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OPERATIVE II > lecture 2 > Flashcards

lecture 2 Flashcards

1
Q

attraction between similar molecules or atoms

A

cohesion
cohesive failure

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2
Q

attraction between unlike molecules, attraction between two contracting surfaces

A

adhesion
adhesion failure

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3
Q

material bonded to another material by means of an adhesive

A

adherend

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4
Q

substance that promotes adhesion

A

adhesive

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5
Q

joining two materials by means of an adhesive

A

adhesive bonding

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6
Q

adhesion classifaction

A

physical bonding- very weak
chemical bonding- very limited with dissimilar materials
mechanical- interlocking; adhesive interlocks into surface irregularities (THIS IS THE DENTAL ADHESION MECH)

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7
Q

what is the dental adhesion mech

A

mechanical
(micro-mechanical bond want)

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8
Q

microscopically intimate interface= improve _____

A

improve interlocking

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9
Q

the ability of a liquid to maintain intermolecular contact with a solid surface

A

surface wetting

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10
Q

adhesion requirments:

A
  1. microscopically intimate interface= improve interlocking
  2. good surface wetting
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11
Q

improved surface wetting = increased

A

increased surface energy by an increase in surface available for bonding (by etching; roughened surface)

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12
Q

etching transforms smooth enamel into

A

an irregular surface

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13
Q

enamel bonding=
dentin bonding=

A

enamel bonding= very predictable (~25-30 MPa)
dentin bonding= more challenging (bond strength varies)

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14
Q

enamel etching
type I
type II
type III
type IV
type V

A

type I- honeycomb= from dissolution of prism(enamel rod) CORES
type II- cobblestone=from dissolution of prism(enamel rod) PERIPHERIES
type III- combo of I and II
type IV- pitted
type V- Aprismatic (flat and smooth)

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15
Q

what enamel etching types are found in occlusal and middle thirds of teeth which are the best bonds to acheive

A

type I and II

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16
Q

chemical “drilling”

A

acid etching enamel

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17
Q

what is most effective for enamel retention

A

30-40% phosphoric acid

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18
Q

place acid etching ____seconds prior to rinsing and it removes about ____microns of enamel

A

15 seconds prior to rinsing
removes 10 microns of enamel

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19
Q

acid etching creates porous layer ____microns deep

A

5-50

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20
Q

rinse with water ____seconds after etching. why?

A

10 seconds

to remove acid and leave enamel surface clean for bonding

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21
Q

etching increases:

A

wettability and surface area of the enamel

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22
Q

etching raises the surface of FREE ENERGY to exceed:

A

the surface tension of bonding material

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23
Q

this is the mechanical interlocking that we are trying to achieve by producing spaces where resin can penetrate to form resin tags

A

etching enamel

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24
Q

after etching is complete:

A

apply bond agent resin (low viscosity)

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25
Q

bond flows into microporosities and polymerizes to

A

micromechanical bond

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26
Q

what are the bonding systems

A
  1. etch-and-rinse (total etch)
  2. self-etch
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27
Q

explain etch and rinse

A

(total etch)
-etch seperately
-prime
-bond
-or prime + bond combo

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28
Q

explain self-etch

A

-no phosphoric acid-etch step
-acid part of primer or primer/bond agent

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29
Q

if you dont use this step, then you arent getting the smear layer off

A

etching

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30
Q

what bonding system do we use at umkc

A

etch-and-rinse (total etch) with prime+bond combined

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31
Q

what are the two options for etch-and-rinse (total etch) bonding system

A
  1. 3 step(2 bottle) total etch
  2. 2 step(1 bottle) total etch
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32
Q

explain the 3 step(2 bottle) etch-and-rinse bonding system

A

a. etchant
b. primer
c. bonding agent (scotch bond multi-purpose)

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33
Q

explain the 2 step(1 bottle) etch-and-rinse bonding system

A

a. etchant
b. primer and bond agent combined
(like prime and bond NT, PQ1, peak, optibond solo plus)

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34
Q

explain the self-etch 2 step bonding system

A

self-etch primer
a. 2-step: acidic primer and bonding agent
b. acidic primer partially dissolves smear layer, allows penetration of bond resin
(clearfil SE bond example)

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35
Q

explain the self-etch 1 step bonding system

A

self-etching adhesive (all-in-one)
a. 1-step- most variable/least predictable
b. acidic primer and bone resin are one solution
(i-bond; some require mixing)

36
Q

what are the advantages of rinse and etch systm

A

more predictable, STRONGER BOND, enamel adequately prepared

37
Q

what are the disadvantages of rinse and etch system

A

*collagen collapse is possible (by user error)
-etch zone is often deeper than hybrid layer
(exposed demineralized, collagen fibrils)
(post operative sensitivity)

38
Q

self etch advantages

A

-no seperate etch: overdried, collapsed demineralized collagen not a problem
-etched zone and hybrid layer comparable width
-low post-operative sensitivity
-time efficiency

39
Q

self-etch disadvantages

A

-not compatible with self-cure, dual-cure composite
-acidic monomers, low pH, kills the basic amine activator
-will not etch unprepared enamel

40
Q

universal adhesives can be used in:

A

total etch
self etch
selective etch
(etch enamel only with phosphoric acid)

{used at umkc: etch-and-rinse enamel and bond dentin}

41
Q

what allows the universal adhesive to be universal

A

10-MDP

42
Q

mechanism of action for universal adhesive:

A

a monomer that chemically interacts via ionic bonding to calcium in hydroxyapatite

(monomer is a phosphate ester)

43
Q

bond to dentin collagen is influenced by

A

matrix metalloproteinases (MMPs)
-which are collagen enzymes that metabolize unhybridized collagen

44
Q

MMPs are present on ____

A

collagen fibrils

45
Q

this inhibits MMP activation

A

chlorhexidine (cleans up area)

46
Q

adverse pulp rxn comes primarily from

A

bacteria remaining in or penetrating the preparation

47
Q

what are the 5 bonding clinical success requirements

A
  1. knowledge of substrate
    dentin vs. enamel
    deep vs superficial dentin
    caries-affected dentin
  2. good cavity prep and margins
    mechanical retention
  3. rubber dam and matrix wedges
  4. correct use of the bonding agent
    wet/moist bonding, total etch, self-etch
  5. bond agent compatible with resin composite
48
Q

how do bond strengths to dentin vary

A
  1. region of tooth (superficial higher bond strength than deeper)
  2. flat surfaces higher than box cavities
  3. c factor
  4. thickness of increment of comp. resin
    1mm better than 2 mm increments
  5. adhesive system used
  6. operator
  7. intrinsic wetness of tooth
  8. dryness vs wetness
49
Q

the location of adhesion matters

A
  1. incisal third and middle third enamel
    -strong
  2. cervical enamel
    -shorter and fewer enamel tags (compared to incisal and middle third)
    -less prism delineation
    (due to presence of prismless enamel;
    found in cervical third of 70% of teeth)
50
Q

doing these will reduce microleakage at cervical and ascending walls in class II preps

A

bevels and adhesive dentistry

51
Q

bevel what of prep which is necessary when in enamel

A

bevel gingival floor

52
Q

enamel prepared with bur (beveled) etches better because

A
  1. exposes ends of enamel rods
  2. reveals prismatic enamel
53
Q

when do we not bevel

A

deep preps
-when gingival floor is on cementum or dentin

54
Q

this is the goal of adhesive dentistry with composite resin:
in enamel-
in dentin-

A

micromechanical bond
in enamel- interlocking with enamel rods
in dentin- interlocking with dentin collagen

55
Q

enamel make up

A

95-98% inorganic matter by weight
90-92% hydroxyapatite by vol
1-2% organic matter by weight
4% water

56
Q

enamel

perpendicular oriented enamel

parallel oriented enamel

A

perpendicular oriented enamel:
-cavosurface margins of class I preps
-bevels of class II preps
-ends of enamel rods

parallel oriented enamel:
-internal walls of occlusal preps
-gingival floor of box of class II preps
-sides of enamel rods

57
Q

this increases surface area and surface energy by allowing wetting of tooth

A

etch surface

58
Q

by etching, this allows wetting the tooth with

A

hydrophobic adhesive resin (remember enamel has minimum water)

59
Q

what interlock?

A

resin tags
-micro and macro tags into surface irregularities

60
Q

dentin characteristics

A

55% mineral by volume
30% collagen
15 % water

dentin is very heterogenous

61
Q

dentin anatomy review.
tubules are:
very inorganic:
very organic and collagen rich:

A

tubules are: fluid filled
very inorganic: peritubular dentin
very organic and collagen rich: intertubular dentin

62
Q

dentin tubule diameters
near DEJ:
near pulp:

A

near DEJ: .5 um
near pulp: 2.5 um
(larger near pulp

63
Q

deeper you go into dentin, the

A

more and wider the tubules are= more fluid and less intertubular dentin

64
Q

mix of tooth debris, often contaminated with saliva, blood, cells, and bacteria

A

smear layer

65
Q

do you bond to smear layer?

A

NO

66
Q

remove smear layer with

A

acid etch

67
Q

intermingled layer of collagen and resin

A

hybrid layer

68
Q

this layer is what we want to form when bonding to dentin

A

hybrid layer

69
Q

problems forming the hybrid layer

A

must be the perf balance
-avoid over etching
-overdrying
-under drying

70
Q

steps of forming hybrid layer properly

A
  1. acid etch 15 seconds on dentin (less time than enamel)
  2. wash and LIGHTLY dry
    =*hydroxyapatite removed, water remains to support collagen fibers
  3. apply primer
  4. apply adhesive
  5. light cure

hybrid layer forms!

71
Q

over-etching=

A

results in underfilled restorations

-means acid etched too long
-demineralized zone too thick
-primer cant infiltrate far enough
-leaves unprotected layer

72
Q

over-drying =

A

results in lower bond strengths

-collagen collapses=lower bond strength

73
Q

under-drying=

A

excess water
-poor hybrid layer formed
-resin unable to infiltrate intertubular dentin
-“blister spaces” where primer and adhesive seperate

74
Q

what are the disadvantages of bonding systems

A

-too many steps= operator errors
-dont remove smear layer
-delicate treatment of dentin necessary

75
Q

phosphoric acid gel (30-40%)

A

etchant

76
Q

HYDROPHILIC monomers in HEMA solvent
-acetone, ethanol/water, water

A

primer

77
Q

HYDROPHOBIC dimethacrylate monomers
-initiators and activators

A

adhesive bonding resin/agent

78
Q

polymerization process (setting up process)
adhesive/primer is a chemical rxn that takes monomers to->

A

polymers

79
Q

this concerts initiator(chemical) into a free radical
-free radial starts polymerization rxn
-light or chemical

A

activator

(part of polymerization process)

80
Q

light as an activator explained

A

light: (blue light 570nm for composite)
camphorquinone-> free radical-> polymerization reaction

81
Q

chemical as an activator explained

A

chemical (tertiary amine)
benzoyl peroxide(initiator)-> free radial -> polymerization reaction

82
Q

bonding procedure steps

A
  1. acid etch
    20s enamel
    15s dentin , if doing so
  2. rinse
    10s
    gently dry- enamel should be dry, dentin slightly moist
  3. apply primer (not if using adhese universal )
  4. bond
  5. cure
    initiate polymerization for 20s
  6. place composite
83
Q

dentin bonding mechanism
1. this demineralizes collagen fibrils=
2. this supports collagen network=
3. this this applied to polymerized=

A
  1. acid-etched
  2. water
  3. dentin bond agent
84
Q

primary dentin bond mechanism is from

A

hybrid layer

85
Q

there is better bond strength in ___dentin

lower bond strength in ___dentin

A

superficial dentin

carious dentin

86
Q

moist vs. dry dentin?

A

moist is better

OPERATIVE II (11 decks)

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