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DEN2SKC > WEEK 8 > Flashcards

WEEK 8 Flashcards

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1
Q

Define smear layer

A

layer of cutting debris, microorganisms, and salivary proteins.

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2
Q

How does the smear layer vary?

A

in thickness, density, and levels of attachment.

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3
Q

Why do we need to remove the smear layer?

A

it occludes the tubules needed to utilise resin tags

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4
Q

What documents do we follow for guidelines for infection control?

A

ADA, dental board of australia, national health and medical research council, standards australia, and clinical infection control manual.

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5
Q

What are semi critical instruments?

A

contact oral mucosa without penetrating soft tissue or bone
- mouth mirror, receptor holding device

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6
Q

what do we do with semi-critical instuments?

A

sterilize them, or they’re single use

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7
Q

what are critical instruments?

A

objects that penetrate sterile tissue. burs or forceps

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8
Q

what do we do with critical instruments?

A

must be sterilized.

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9
Q

what are non-critical instruments?

A

instruments that contact intact skin. bib chain or glasses

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10
Q

what do we do with non-critical instruments?

A

thermally disinfect them or clean them

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11
Q

how do we clean instruments?

A

detergent, water, and a physical action. Always done prior to sterilization.

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12
Q

How do we disinfect instruments?

A

thermal (heat and water), or chemical (alcohols, formeldahydes, amonia, etc)

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13
Q

what gets removed in “high levels” of disinfectant

A

endospores

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14
Q

what gets removed in “intermediate” disinfectant

A

microbial pathogens (bacteria, fungi, virus)

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15
Q

what gets removed in “low” disinfectant

A

Vegetative bacteria and some viruses

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16
Q

what is an ultrasonic cleaner?

A

mechanical cleaner using water and cleaning solutions

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17
Q

what is the maintenance involved with ultrasonics?

A

filled at least twice a day, drained and cleaned at end of day.

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18
Q

What is the more effective cleaner than ultrasonics?

A

thermal washer disinfector.

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19
Q

what do you have to do to instruments before and after putting them in a manual cleaner?

A

rinse with warm water before, remove visible soil. After, they have to be rinsed to remove gram negative heat tolerant bacteria and thoroughly dried before sterilization.

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20
Q

what does sterilization do?

A

renders instruments and devices free of all forms of micro-organisms.

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21
Q

how do sterlizers work?

A

with steam and pressure

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22
Q

what is the temperature and holding time of sterilizers.

A

134-137 degrees celsius, 3 mins

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23
Q

what does N mean in an autocleave cycle?

A

unwrapped solid items

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24
Q

what does B mean in an autocleave cycle?

A

wrapped or unwrapped, porous and canulated, type A hollow objects

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25
what does S mean in an autocleave cycle?
specified
26
what do critical items need to have on their pouch?
Batch control ID
27
what is included in batch control ID?
date of sterilization, which autocleave it came from, autocleave cycle number.
28
what is a sterilizer cycle record book?
legal written document acting as evidence of correct reprocessing practices. A log that shows the date, cycle number, load type, cycle program, ID of loading operator
29
how long does cycle data have to be retained?
7 years
30
How can contamination happen when storing clean instruments?
overhandling, moisture, exposed packaging, placement onto contaminated surface.
31
what is a hybrid layer?
an interface of tooth and resin, where the cured bonding resin is interwoven with the collagen fibers and partially penetrated tubules.
32
how do you get a hybrid layer?
microporosities of the tooth are infiltrated by a synthetic resin and are polymerised.
33
what is a synthetic resin?
the final solid material after light curing the bond
34
what is polymerisation?
Monomers are converted into polymers by breaking the double bond in the resin monomer (usually Bis-GMA) with the help of a free radical. The final result is a strong, cross-linked polymer that has increased rigidity and durability.
35
What role do ethanol and water-based solvents play in dental adhesives?
They help carry methacrylate monomers into dry or moist dentin, optimizing infiltration of the adhesive.
36
What do methacrylate monomers do in the bonding process?
They infiltrate the demineralized dentin and polymerize to form a strong hybrid layer.
37
How do acidic monomers contribute to dentin bonding?
They react with calcium in dentin to form insoluble calcium salts, which help seal dentinal tubules and promote a stable bond.
38
What is the effect of calcium salt precipitation in dentinal tubules?
It facilitates mechanical blockage and sealing of the tubules, enhancing marginal integrity and bond stability.
39
What are resin tags and what is their function?
Resin tags are extensions of cured adhesive that penetrate dentinal tubules; they block fluid movement, reducing post-op sensitivity.
40
How does adhesive bonding reduce post-operative sensitivity?
By forming resin tags that block dentinal fluid movement and by sealing the tubules, creating a desensitizing effect.
41
Why is air used after applying adhesive with ethanol/water solvents?
To evaporate the solvent and leave a thin, uniform adhesive layer on the dentin.
42
Why is a low film thickness in the adhesive layer important?
It ensures optimal fitting accuracy of indirect restorations like crowns or veneers.
43
What is the difference between methacrylate monomers and acidic monomers in dental adhesives?
Methacrylate monomers are resin molecules that polymerize to form a durable adhesive layer. Acidic monomers are a type of methacrylate that also contain acid groups, allowing them to mildly demineralize tooth surfaces and chemically bond to calcium in enamel and dentin.
44
How do hydrophilic and hydrophobic monomers optimize adhesive bond?
the tooth is hydrophilic and the restorative material is hydrophobic
45
How does photo-initiatory chemistry work?
it provides more free radicals when curing which relates to higher monomer conversion rates and therefore a stronger bond.
46
referring to clearfil SE Bond 2, how long do you leave primer on?
20 secs, dry with mild airflow for 5 secs
47
referring to clearfil SE Bond 2, what are the steps after primer?
apply bond, make uniform with mild airflow, light cure, apply and light cure composite.
48
when placing dental adhesives, why do we have to agitate the tooth surface?
to maximize the depth of penetration of the resin layer. the greater the penetration, the greater the shear strength of the hybrid layer.
49
what happens if you apply a really thick layer of bond?
reduces strength and is more prone to fracture under restoration, leading to post op sensitivity and failure of restoration due to polymerization shrinkage.
50
What is polymerization shrinkage and why is it a concern in dental bonding?
Polymerization shrinkage is the volume reduction that occurs when resin monomers link to form polymers. It creates stress at the adhesive interface, which can lead to gaps, debonding, microleakage, or sensitivity.
51
What is the role of solvents in dental bonding systems?
help carry resin monomers into demineralized dentin, displace moisture, and reduce viscosity for better flow. They evaporate to leave a thin adhesive layer when you airdry the bond.
52
why is it important to evaporate the solvents in bond with airflow?
If you don't you will get water sorption, which weakens the polymer network and reduces bond strength over time.
53
what is water sorption?
residual solvent acts like a sponge trapping water from the oral environment, and causes hydrolytic degredation. This is the swelling of the polymer causing the network to break down.
54
what causes adhesion?
primarily micromechanical interlocking (95%) but also chemical interaction.
55
what makes a type of bond good?
initial and permanent strength, good biocompatitibility, recuces microleakage, compatible with a range of resins, not too many steps.
56
what does good biocompatibility mean?
non-toxic, non-sensitizing, doesn't aggravate pulpal complex.
57
what are common resin monomers?
BIS GMA, TCB
58
what do fillers do in dental adhesives?
improve strength, prevents excessive thinning
59
What is the function of primers in dental adhesives?
Primers are composed of hydrophilic monomers that support the collagen network by preventing it from collapsing, allowing better resin infiltration and creating a stronger bond.
60
what do stabilizers do in dental adhesives?
prevent degradation of adhesion over time
61
why is fluoride in dental adhesives?
desensitizer
62
what are the components of a setting reaction?
activation, initiation, propagation, termination
63
what is activation in a setting reaction?
external stimulus is applied to prep resin monomers for polymerization.
64
what is initiation in a setting reaction?
activation of a photoinitiatior by exposure to curing light
65
what is propagation in a setting reaction?
polymerization propagating throguh resin monomers leading to the formation of a polymer chain. the continued growth of the chain solidifying the adhesive.
66
what is termination in a setting reaction?
end of polymerization, or completion of the polymer chains.
67
What do "wetting" and "intimate adaptation" mean in terms of dental adhesion?
Wetting is the adhesive's ability to spread and penetrate into the tooth structure, while intimate adaptation refers to the adhesive's ability to fit closely and precisely to the tooth surface at a microscopic level, ensuring a strong bond.
68
Hydrophilic adhesives:
Found in primers to work well with wet dentin.
69
Hydrophobic adhesives:
Used in the bonding resin layer to bond effectively to enamel and dry dentin.
70
Superhydrophobic adhesives:
Strong water-repellent properties, often used for specialized applications
71
explain the different moisture levels in the tooth and how it relates to wettability.
Dentin is naturally more moist and requires a primer with hydrophilic properties to effectively bond, especially after acid etching. Enamel is much drier, and bonding adhesives that are hydrophobic tend to perform better on dry enamel surfaces.
72
what does etch do?
creates surrafe irregularities to enhance micromechanical interlocking. Increases surface area, increases energy to enhance wettability. removes smear layer
73
How does etching increase the energy of the tooth surface to enhance wettability of resin monomers?
This higher surface energy allows resin monomers to spread more easily and penetrate the surface, leading to a stronger bond.
74
how long do we agitate etch for?
20 seconds
75
how deep does etch penetrate?
30 micrometers
76
what does overdrying do to collagen fibres?
desiccates them. They are supported by water, and if overdried they will collapse, preventing resin from deeply penetrating.
77
which tooth material is more reliable for bonding?
Enamel. dentin has water that competes with bonding agents as it is 70% inorganic, 20% organic, and 10% water.
78
how do the tubules in dentin affect its bonding properties?
they are a passageway to allow bacteria and toxins to interact with pulpal tissue. The constant outward motion of fluid through the tubules is what causes the wet surface of dentin.
79
what is 5th generation bond?
acid seperate, bond and prime together.
80
what is 6th generation bond?
self etch, etch and prime in one bottle. adhesive separate
81
what is 7th generation bond?
all three in one bottle
82
what is 4th generation bond?
etch, prime, adhesive all separate bottles.
83
what percent of phosphoric acid is etch?
37%

DEN2SKC (13 decks)

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