portion of its surface when filmed, and will show mobility when pushed or pulled with the fingers.
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What is osseointegration?
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the process by which new bone forms at the surface of an endosseous implant, creating a strong adhesion to stabilize it within the tissue. (stabilization of an implant by the formation of new bone in intimate contact)
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Why do we use precious metals in dentistry?
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They are resistant to corrosion and tarnish
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What is the lost wax technique?
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The process by which metallic dental castings are made; a wax pattern of a restoration is invested in a mold and then burned out to leave a space; a molten metal is then thrust into the mold to fill the space and produce a metallic restoration on cooling
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Is an impression a negative or positive replica?
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negative replica
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When a die material is poured into an impression is it a positive or negative replica?
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positive replica
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Is the MORE noble material known as the cathode or anode?
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Cathode
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Is the LESS noble material known as the cathode or anode?
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Anode; undergoes accelerated corrosion
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What is Inlay?
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a restoration within the cusps of the crown
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What is Onlay?
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a restoration that includes one or more cusps
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Good wetting occurs at an angle of ______.
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below 90 degrees
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What base do you use when pulp exposure is expected?
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Calcium Hydroxide (Dycal)
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In its unrefined state gypsum is ________, converted into a powdered _________.
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-dihydrate form of calcium sulfate
-hemihydrate |
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Which material has poor dimensional stability?
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Condensation silicones
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What material has best tear strength?
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polysulfide
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What is the most accurate material available?
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additional silicone
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What material is known for it's rigidity?
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Polyether
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What is the most common area for a mandibular denture to fracture?
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Midline
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Do hot and cold temperatures transfer well through a denture base?
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No-a denture insulates well
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Nickel allergy falls higher in what portion of the population base?
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Women
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Are there are any restrictions imposed on the use of nickel in dental restorations?
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No
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Glass ionomers suffer from a higher incidence of fractures and where when used on what surfaces?
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occlucal
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