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Dental Materials > Test 2 > Flashcards

Test 2 Flashcards

1
Q

Review self-cure

A

Self cured (also known as chemically cured) is when two pastes mix and a chemical reaction occurs

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2
Q

Review light-cure

A

Light cured means it is activated with (blue) light; this is the most common cure for resins

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3
Q

Review dual-cure

A

Dual cured means it uses both chemical and light, with the light beginning the reaction and chemical reaction occurring where the light can’t reach

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4
Q

Review glass ionomers

A

Self or light cured fluoride releasing materials. Can be used as luting cements, liners and bases, and restorative materials, and they are very wear resistant. They cannot be polished. They are hand mixed as a powder and liquid and can seal the root surface better than composite resin.

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5
Q

Review resin matrix

A

Organic resin matrix is a thick liquid made up of two or more types of organic molecules called oligomers. The most commonly used resin for the matrix site is bisphenol-A-glycidyl dimethacrylate (bis-GMA)

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6
Q

Review filler particles

A

Filler particles are added to organic resins to make them stronger and more wear resistant. Inorganic particles are used such as quartz, silica, and glass. The smaller the particles the smoother the surface will be. The higher the filler content, the stronger and more wear resistant the restoration will be, and it will shrink less when polymerized.

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7
Q

Review coupling agents

A

The coupling agent saline is used to provide a stronger bond between the inorganic fillers and the resin matrix.

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8
Q

What are the classifications of composite by filler size?

A

Macrofilled, microfilled, and hybrids, microhybrids, nanohybrids, and nanocomposites

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9
Q

What are macrofilled composites?

A

Macrofilled composites contain the largest of the filler particles. They have great strength but a dull, rough surface, and they stain easily.

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10
Q

What are microfilled composites?

A

Microfilled composites contain much smaller particles, making them weaker but they do not stain easily and can be polished to smooth.

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11
Q

What are hybrid composites?

A

Hybrids are a combination of macro and micro filled

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12
Q

What are microhybrid composites?

A

A combination of smaller particles and micro fine particles

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13
Q

What are nanohybrid composites?

A

Nanohybrids are microhybrids with nanosized particles (they are also called universal composites because they are both strong and esthetic).

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14
Q

What are nanocomposites?

A

Nanocomposites have filler particles that are about a thousand times smaller than conventional fillers.

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15
Q

How are composite resins classified?

A

Self cured and light cured

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16
Q

What is the purpose of the saline coupling agent

A

It reacts with the surface of the inorganic filler and of the organic matrix to allow the two to better adhere together, minimizing loss of filler particles and reducing wear.

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17
Q

Review polymerization and shrinkage

A

The chemical reaction that occurs when low molecular weight molecules called monomers join to form long-chain, high molecular weight molecules called polymers. Chemicals that cause polymerization to occur are initiators and activators. Shrinkage occurs when composite resin is polymerized.

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18
Q

What is the oxygen inhibited layer?

A

Also called air-inhibited layer, it is a layer of unset resin on the surface of a polymerized bonding resin that is prevented from curing by contact with oxygen in the air. Once composite resin is placed over the bonding resin it will exclude the air and cure when the composite cured, helping facilitate the bond between the two. Oftentimes this layer is wiped off.

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19
Q

What is the optimum levels of fluoride in community drinking water

A

0.7mg of fluoride per litre

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20
Q

Review desensitizing agents

A

Used to reduce or eliminate sensitivity. They can be occluded (plugged) into open tubules to stop pressure on nerve endings, or they can desensitize the nerve endings with potassium nitrate.

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21
Q

What is fluorosis and how does it occur?

A

It is caused by too much fluoride, resulting in an enamel condition.

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22
Q

Review possible causes of tooth sensitivity.

A

Exposed dental tubules in the oral cavity resulting in pain when fluid in the tubules move (known as hydrodynamic theory), temperature (cold), sugar, acid, exposed root structure.

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23
Q

Review indications for sealants.

A

Steep cuspal inclines, deep sticky fissures.

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24
Q

Review the steps of sealant placement. (i.e: tooth prep, etch, sealant etc.) What should an etched surface look like? What type of etch is used?

A

Clean surface with pumice
Etch enamel with 37% phosphoric acid (should be rough)
Rinse with water
Dry the enamel
Bonding (optional)
Place sealant
Cure
Wipe cured surface with gauze or a cotton roll

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25
Q

Review systemic versus topical fluoride.

A

Topical (gels foams, varnish), systemic (water, pills)

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26
Q

Review the use of gels and foams as a topical fluoride

A

Gels and foams are applied in disposable trays for 4 minutes, used to be very popular but now is less so, although they are still commonly used.

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27
Q

Review the use of varnish as a topical fluoride

A

Varnish is now the most common form of fluoride used, they are applied directly onto the tooth surfaces and last longer than other products. Vanish is useful for direct application to early dental caries that can re-mineralize and can supply a high concentration of fluoride to the porous de-mineralized enamel

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28
Q

Review pros and cons of whitening

A

The main pro of tooth whitening is that the client feels happy with their teeth. Side effects can include sensitivity (usually short term), inflammation, and muscle soreness.

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29
Q

What are some potential side effects that may occur from bleaching?

A

Sensitivity (usually short term), inflammation, and muscle soreness.

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30
Q

What types of stains are the most difficult to remove with vital tooth whitening? Which are the easiest?

A

Extrinsic stains are the easiest to remove, and can sometimes even be removed by the client, as long as they have not penetrated enamel. Intrinsic stains are internal. Yellow stains are easier to remove than blue.

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31
Q

How does tooth whitening occur?

A

Peroxide or other materials pass through the space in enamel, reaches the dentin, and releases oxygen free radicals, which oxidize the stains and lightens the color of dentin.

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32
Q

Review stain types and how they are removed.

A

Extrinsic can be removed with scaling, coronol polish or air polish. Intrinsic stains require internal whitening.

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33
Q

Review the difference between home whitening, in-office and OTC. Is one more effective than another is? What are the active ingredients?

A

In office, patient has protection of their tissues and process can be much faster due to higher intensity. At home it can take multiple months. In office a gel of 35 or 45% carbamide peroxide is used, or a power whitener activated by light. At home, the chemical is either 10-45% carbamide peroxide or 6-15% hydrogen peroxide.

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34
Q

Review hydrogen peroxide and carbamide peroxide. What percentages are they available in and percentages of each?

A

Hydrogen peroxide can be purchased in liquids, gels, or varnish in concentrations from 5%-40%. Carbamide peroxide (popular for home whitening) is purchased in liquids or ells from 10%-35%, with some gels 44%.

35
Q

Review non-vital whitening

A

Non-vital teeth no longer have a living pulp and ceases to give response to electrical stimuli or temperature change. Whitening on non-vital teeth requires removing the restoration from the endodontic access cavity and whitening internally.

36
Q

Know what the first layer of porcelain that is applied to the metal during fabrication of PFM restoration is.

A

The first layer of porcelain is an opaque porcelain, such as Zirconia, because it is very strong.

37
Q

Review CAD/CAM. What are the advantages?

A

Computer aided designing and machining allows 3d image of tooth prep from all angles, allowing modification of the prep and no impression needed.

38
Q

Know the main advantages of all-ceramic crowns over PFM/PBM crowns and disadvantages.

A

Primary advantage is esthetics, and they are also biocompatible, stain resistant, and wear resistant, but they are brittle and difficult to repair and polish.

39
Q

Where are all-ceramic Porcelains usually placed and why?

A

Porcelains – most esthetic but weakest / used more for anterior tooth / used to make porcelain veneer / serve well once they are bonded to the enamel and used in low-stress areas / used to veneer cores made from stronger but less esthetic materials such as alumina, zirconia
Leucite-reinforced ceramics – mixture has more than tripled their fracture resistance / work well for inlays, onlays, thicker veneer, anterior crowns / not strong enough for posterior crowns
Lithium disilicate – high strength, good marginal integrity, biocompatibility, high translucency = good for esthetic / used anterior or posterior
Alumina and Zirconia – non glass ceramic = very strong / some what opaque – not good for anterior
Alumina – has very high flexural strength / show an increased risk of fracture when used for molar crowns, used for anterior and premolar
Zirconia – the strongest ceramic materials / highest flexural strength
Porcelain-metal restorations – most commonly used restoration in fixed (crown and bridge) prosthodontics / forming a durable bond

40
Q

Review uses for all-ceramic restorations.

A

Veneers, onlays, anterior crowns, fixed prosthodontists

41
Q

Review the terms sintering, clip casting and heat-pressing.

A

Sintering- fusion of ceramic particles at their boarders by heating them to the point they begin to melt.
Slip-casting – ceramic powder is mixed into a water based liquid to form a slip, which is pressed into a form and baked at high temps.
Heat-pressing – Uses the lost wax technique to press molten ceramic material into a mold at a high temperature.

42
Q

Review what amalgam should look like when it is under-triturated, over-triturated, and properly triturated.

A

Under-triturated will look dry and crumbly, over-triturated will appear wet, and properly triturated will have a satin-like appearance.

43
Q

Review the steps for placing an amalgam restoration.

A

Using small increments it should be placed into an amalgam well and must overflow.

44
Q

Review the terms creep, trituration, amalgamation, tarnish and corrosion.

A

Creep- gradual change in shape of a restoration usually caused by compression from occlusion or adjacent teeth and can cause amalgam to bulge out of the cavity preparation.
Trituration- using the triturator, which is a mechanical device used to mix silver based alloy particles with mercury to produce amalgam (mixing together)
Amalgamation- reaction that occurs when silver-based alloy is mixed with mercury to form an amalgam.
Tarnish- oxidation affecting a thin layer of metal at its surface that does nit change the metal’s mechanical properties.
Corrosion- breakdown of a metal by chemical or electrochemical reaction with substances in the environment such as water or air. It negatively impacts the properties of amalgam.

45
Q

Review setting times of amalgam.

A

5.5-6 minutes

46
Q

Review contents of an amalgam filling.

A

Always made of predominantly silver, with some copper and tin and potentially some other metals. Silver is between 40-70%, with tin at 12-30%, copper of 13-30%, and mixed with mercury 42%-52% by weight.

47
Q

Know the difference between amalgams used today versus predecessors.

A

Modern dental alloys are high in copper content today compared to their predecessors.

48
Q

What is an alloy

A

A solid compound made up of two or more elements of which at least one is a metal.

49
Q

Know the three major categories of alloys and their noble metal content

A

High noble alloys contain at least 60% noble elements (gold, platinum, palladium), and 40% of that 60% must be gold.
Noble alloys contain at least 25% noble elements with no gold requirement.
Base mentals consist of less than 25% noble elements.

50
Q

Know the difference between non-precious (noble metals) and precious metal (base metal) and examples of each

A

Noble metals are gold, platinum, and palladium, while precious metals are copper, nickel, silver, zinc, tin, and titanium.

51
Q

What metals are used to increase the hardness of high-noble metals?

A

Copper, silver, and gallium.

52
Q

Know which base metal has the highest incidence of allergic response.

A

Nickel

53
Q

Review wrought wire and its advantages.

A

Wrought wire has improved ductility and malleability, and can be formed after the metal is cast.

54
Q

Know what the primary use for dental posts are for.

A

To retain the core buildup over which the final restoration (crown) is placed.

55
Q

Know the success rate of implants

A

High for endosseous implants, 90% in maxilla and 95% in mandible.

56
Q

Know the three different implants used in dentistry and which is the most common.

A

The most common is endosseous, which is where the implant is surgically placed into bone. The other 2 implants are transosteal (placed under chin) and subperiosteal (surgical incision on bony ridge)

57
Q

Know the most commonly used metal for implants.

A

Titanium

58
Q

Know what a surgical stent is and what its purpose is.

A

An appliance used for radiographic evaluation of hight and width of the available bone during treatment planning for implant placement or during surgical procedures to provide site for optimum implant placement.

59
Q

Define osseointegration.

A

When a soft tissue flap is used to cover the extraction site until bone fills in and integrates with the fixture.

60
Q

Review the different surgical procedure and how they differ (two-stage, one-stage, & immediate placement).

A

Two-stage: the first stage involves exposing the bone with a surgical flap, a hole is drilled in the bone, and an implant is put into the bone, a screw is added, and the surgical flap is closed. At the second stage, roughly 3 months later, the screw cover is removed and a healing abutment is added.
One-stage: Same as two-stage but the top of fixture projects through the soft tissue at the time of surgery and a healing abutment is placed, The soft tissue is sutured around it rather than covering it.
Immediate: When a tooth is extracted the implant can be placed directly into the new socket at the time.

61
Q

Review what type of instruments should be used when treating a patient with an implant.

A

Titanium instruments should be used, and plastic can be as well.

62
Q

What causes failures of implants?

A

Early failure is usually due to failure of the bone to integrate with the implant, while delayed failure can be caused by bacterial infection or overloading resulting in a loss of supporting bone.

63
Q

Review the 4 graft types.

A

Autografts are harvested from the patient’s own body.
Allografts are harvested from human bodies upon death (cadaver bone)
Xenografts are harvested from animals, usually cows.
Alloplasts are synthetic material

64
Q

Why is titanium used for implants?

A

Titanium is used for implants because it is biologically compatible with oral tissues and are lightweight and corrosion resistant, allowing bone to grow around and fuse with the implant.

65
Q

Why is it important to finish, polish and clean tooth structures and restorative materials?

A

It improves aesthetic, improves tissue health, and increases longevity of the restorative material. Routine polishing is not recommended.

66
Q

Review factors affecting abrasion.

A

Rate of abrasion is determined by the abrasive being used and the surface being abrated.
Abrasiveness of particles is determined by size, irregularity, and hardness of the particles: Size, hardness, numbers, speed, and pressure.

67
Q

Review benefits of properly finishing and polishing restorations.

A

Decreased biofilm retention, resistance to tarnish/corrosion, increased longevity of the restoration, decreased attrition of natural tooth surfaces during chewing, improves aesthetics, improved health of surrounding tissues.

68
Q

How are dental abrasives supplied?

A

Two-body abrasives, three body abrasives, and microparticle abrasives.

69
Q

How do commercially prepared dentifrice differ from prophylaxis paste? (HINT: abrasiveness)

A

It is 20 times more abrasive to dentin and 10 times more abrasive to enamel than commercially prepared dentifrice.

70
Q

Review philosophy of selective polishing.

A

It should only be preformed after the needs of the individual are evaluated and considered.

71
Q

Define polymer.

A

Long-chain, high molecular weight molecule produced by chemically linking many low molecular weight monomer molecules.

72
Q

Review homecare procedures for dentures.

A

Clean every day – 2x if possible
Hold over a towel or sink filled with water (this prevents fracture if the denture gets dropped.
Clean with denture brush
Use non-abrasive denture cleaning paste
Remove and rinse after eat – food will get under
Don’t use hot water – may warp
Rinse mouth to remove debris
Remove dentures at bed – or at least 4 hours/day
Store in water when not wearing.

73
Q

What should dentures be soaked in? What should be avoided and why?

A

Dentures can be soaked in 1:1 vinegar and water, 1:10 bleach and water, or denture cleaning solution. They cannot be soaked in alcohol because they will dry out.

74
Q

Review short-term and long-term soft liners and hard relining materials. Know why relines are necessary sometimes.

A

Long term liners are made of silicone rubber or acrylics and are for patients with chronic denture pain. Short term liners are tissue conditioners or tissue liners placed chairside to allow tissues to heal short term. Reliners can fix looseness due to gum shrinkage, repair, act as a tissue conditioner to improve health of the tissue before a hard reline done, serve as a functional impression for a hard reline, and prolong the life of the denture as an alternative to making a new one.

75
Q

Know the difference between relining and rebasing.

A

Relining is used to allow the denture to fit again, while rebasing is replacing the base but not the teeth.

76
Q

Review chairside reline procedure.

A

Chemical-cured acrylic resin is used (Polymer powder & liquid monomer)
Acrylic bur used to remove thin layer of tissue-bearing surface
Resin applied to denture and placed in mouth
Reline material is taking impression of the tissues

77
Q

Review what denture teeth are made of and the pros and cons for each.

A

Acrylic resin teeth – tough & chemically bonded to the acrylic base of denture. They do not wear down the occluding teeth, but they are soft and wear more readily than porcelain.
Composite resin teeth – have a more natural appearance & translucency, having better aesthetics.
Porcelain teeth – brittle, hard & highly resistant to wear. They are prone to fracture and have good esthetics only until the surface wears off. And they are very abrasive, but they can chew hard.

78
Q

Review in-office care of dentures.

A

Can soak in denture cleaning solution to remove calculus
Place in zippered bag containing solution
Place into ultrasonic
Can also carefully scale off and then polish with flour pumice

79
Q

Review uses for Stainless Steel Crowns (SSC). What is the most common use?

A

Stainless steal crowns are the most durable of the performed crowns, providing provision coverage lasting months and even years. Their primary advantage is their malleability with provides for good contact, occlusion, and marginal integrity.
Preformed crowns have more convenience. They are already premade and saves time.
Aluminum shell crowns are used for provisional coverage of posterior teeth, lines with acrylics or composites and cemented with temporary cement. Can last for several weeks.
Stainless steal crowns are most commonly used to restore primary teeth

80
Q

How long are provisional restorations used for approximately?

A

Generally 2 weeks to a month

81
Q

Review the functions of a provisional crown (anterior and posterior).

A

Aluminum shell crowns are good as a posterior provisional crown material, and for anteriors it’s polycarbonate and celluloid crowns. Esthetics and comparability with acrylic resins allows for further customization for fit and margins

82
Q

Review what negative affects can happen to during the polymerization of chemical-cured acrylic.

A

Heat caused by polymerization can damage pulp or burn soft tissue

83
Q

Review the primary advantages of the preformed polycarbonate provisional crowns

A

They are convenient; they save time and money and are good for emergency situation.

84
Q

What is an advantage of using image-guided implant planning?

A

You can place the implant without layering a flap, leading to less postoperative discomfort and faster healing. Fewer perforations of bone by a misaligned drill. Improved prosthetic outcomes of treatment and enhanced esthetics because of better implant placement. Increased survival rates for the implants.

Dental Materials (2 decks)

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