DHS: Dental Materials

Amalgam

Amalgam

Alloy of Mercury = Silver: Sn Copper: Cu Tin Zinc: Zn

What metal in amalgam is a base metal and highly susceptible to corrosion in the mouth?

Silver

Why is copper added to amalgam?

Reduce rate of corrosion in amalgam To make it last longer

Tofflemire/Matrix Band Retainer

To maintain stability of matrix band during condensation of restorative material for class II preparation

Wedge with Tofflemire used to

Create a tight contact and prevent an over hang

In order to detect an overhang, visible on an xray, which in instrument in your cassette would you pick up?

Explorer (Shepards hook)

Bonding agent is used to establish

micro-mechanical retention with tooth structure.

Phosphoric acid etch is used to

create a roughened tooth structure in order to increase surface area for micro-mechanical retention.

Enamel is ______________ mineralized and is the ___________________ tissue in the body.

96%, hardest

Phosphoric acid etch is used for __________ secs and ______________ enamel.

15-20, demineralize.

When enamel is etched is appears...

Frosty!

What happens if we get etch on the dentin?

Destroy smear layer and dentinal tubules are now open.

If dentinal tubules are open, what happens?

Pain

Light cure products work by

Photo-initiators and cause chem reaction to polymerize.

2 reasons for bonding failures

-Salivary contamination -Oil contamination (from prophy paste)

Number one cause for bonding failure is....

Salivary contamination

Rubber dam is used to

isolate the restorative field from the rest of the mouth.

Sealants are

barriers that protect occlusal surface from bacterial assault.

What is the best way to prep an occlusal surface for sealant placement?

Prophy jet or Cavi jet

Steps for sealant placement

1. Pumice/ prophy jet - Rinse isolate dry

2. Etch - rinse dry

3. Apply/ wick off excess

4. Polymerize (light cure)

5. Check retention/ occlusion

Composites are

Esthetic restoration made with a bonding agent = micro- mechanical retention with tooth structure

Composites are made from

silicates, quartz, glass = filled with tooth colored particles

What are added to composites so they appear radiolucent on xrays?

Silicates, quartz, glass

Barium and Strontium are added to composite resins for....

Radiopacity

Handling characteristics, classification and clinical application of composites are dependent on...

Filler particle size.

Microfill particles in composite = Midifill particles in composite = Nanofill = Blended all =

Nerds + Jelly beans + Sugar = Nanofilled micro-hybrid

Liners are used

Seal dentinal tubules or Seal and medicate the pulp

Calcium hydroxide is used to

Seal dentinal tubules medicate the exposed pulp horn Stimulate odontoblast to stimulate reparative dentin = NO RCT

Zinc Oxide Eugenol (ZOE)

Liner Oil of clove = soothing to pulp Cannot use under a composite

Resin-modified glass ionomer

Most popular liner used today bonding agent that has glass ionomer powder and releases Fluoride

Bases

Insulate and protect the pulp

Cements are

nonconductive and have compressive strength

Liner only when

small dentinals are exposed = small cavity

Base & Liner is used when

large cavity and pulp is exposed = pink no bleeding to insulate & reduce sensitivity

Zinc phosphate is a _______________ ______________.

exothermic cement = generates heat. Mixed on glass slab

Which of the following cements generates heat when mixed? A: Zinc Eugenol B: ZInc phosphate

B: Zinc phosphate

Polycarboxylate cement must be mixed with.....

polyacrylic acid liquid

Glass Ionomer cement

-Binds to dentin -Releases fluoride -Expands/contracts ike tooth structure -Can be used as a class V restorative material

Resin cements

USed for esthetic situations

Resin based glass ionomer

Hybrid cement = viscosity

Zinc- Oxide Eugenol cement is used for

Temporary crowns, soothes pulps

How do you clean zinc-oxide eugenol?

Orange solvant

Elastomeric

Material with elastic properties = think elastoman = flexible

2 Elastomeric materials

Water soluble = hydrophilic (loves H2O) Water insoluble = hydrophobic (hates H2O)

Water soluble elastomerics

Hydrocolloids = Reversible (agar) Irreversible (alginate)

Agar undergoes a reversible reaction is because undergoes a

physical reaction.

Solidification by cold is called..

gelation

Hydrocolloids Irreversible (alginate) undergoes change by a _______________ reaction.

Chemical

Cold water _____________ sets alginate and warm water _______________ alginate set time.

slows, accelerates

Syneresis means (alginate)

Loss of a solvent by a solute = to shrink = losing water to atmosphere

Imbibition means (alginate)

Absorption of a solvent = to swell = taking on water

Why do we aerate the alginate powder?

Because it is a fine powder

Elastomeric insoluble

polyether rubber

Which of the hydrophobic impression materials distorts when left in water?

Polyether rubber

Gypsum

calcium sulfate dihydrate = 2 molecules of water

How do we get alpha or beta calcium sulfate hemihydrate?

from calcium sulfate DIHYDRATE = heated and water extracted

To use gypsum we need to ...

add the water back = expands as it sets!

The more water we add to gypsum, the ______________ _________________.

greater expansion = lower compressive strength.

Beta calcium sulfate hemihydrate gypsum is

Plaster = big expansion, particles further apart = takes a lot of water and is lower compressive strength

Alpha calcium sulfate hemihydrate gypsum is

Stone = less water = less expansion and higher strength.

Put in order the weaker to stronger gypsum products. Alpha STONE Beta PLASTER Alpha DIE STONE

Beta Plaster Alpha Stone Alpha Die Stone *** Think A id better than B ****

Diestone contains

a chemical additive to make it stronger

Diestone is used for

working models by lab techs

What 2 agents can modify gypsum products?

Borax = slows it down (think burro = slow donkey) Potassium sulfate = speed up (think eating a banana will make you fast)

A model base should be trimmed

perpendicular to the midline

What is inlay wax?

Wax used by the lab tech to create the waxed patterns on models

Waxes are

modified paraffins

Utility was is used for..

cushion ortho brackets and appliances modify an impression tray to cushion edges

Casting alloys

used to make inlays, onlays, creons, bridges

Inlays fit

"in the tooth, in the cusp"

Onlays fit

cover the cusps

Casting alloys are categorized by

alloy composition = precious or non-precious metals

Precious alloys are

noble metal = last a long time and resistant to tarnish and corrosion. Gold, platinum & palladium

Non-precious alloys are

Base metals = tarnish & corrosion Nickel: 50% females have Nickel allergy

Do not treatment plan for a PFM for a patient that has a metal allergy because

gingival tissue will never heal due to allergy

How do we polish gold in the mouth?

Tin oxide = okay in mouth

Why cant we polish gold in the mouth with rouge?

Because it is toxic

T or F: Gold foil will always look like gold

True and will always be at the gumline or front of the mouth = have to hammer = 1st premolar to premolar.

Implants are used because

they are biocompatible alloy of titanium

Endosteal means

within bone

Failure of implants is due to

No integration Inadequate bone Peri-implantitis (inflm around implant)

Contraindications for implants

Inadequate bone Periodontal disease Uncontrolled diabetes Smoking Infection Bisphosphonates

Bisphosphonates

increase bone density, but decrease vascularity = decrease healing potential.

Can we use an electric toothbrush and air polisher on an implant crown?

YES

Do we scale implant with a metal instrument?

No, never

Pyrophosphates are

tarter control toothpastes = leading cause of dentinal sensitivity

Triclosan

ACTIVE ingredient in gum care toothpaste = antiseptic

Potassium nitrate Sodium Citrate Strontium Chloride are all ingredients found in what toothpaste?

Active ingredient in Antihypersensitivity Toothpastes

Hydrogen peroxide Carbamide bicarbonate are active ingredients in which toothpastes?

Home bleaching pastes

Sodium bicarbonate is the active ingredient in..

denture cleansers

Thermoplastic polymer is used for

mouthguard fabrication

Polymethylmethacrylate & Bis-acrylic resins are used for?

Temporary crown restorations

Which dental tissue most look like enamel?

Porcelain

Galvanism is

Generation of electrical current when dissimilar metals are in an acidic environment

Irreversible hydrocolloid

alginate

Tensile

capable of being stretched

Ductility

Ability of material to undergo a change in shape of from without breaking

Malleability

materials capacity to be shaped by force or pressure

Compressive strength

the force a material can withstand before breaking

Final mercury content on high copper amalgam restorations is

50 % or less