DH Boards; Dental Materials

The chemical attraction between unlike molecules? (tape)

Adhesion

The chemical attraction between like molecules? (glue)

Cohesion

An index which indicates how one material reacts to temperature extremes in relation to another?

Coefficient of Thermal Expansion

The force at which a material breaks under pressure?

Compressive strength

Slow dimensional change caused by compression?

Creep

The ability to undergo change of form without breaking? (like the wire twistie on bread)

Ductility

A materials ability to recover its initial shape after undergoing a force?

Elasticity

An electrical current generated by dissimilar metals in an acidic environment?

Galvanism

The process of gelling? (solidification by cold) like jello in fridge

Gelation

The volumetric weight of one cubic centimeter of milliliter of water?

Gram

Absorption of a solvent by a gel?

Imbibition

A material's capacity to be shaped by force or pressure? (like play-dough)

Malleability

Passage of oral fluids/bacteria into and out of tooth structure due to marginal (restorative) seal?

Microleakage or Percolation

the linking, branching, or cross-linking of smaller molecules?

Polymerization

the force at which a material CANNOT return to its original shape?

Proportional limit

Contraction of a gel due to the loss of a solved? (ex. dried alginate)

Syneresis

The force needed to stretch a material to the point of fracture?

Tensile Strength

Resistance to flow?

Viscosity
Low viscosity-->water
high viscosity--> peanut butter

If you change a material's components, you change its properties?

Truisim

What 5 things make up amalgam?

-mercury
-silver
-copper
-tin
-zinc

3 desirable features of amalgam?

durable
similar compressive strength to enamel
relatively inexpensive

Undesirable features of amalgan? x7

-unattractive
*high thermal conductivity
*Dimensionally unstable (creep)
*delayed expansion if contaminated by saliva
*Requires tooth support
*Fracturable by excessive occlusion
*Susceptible to galvanism when new

When Polishing amalgams; what is final polish?

Tin oxide

How do you polish amalgam?

light touch with water and short burst to avoiding heat that will damage the odontoblasts

How do hygienist remove an overhang? because apparently boards thinks we can!

With a SCALER, not a curett

What establishes a mechanical retention with enamel or dentin and Dental Resins?

Phosphoric Acid

What does phosphoric acid increase?

surface area

What does BIS-GMA stand for?

bisphenol a-glycidyl methacrylate

Do sealant material have a low or high viscosity?

Low

Do composite have a low or high viscosity?

High

What are the 3 more common filler particles in composite?

Silicates
Quartz
Glass

What is added to composite for radiopacity?

Barium or stontium

What Resin-fill size is popular due to its high polishability and ease of handling, but requires tooth support?

MICROfills

Which resin-fill size is popular due to its COMBINED strength and beauty?

HYBRIDS

What resin-fill size increases surface area and, therefore, bond strength?

NANOFILLS

By adding what to composite increases polishability?

NANOFILLS

Is light cured (unmixed) or self cure (mixed) more porous?

Self cured is more porous, because when mixing it adds air, and that is bad

What do you polish composites with?

Tin oxide or diamond polishing paster

What is used to seal dentin or medicate the dental pulp?

Liners

What are 4 liners?

Varnish
Calcium Hydroxide
Zinc-oxide/eugenol
Resin-modified glass ionomer

What liner is fluoride releasing?

Glass-ionomer

What liner is CX with composites and why?

Zinc-oxide/eugenol because of the oil (IRM)

What Liner is placed over pulpal exposure to stimulate reparative dentin?

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CALCIUM HYDROXIDE
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What is used to proved thermal insulation or mechanical protection for the dental pulp (iusulate/protect like a Blanket)

Base=blanket to insulate, keep warm

Why are cements included as bases?

because cements are poor thermal conductors and have adequate compressive strength

What cement causes an EXOthermic reaction when mixing, a cool glass slab is needed, and uses a mechanical interlock between tooth and casting?

ZINC phosphate cement

What cement is a powder mixed with poly acrylic acid and has a high chemical affinity for enamel?

Polycarboxylate cement

What cement releases fluoride, binds to dentin, and can be used and a class V restoration?

Glass ionomer cement

What cement is tooth colored to use with esthetic restorations like veneers and onlays and ortho brackets, and pre-fab. post?

REsin cements

What cement is a resin modified glass ionomer and therfore releases fluoride and can be esthetic?

HYBRID (rely-X)

What cement is commonly used for temporary cementation?

Zinc-oxide/eugenol cement

What is uded to clean ZOE contaminated instruments?

Orange solvent, not alcohol

What are the 2 types of impression material?

Rigid and Flexible

What are the 2 types of flexible impression materials?

Aqueous and non-aqueous

What are the 3 stupid types of RIGID (inelastic) impression materials?

plaster, compound, and zinc-oxide/eugenol

What are the 2 types of Aqueous impression materials?

Reversible hydorcolloid or non-reversible hydrocolloid

What is another name for Reversible hydo-colloid?>

AGAR

What type of reaction does Agar undergo?

Physical, gelation; when cold id solidifies

Agar is susceptible to imbibition and syneresis, meaning what?

syneresis...smaller when loses water
Imbibition...larger with absorbing more water

What is another name for Irreversible hydrocolloid?

Alginate

What typer of reaction does alginate undergo?

Chemical reaction

Is alginate temperature dependant?

No; but setting time can be delayed/accelerated by it

Non-aqueous impression material is water-insoluble or ?

hydrophobic

What are 4 non-aqueous impression materials?

Polysulfide rubber
polyether rubber-unstable in moisture
Silicone rubber
Polyvinylsiloxane***crown prep impression

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BOARD
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Mixing times for impressions materials vary according to manufactures directions

Does Gypson shrink or expand as it sets?

Expands

What is Gypsum made out of?

Mineral, Calcium Sulfate di-hydrate

the more water needed in gypsum; the greater the setting expansion and lower the what?

Lower the compressive strength

Alpha/Beta? which one is superior?

Alpha is better, A's are better than B's, but C's get degrees!

What can be added to accelerate gypsum set time?

Potassium sulfate; potassium in banana's make you fast)

What can be added to slow the set of gypsum?

Borax; (borax is boring and slow)

Air incorporated into gypsum mix will result in what?

surface voids (bubbles/holes)

Model base is trimmed __________ to midline between central incisors.

Perpendicular

What is Inlay and casting wax best used for?

Cast restorative patterns

What is base-plate wax best used for?

removable prosthetic procedures

What is bite registration wax used for?

obtain occlusal records

What is boxing wax used for?

Used in pouring models

What is sticky wax used for?

attach models (hard when cool, sticky when heated) like when the wire retainer comes back from the lab attached to the model :)

B
What is utility wax used for?

modify the shape of impression trays and cushion brackets

For the greatest demensional accuracy, what should be done with wax?

invest wax pattern soon, avoid heat

How are casting alloys classified as?

Precious or Nonprecious

What 3 metals are used in dentistry and are Precious?

Gold
Platinum
Palladium

What 5 metals are Non-Precious used in dentistry?

Silver
copper
Nickel
Tin
Zinc

Which casting alloys tarnish and corrode?

Non-Precious

Intraorally, what can gold be polished with?

Tin Oxide

Extra-orally, what can gold be polished with?

Rouge; its a poison, so can't be used intra-orally

Pure gold is 24K (100%); how much is that in FINE?

1000 Fine

What is 18K in Fine?

18/24 = 3/4, 3/4 of 1000F is 750 Fine

What can opposing porcelain restorations cause?

Occlusal wear; use gold

What is the leading cause of Implant failure?

Mobility

What are 4 condra-indications for implant placement?

Inadequate bone
uncontrolled perio
smoking
Infection

Is an electric toothbrush contraindicated with implants?

NO

Can a air-powder polisher be used with implants?

Yes

What is the active ingredient in tarter control tooth-paste?

Pyrophosphate

What is the leading cause of dentinal hypersensitivity?

Pyrophosphate found in tarter control toothpaste

What is the active ingredient in gum care toothpaste?

Triclosan (antimicrobial agent)

What are 3 desensitizing ingredients in toothpaste?

Potassium nitrate
sodium citrate
strontium chloride

What are 2 desensitizing agents applied professionally?

Potassium oxalate and fluoride varnish

What are 2 active ingredients in vital bleach (home bleach)?

Carbomide peroxide and hydrogen peroxide

What does carbomide peroxide break down into?

hydrogen peroxide and urea