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Intro to Dentistry Materials > Dental Cements > Flashcards

Dental Cements Flashcards

1
Q

Define “luting”

A

to glue

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2
Q

When using cements as luting agents, materials are cemented together mostly via _____ ____

A

mechanical bonding

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3
Q

Requirements of luting agents

A
  • set in the mouth
  • Biocompatible
  • none soluble in oral fluids
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4
Q

Cements as luting agents provide ___ and ____

A

retention and sealing.

Purpose is to cement a restoration to the tooth. To reduce microleakage by filling in the gap between the restoration and the cavity wall

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5
Q

Format of luting agent cements

A

powder + liquid or paste

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6
Q

Physical properties of cement luting agents

A

good flow, SMALL AND LITTLE OR NO FILLER PARTICLE SIZE

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7
Q

What type of reaction cementra have typicaly been used to lute metal and ceramic crowns?

A

Acid-base reaction cements

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8
Q

Luting cements use the __ surface to ____ lock along the path of draw

A

Luting cements use the ROUGH surface to MECHANICALLY lock along the path of draw

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9
Q

Why is pulpal protection necessary?

A

Because when bacteria encounters the pulp, the immune system kicks in and sends more blood towards the affected area. However, since the pulp is contained within a strong chamber (enamel), there is no space for additional material/fluid. When inflammation occurs, pulpal tissue begins to die due to cramming.
In summary, when pulpal cells try to save themselves with inflammation response, they end up killing themselves.

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10
Q

Challenges surrounding the replacement of enamel or dentin

A
  1. chemical protection
  2. thermal and/or electrical protection
  3. mechanical protection
  4. pulpal medication
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11
Q

The flow of fluid is always from __ to ___ in the tooth

A

From PULP to CAVITY

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12
Q

Pressure within the pulp

A

Pressure is high (40 mmHg)

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13
Q

Why woud topical acid not go down into the pulp and cause damage?

A

Because the high pressure within the pulp (40mmHg) causes fluid to flow outwards towards the cavity. For this reason, fluid will not penetrate the pulp through the dentinal tubules

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14
Q

RDT stands for ___ ___ and requires additional protection when it is below ___

A

RDT stands for REMAINING DENTIN and it requires additional protection hen it is below 2mm

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15
Q

What causes sharp pain and sensitivity in the tooth?

A

fluid flow.
If something occurs to increase the fluid flow, osmoreceptors (due to osmotic pressure change) and mechanoreceptors (due to change in fluid pressure) send signals to the brain. IF TUBULES ARE BLOCKED, PAIN IS REDUCED

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16
Q

What effect does blocking dentinal tubules have on pain response?

A

reduced

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17
Q

Heat is added or extracted from the pulp by the _____ ____

A

microcirculation system

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18
Q

T/F: composites or glass ionomers are insulating materials

A

true

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19
Q

Chemical protection of the pulp comes from:

A

sealing the tubules

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20
Q

Biological protection of the pulp comes from:

A

pulpal medication

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21
Q

Role of sealers / varnishes/sealers

A

To form a coating on the tooth and seal all the cavity preparation.
ACT AS A BARRIER TO FLUID FLOW/LEAKAGE and protect pulp against TOXIC AGENTS in the filling materials

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22
Q

Role of bases

A

materials used to replace missing dentin and bulk build-up

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23
Q

Rank 3 basic cements from thinnest to thickest

A

varnish

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24
Q

T/F: cavity sealers provide thermal protection

A

false

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25
Q

should varnish be painted on dentin and enamel?

A

yes. Entire cavity wall including dentin and enamel

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26
Q

Varnish is ___ dissolved in ____

A

RESIN dissolved in SOLVENT

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27
Q

Under which restorative material can you NEVER use varnish? WHy?

A

Under adhesive/composites (prevents setting reaction) or glass ionomore (prevents F release).

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28
Q

varnishes create hydro____ thin films

A

HYDROPHOBIC

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29
Q

How are varnishes hardened?

A

By polymerization reaction by visible-light curing

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30
Q

Liners are placed between the ___ ___ and the ____

A

PULPAL WALL and the RESTORATION

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31
Q

___ have a therapeutic effect on the pulp

A

liners

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32
Q

bacteria typically live in ___(high or low?) pH

A

low

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33
Q

Format of liners

A

powder + liquid or paste

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34
Q

where are liners applied

A

Thin layer only on the dentin walls that face the pulp

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35
Q

Where can you NEVER place liners? why?

A

Never place liners on enamel because enamel is not alive. There are no particles to “take” the calcium

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36
Q

Liners have ___ strength and ___ solubility

A

LOW strength and HIGH solubility

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37
Q

Calcium hydrixide mix involves equal amounts of ___ and ___

A

CATALYST and BASE

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38
Q

How is calcium hydroxide cured?

A

silf-cures in 2-3 mins

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39
Q

Cover CaOH in ___

A

Glass ionomore

40
Q

How is GI cured?

A

light cure for 20 sec

41
Q

When should I use a base?

A

When RDT is less than 2mm

42
Q

The base replaces lost ___

A

dentin

43
Q

Purpose of bases:

A

Thermal, chemical and mechanical protection of the pulp. May

44
Q

Amalgams placed over ___ stiffness bases fracture more than those placed over ___ stiffness bases

A

Amalgams placed over LOW stiffness bases fracture more than those placed over HIGH stiffness bases

45
Q

ZOE, zinc phosphate, polycarboxylate and GI are examples of ___

A

bases

46
Q

Purpose for temporary restorative materials

A
  • provide short-term protection
  • allow time for permanent restoration construction (eg. indirect restorations)
  • allow time for pulp healing
  • evaluation of pulp
  • treatment plan
47
Q

Direct vs indirect capping

A

Direct capping: when pulp is exposed and visible.

Indirect capping: when there is still a thin layer of intact dentin over the pulp (<0.5mm)

48
Q

pH of CaOH

A

pH = 11, therefore kills bacteria. Also helps create tertiary dentin

49
Q

CaOH disadvantage

A
  • dissolves if leakage occurs

- weak and flexible

50
Q

traditional cements setting reaction

A

basic powder + acidic liquid –> set cement (salt + unreacted powder)

51
Q

Why do we want to maximize the amount of powder incorporated into the liquid?

A

because too much liquid = more matrix = lower mech properties

52
Q

Is zinc oxide soluble or insoluble?

A

insoluble

53
Q

Zinc oxide powder reacts with ____

A

acid

54
Q

Main advantage of zinc oxide?

A

it has an antibacterial effect

55
Q

Primary use of Zinc Phosphate Cements?

A 
luting agent (cast restoration, ortho)
-use when gluing any kind of metallic material to the tooth
56
Q

Do not use zinc phosphate cements if dentin is less than ____. Why?

A

<1.0mm, because Zinc phosphate is acidic and can cause damage to pulp

57
Q

What control rate of reaction in zinc ohsphate cements?

A

buffering salts.

Rate is also affected by temp and water content (accelerate by increasing water)

58
Q

Zinc phosphate cement is mixed over a ____ area. Why?

A

wide area. To dissipate the heat of reaction

59
Q

Why is the frozen slab technique used?

A
  • to increase working time and setting time
  • used when long working time is required
  • more powder can be incorporated the colder it gets
60
Q

Which cement requires that the powder be divided into 6 increments?

A

Zinc phosphate.

Start with 1/16, 1/16, 1/8, 1/4, 1/4, 1/4 added from smallest to largest and mixed for 15 s each.

61
Q

Uses of polycarboxylate cement

A

primarily as a luting agent for cast restorations

62
Q

The reaction of polycarboxylate cement includes…

A

crosslinking polyarylic acid polymer by Zn2+ ions (1 ion connects 2 chains) so the initial setting time is very short

63
Q

polycarboxylate cement is mixed on what kind of surface?

A

on a paper pad. Mixed quickly

64
Q

Polycarboxylate is reactive towards:

A

positive ions. Therefore it will chemically bind to a glass slab (use paper instead), tooth structure, or stainless steel spatula (use plastic instead)

65
Q

define chelation

A

Bonding of ions and molecules to metal ions.

66
Q

ZOE stands for:

A

Zinc oxide eugenol

67
Q

Zinc oxide eugenol is mostly used for:

A

temporary filling material or temporary luting agent. Cavity base.

68
Q

ZOE reaction

A

Zinc Oxide + Eugenol –> Zinc eugenolate + water

69
Q

What can greatly accelerate the reaction of ZOE?

A

Humid environment (such as oral cavity) or mixing with trace amount of water

70
Q

ZOE is typically mixed on what surface?

A

glass

71
Q

What was the first tooth-colored filling material?

A

Silicate cement

72
Q

glass is composed of ___

A

silica

73
Q

In silicate cement, glass is mixed with ___ ___ and a matrix is formed

A

phorphoric acid

74
Q

What do you call metals and metallic salt that will lower the melting point of glass? Give an example of one in dentistry

A

fluxes. Usually fluoride

75
Q

The glass powder in silicate cement and glass ionomer cement is made from a glass fluxed with ___ and ____ ____

A

ALUMINA and SODIUM FLUORIDE

76
Q

Main use of silicate cement in dentistry:

A
  • cements
  • tooth colored filling material
  • was frequently used in patients with very high caries indices
  • low-cost and anti-caries activity (due to anti-bacterial fluoride)
77
Q

Describe in words the basic reaction that occurs during the mixing of silicate cement

A

When the silicate cement is mixed, the acid (phosphoric acid) dissolves part of the glass, releasing ions.
The set cement consists of glass particles and fluoride salts cemented together by the ALUMINUM PHOSPHATE MATRIX

78
Q

Main advantages/disadvantages of silicate cement

A

ADVANTAGES:
-Cariostatic effect due to fluoride release
-initially good esthetics
DISADVANTAGES:
-brittle and has lack of wear resistance causing
-rougher surface
-stains over time
-souble
-low tensile strength
-poor biocompatibility due to high acidity

79
Q

What has silicate cement been replaced by?

A
  • glass ionomer (more aesthetic)

- resin composite material

80
Q

polycarbooxylate cement provides adhesion to enamel due to _____

A

chelation

81
Q

2 most important things about glass ionomer to remember:

A
  1. Provides FLUORODATION

2. Provides ADHESION to the tooth

82
Q

GI uses

A
  • permanent luting agent for cast restorations and ortho bands
  • cavity base
  • liner
  • pit and fissure sealant
  • endodontic sealant
  • permanent restorative material for non-occluding surfaces
83
Q

ISO ADA types of GI

A

Type I - luting
Type II - Restoration
Type III - liners/base

84
Q

What type of acid prevents thickening of polyacrylic acid (PAA-used for GI) during storage?

A

itaconic acid

85
Q

What does tartaric acid do?

A

controls the setting rate of GI

86
Q

The powder/liquid GI system includes a ___ powder and an ____ ____ liquid

A

BASIC powder and an ORGANIC ACID liquid.
Powder: glass powder containing Ca, Al, SiO2 and fluoride.
Liquid: polyacrylic acid, itaconic acid, tartaric acid and water

87
Q

Why does the glass ionomer need to be protected during the first 10 mins?

A

Because it can swell due to saliva imbibition or dry due to syneresis. For this reason, petroleum jelly can be applied until GI has set.

When the polyacrylic acid attacks the glass particle, a silica-based hydrogel is created which releases Al, Ca, and F ions. This is highly sensitive to water.

88
Q

How do GIs reduce likelihood of recurrent decay around the margins?

A

through fluoride release

89
Q

Can GI be used for children?

A

yes

90
Q

What happens to the rate of fluoride release over time in GI?/

A

During the first hours, there is a strong release of fluoride (20ppm). After the first day, this reduces to a much slower rate (1-2ppm)

91
Q

How is fluoride pushed back into cements?

A

by osmotic pressure. THerefore, once fluoride is released, it can be replenished (by brushing teeth with fluoride toothpaste or receiving topical fluoride at dentist)

92
Q

Gi bonds ____ to the tooth structure

A

chemically

93
Q

Main advantages of GI

A
  • bonds chemically to tooth structure
  • fluoride release
  • coefficient of thermal expansion similar to tooth
94
Q

Main disadvantage of GI

A
  • low strength and wear resistance
  • poor esthetic
  • technique sensitive (ie. has to be protected gainst imbibition and syneresis)
  • sensitive to water contamination during placement
95
Q

What is RMGI? What are the advantages/disadvantages of this material?

A

RMGI = resin-modified glass ionomer (80% glass, 20% resin)
ADVANTAGES:
-light cured (longer working time)
-resin prevents syneresis and imbibition (no need for vaseline)
-different colours for more aesthetic
DISADVANTAGES:
-Releases less fluoride than traditional GI (polymer barrier protects GI from water, but also prevents fluoride from being released)

Intro to Dentistry Materials (3 decks)

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