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Fixed Midterm Spring > All Readings > Flashcards

All Readings Flashcards

1
Q

Goal of management of gingival tissues is to

A

maintain the normal appearance of healthy gingiva

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2
Q

In order to maintain the normal appearance of healthy gingiva what must take place

A
  • Minimal trauma during treatment

- Optimal gingival health before the treatment

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3
Q

The best way to minimize trauma to gingival tissues it to minimize their contact with what

A

restorative materials (hence why supragingival margins are optimal to reduce perio issues and gingival inflammation )

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4
Q

Maintenance of subgingival margins can be achieved if what is done

A
  • Well-fitting flush margins
  • Proper contours
  • Reversible gingival tissue displacement
  • tissue management
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5
Q

Before attempting tissue displacement the characteristics of the gingiva should be as follows

A
  • Healthy
  • Firm
  • Non-bleeding
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6
Q

Steps involved in periodontal evaluation of the teeth are

A
  • 1=Radiographic exam
  • 2=Visual inspection (color, contour, consistency, position, surface texture and presence of pain)
  • 3= Measure sulcus depth
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7
Q

What are the two types of trauma the gingiva are exposed to during gingival displacement

A
  • Mechanical

- Chemical

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8
Q

Describe the trauma to the gingival tissues caused by chemicals

A

Cords + astringents are cytotoxic to gingival fibroblasts

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9
Q

T/F the injury inflicted by displacement cords is irreversible and progressive

A

F- it is reversible and self-limiting

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10
Q

People’s gingiva is more likely to recover from the trauma in prosthodontics if….

A

their tissue is healthy (existing perio abnormalities –> exaggerated responses to slight tissue insults)

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11
Q

People that require gingival displacement typically have the margins _-_mm subgingivally

A

0.5-1 mm

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12
Q

Why is knowing the probing depths important before tissue displacement

A

Because then you can determine how deep the finish line can be placed and if it will be possible to achieve enough displacement

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13
Q

When choosing the displacement technique what should be the factor to consider

A

the type of tissue being manipulated

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14
Q

What are the two biotypes of tissues

A
  • Thick, flat biotype

- Thin and scalloped biotype

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15
Q

In a thick flat biotype there is (minimal/maximal) distance between the midfacial gingival crest and the height of the interdental papilla

A

minimal

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16
Q

Thick flat biotype typically has (smaller/larger) probing depths and the gingival margin is typically located at (enamel/CEJ/Cementum)

A

larger… Enamel

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17
Q

People with thick flat biotype have (a lot/a little) scalloping at the alveolar crest with (little/significant) incidence of bony fenestrations and dehiscences

A

a little…. little

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18
Q

Thin scalloped biotype typically has (smaller/larger) probing depths and the gingival margin is typically located at (enamel/CEJ/Cementum)

A

smaller (shallower)… CEJ or cementum (pretreatment recession)

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19
Q

People with thin scalloped biotype have (a lot/a little) scalloping at the alveolar crest with (little/significant) incidence of bony fenestrations and dehiscences

A

a lot …significant

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20
Q

The distance between the CEJ and bone in thin scalloped biotype is typically _mm

A

4

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21
Q

In thin scalloped biotype there is (minimal/maximal) distance between the midfacial gingival crest and the height of the interdental papilla

A

maximal

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22
Q

Subgingival margins in people with thin biotype should be avoided because

A

will likely cause additional recession

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23
Q

The epithelial attachment is a zone of attachment that contains

A

JE

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24
Q

T/F Epithelium doesn’t regenerate after surgery

A

f

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25
Q

Epithelial attachment is connected to (enamel/dentin/cementum) via _

A

enamel and cementum via hemidesmosomes

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26
Q

Restorations shouldnt extend beyond _-_mm into the gingival sulcus

A

0.5-1

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27
Q

_mm sarftey zone between the crest of the alveolar ridge and the margin of the crown should be maintained

A

3mm

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28
Q

T/F It is not possible to detect clinically where the sulcus ends and the JE begins

A

t

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29
Q

Consequences of invading biologic width are

A

marginal and papillary gingivitis which can lead to chronic inflammation and progress to periodontitis

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30
Q

The amount of pressure generated by displacement cords is significantly (higher/lower) than cordless displacement

A

higher

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31
Q

Consequences of heavy forces when placing displacement cords are

A
  • Gingival recession

- Loss of attachment

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32
Q

Clinicians are more likely to apply greater force when placing displacement cords under what circumstances

A

when the patient is anesthatized

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33
Q

T/F It is important to not leave the cords in the suclus for too long

A

t

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34
Q

T/F No harmful effects on epithelial attachment when cords are placed carefully and for a reasonable amount of time in patients with healthy gingiva

A

t

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35
Q

The amount of time needed for cords to remain in sulcus is

A

5 mins (1-30 min)

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36
Q

Cords must remain in the sulcus for a min. of 4 mins to provide

A

sufficient crevicular width expansion

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37
Q

T/F long term damage to periodontium is seen when short placement times of cords are used

A

f

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38
Q

T/F displacement cords cause destruction of the JE

A

t

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39
Q

How long does it take for JE to heal after placement of displacement cords

A

5-14 days

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40
Q

What is the most popular method of tissue displacement

A

displacement cords

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41
Q

Primary cords used are

A

Braided and Knitted

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42
Q

Issues with cords dispensed from a container are

A

cross contamination

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43
Q

Which type of cord is easier to pack/place and why

A

braided because it has a consistent tight weave making them resistant to separation during placement. They don’t split or tear during placement

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44
Q

Braided cords must be placed with (smooth/serrated) instruments contrary to knitted where you must use (smooth/serrated)

A

Both… smooth (non-serrated)

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45
Q

Placing the cord should start where along the tooth

A

interpoximally

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46
Q

What cords are able to expand when wet

A

knitted

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47
Q

When placing a cord in thin biotype gingiva with minimal sulcus depth the instrument of choice is

A

perio probe

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48
Q

Most prosthodontists soak their cords in what astringent

A

Aluminum chloride

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49
Q

Epinephrine in cord displacement is known to cause

A
  • Adverse CV problems (HTN, and increased HR)
  • Increased respiratory rate
  • Tachycardia
  • Rare (death)
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50
Q

There is about _x more epi in 1 inch of displacement cord than _

A

50x… 1 carpule of 1:100,000 epi

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51
Q

Describe how epi can lead to a less than idea gingival response for some patients

A

Epi can expose underlying CT and setup a wound-healing response

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52
Q

T/F Epi should be avoided for tissue displacement

A

T- esp in patients with CV issues

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53
Q

(T/F) In an experiement looking at aluminum sulfate and epi the clinician couldn’t tell the difference

A

T

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54
Q

Composition of astringents

A

metal salts

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55
Q

Describe the mechanism of astringents

A
  • Contraction of gingival tissue by contraction of BVs

- Makes the tissue tougher (decreases exudation)

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56
Q

Extended contact between gingiva and astringents can lead to

A

delayed healing or tissue damage

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57
Q

Astringents are (acidic/basic) and remove the_

A

acidic… smear layer

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58
Q

Removing the smear layer by the astringents has what consequences

A

post-op sensitivity

affects the bonding mechanism of adhesive cements

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59
Q

Hemostatic agents are available in what forms

A
  • Liquid
  • Gels
  • Pastes
  • Foam
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60
Q

Conc. of AC (aluminum chloride) is most commonly

A

20-25%

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61
Q

Buffered AC was introduced to…

A

prevent irritation of gingiva

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62
Q

T/F Soaking cords in astringent affects its ability to absorb fluid and expand in the sulcus

A

f

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63
Q

T/F There is evidence to suggest that hemostatic agents inhibit the setting of PVS

A

F- but there is conflicting data

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64
Q

Interference in the quality of surface detail of PVS by hemostatic agents is primarily due to

A

sulfur (esp in ferric sulfate)

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65
Q

What is the component of ferric sulfate that leads to staining of dentin and gingival tissue

A

iron

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66
Q

In order to prevent FS from affecting the surface detail reproduction of PVS what must be done

A

rinse FS thoroughly

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67
Q

A cord impregnated with Alum can safety be left in the sulcus for as long as _ without adverse effects

A

20 mins

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68
Q

Unibraid cords are preimpregnated with

A

10% Alum

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69
Q

Cordless displacement materials (CDM) are available in what forms

A

pastes, foams, gels

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70
Q

CDM contains what conc. of what active ingredient

A

15% AC (cluminum chloride)

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71
Q

High conc. of AC is considered >_%

A

10

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72
Q

High conc. AC can cause

A

local tissue damage
Transient ischemia
tooth sensitivity

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73
Q

Which are less traumatic to gingival tissues (displacement cords/CDM)

A

CDM

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74
Q

Advantages of CDM are

A
  • Less tissue trauma compared to displacement cords
  • Less painfull
  • Quicker to deliver
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75
Q

CDM is preferred for tissue displacement when

A
  • Around cement-retained implant prosethsis

- CAD CAM

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76
Q

Indications for single cord technique

A
  • Impression for small number of abutments with healthy tissues and no hemorrhage
  • Supragingival margins (or juxtagingival)
  • Sulcus depth isn’t deep enough for a 2nd cord
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77
Q

In the single cord technique the cord can be either removed or left in place if…

A

the finishline is completely visible

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78
Q

If the tissue collapses over the finishline and a good impression can’t be obtained what is recommended

A

Electrosurgery (ES)

Soft tissue laser

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79
Q

Double cord technique indicated for

A
  • Single or multiple abutments
  • Subgingival margin
  • First cord doesn’t maintain lateral tissue displacement
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80
Q

(T/F) Double cord technique –> more trauma than single cord

A

T

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81
Q

In double cord technique which cord is presoaked and which is impregnated

A 
presoaked= 1st
impregnated= second
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82
Q

First cord in double cord technique is left in the sulcus during the impression to…

A
  • Control bleeding
  • Prevent collapse of tissue
  • Reduce tearing of impresison material
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83
Q

Desication of the cords and the tissues leads to

A
  • Increased chance of bleeding upon cord removal

- Adherence of impression material to first cord –> increased changes of impression tearing

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84
Q

Electrosurgeryis also referred to as

A

Dilation or troughing

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85
Q

ES is mostly used to

A
  • Reduce hyperplastic tissue
  • Expose gingival margins
  • Prevent bleeding
  • Widen the sulcus without reducing the height of the gingival margin (access for impression material
  • Facilitates impression removal without tearing or marginal material
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86
Q

ES is contraindicated in patients with

A
  • Pacemakers
  • Implanted cardioverter defibrilators
  • Esthetic regions (unpredictable healing)
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87
Q

Soft tissues return to normal apparance after ES after

A

7-10 days

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88
Q

T.F Some Gingival height is lost after ES

A

t- VERY insignificant (0.5-1 mm)

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89
Q

Most painful areas after ES are

A

Palatal of maxillary anteriors and third molars

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90
Q

What is recommended for post-op ES pain

A

OTC analgesics

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91
Q

T/F results after rotary curettage for gingival displacement are predictable

A

f

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92
Q

What lasers are most commonly used for tissue displacement and why

A

diode because of their low wavelength (infrared spectrum)

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93
Q

Overextended provisionals can lead to

A

a periodontal lesion

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94
Q

Indirectly fabricated provisionals yeilds (better/worse) marginal adaptation over direct fabrication

A

better

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95
Q

Advantages of indirectly fabricated provisionals are

A
  • Reduced chair time
  • Reduced occlusal adjustments
  • Optimal contour over axial contours and occlusal morphology
  • Reduced pulpal trauma from chemicals and pulpal trauma associated with direct fabrication
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96
Q

Disadvantage for indirect provisionals

A
  • Fee for pt

- lab steps

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97
Q

The marginal precision od a dental restoration on average is _um

A

50

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98
Q

T/F Intra-oral scanners for CAD CAM technology are now available and replace the need for a impression

A

t- but they are very expensive- not accessible to all dentists yet

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99
Q

Without an intra-oral scanner can you still mill a crown with CAD CAM

A

yes- need an impression though (scan the gypsum model)

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100
Q

Level of hydrophobicity of PVS was reduced how

A

addition of surfactants

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101
Q

PVS is most well know for

A

dimensional stability

-Great elastic recovery even in climates with varying moisture, temperature, and over time

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102
Q

Impression material ideal properties are

A
  • Dimensional stability
  • Accurate
  • Elastic recovery
  • Tear resistance
  • Sets in reasonable amount of time
  • Biocompatible
  • Hypoallergenic and non-toxic
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103
Q

According to the ADA elastomeric impression materials must be able to reproduce details of _um of less

A

25

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104
Q

PVS materials can reproduce details as small as

A

1-2 um

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105
Q

The (higher/lower) the viscosity the better it records fine details

A

lower

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106
Q

Putty materials are required only to record details of _u m

A

75

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107
Q

Define elastic recovery

A

Ability of material to return to original dimensions without significant distortion upon removal from mouth

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108
Q

For all impression materials the greater the depth of the undercut the (more/less) significant the distortion

A

more

109
Q

Minimum thickness of material in tray should be a - times more than the largest undercut

A

3-4

110
Q

What should be done to maximize the elastic recovery of the impression

A

block out undercuts

111
Q

What material has the best elastic recovery? Rank them all from best to worst

A

pvs (over 99%) > polyethers> polysulfides

112
Q

PVS elastic recovery is best when… compare this to polyethers

A

PVS- best immediately after mixing

Polyether= remains plastic long after mixing

113
Q

Define dimensional stability

A

ability fo material to maintain accuracy over time (pour at convenience of operator)

114
Q

Rank the impression materials from best to worst dimensional stability

A

PVS (addition silicone)> Polyether> Polysulfide> condensation silicone

115
Q

For max. accuracy it is suggested to pour a polyether impression _ after removal from mouth

A

1 hr

116
Q

Condensation silicone, polysulfide should be poured _ after removal from mouth

A

30 min

117
Q

What are the volatile endproducts of condensation silicone and polysulfide

A

ethyl alcohol and water respectively

118
Q

Significance of the volatile en-products

A

reason for poor dimensional stability of these impresison materials

119
Q

Hydrophilic nature of impression material relates to its ability to

A

flow better in moist areas and subgingivally with more accuracy

120
Q

More hydrophilic materials have what advantages

A
  • Less air bubble trappying

- Higher precision (esp. subgingivally)

121
Q

Addition of _ increases the hydrophilicity of PVS which does what

A

surfactants… improves wettability and reduces contact angles… impression is more accurate and easier to pour

122
Q

Hydrophilic impression materials are more prone to what issues

A

-mositure absorption –> issues with dimensional accuracy (hence why there is no perfect impression material)

123
Q

Rheological properties means

A

flow characteristics

124
Q

Impression materials must be able to flow into spaces as small as _-_um

A

20-70

125
Q

Neewer light body materials are now _ meaning they remain in place when ejected from syringes but flow under the force of a heavier body material

A

thixotropic

126
Q

Advantage of flexible impression materials

A

easier to retrieve from mouth and more forgiving with undercuts and easier to retrieve gypsum cast

127
Q

Most rigid impression material is _ leas is _

A 
most= polyether
least= alginate
128
Q

Polyether due to the rigidity are not indicated for

A

-Thin preps on periodontally involved teeth

129
Q

Define thixotropy

A

When a material has a high rate of flow under pressure but not under gravity

130
Q

Main difference between the viscosities of the impression materials are

A

amount of inert filler in the material

131
Q

Lower viscosity impression material gives better fine detail replication but has…

A

more polymerization shrinkage- thus want to use as little low viscosity material as needed

132
Q

PVS and polyether may react with

A

remnants of hydrogen peroxide

133
Q

T/F Metal salts (in astringents) may inhibit PVS and polyether setting

A

t

134
Q

In addition to metal salts what else may inhibit setting of impression material

A

methacrylate composites (in core build ups, temps, etc)

135
Q

Removal of methacrylate composites is done with

A

alcohol follwoed by water then dried

136
Q

Custom trays made of PMMA (auto-cure) must rest _ long to ensure end of shrinkage

A

12 hrs

137
Q

What impression materials are affected by latex

A

PVS only

138
Q

Example of polyether impression material is

A

impregum

139
Q

polyethers are (midly/moderately/significantly) hydrophilic

A

moderately

140
Q

T/F Polyether enables multiple pours of accurate casts for 1-2 weeks

A

t

141
Q

Rigidity of polyether is a disadvantage when

A
  • Fixed appliances in mouth (bridges*)
  • Open gingival embrassures
  • Loss of periodontal support
  • Fractures gypsum casts frequently
142
Q

Strict disinfection of polyether impressions should be done to prevent

A

expansion of the material

143
Q

Disinfection of polyether impression should be done with what material and for how long

A

sodium hypochlorite for 10 mins

144
Q

Setting time for polyether

A

10=15 mins

145
Q

What is the most widely used impession material in dentistry

A

PVS (aka addition silicone)

146
Q

Curving of PVS leads to what byproducts

A

H2

147
Q

H2 scavengers for PVS are

A

Pt and Pd

148
Q

PVS can be contaminated with

A

sulfur compounds such as latex (gloves or RD) both direct and indirect inhibition

149
Q

PVS is best used with what material for a custom try

A

acrylic resin

150
Q

Refrigeration of PVS will do what

A

increase the working time by about 1.5 min (will not affect the accuracy)

151
Q

Polysulfides are also called

A

-Thiocols or “rubber base” or mercaptan

152
Q

Describe the hydrophilicity of polysulfides

A

low to moderatly hydrophilic

153
Q

Advantages and disadvantages of polysulfides

A

Advantages

  • Often capture a subgingival margin without tearing better than PVS
  • Easily removed

Disadvantages

  • Fair dimensional stability
  • Poor elastic recovery
  • Long set time
  • Pour immediately
  • Strong bitter taste
154
Q

Why should polysulfide impressions be left in the mouth 5 min beyond clinical set time

A

elastic recovery increases as more time pases

155
Q

Setting time for polysulfide is

A

LONG 12 mins

156
Q

Polysulfide should not be disinfected longer than _ and why

A

10 mins avoid swelling

157
Q

Most common use for condensation silicones

A

lab putty

158
Q

Condensation silicone setting results in the evaporation of _ resulting in

A

alcohol … shrinkage

159
Q

Who introduced the first feldspathic porcelain crown

A

land

160
Q

What was added to feldspathic porcelain to increase the strength

A

Aluminum oxide (Al2O3)

161
Q

A bridge min. connector height of - is needed for all ceramic restoration

A

3-4 mm from the interproximal papilla to the marginal ridge

162
Q

Contraindications for all ceramic FDP

A
  • Reduced interocclusal clearance (short clinical crown, deep vertical overlap, supraeruption)
  • Parafunction
163
Q

Law of beams

A

deflection is inversely proportional to the cube of its height

164
Q

Failures for all ceramic FDP compared to PFM

A

All ceramic= fracture of porcelain

PFM= fracture of tooth and caries

165
Q

According to law of beams how can we reduce the possibility of failure

A

increase the occlusal-gingival height of the connectors to reduce bending

166
Q

Empress 2 is off the market and was replaced with

A

e.max pressed and CAD

167
Q

(T/F) Leucite can be used for 3 unit bridge in anterior/PM region

A

F- single unit only

168
Q

Vital Mark II is what kind of material

A

feldspathic porcelain for CEREC machine

169
Q

Describe the multi-colored ceramic block

A
  • Designed to overcome esthetic disadvantage of monochromatic restorations
  • Inner third= opaque dark base layer
  • Middle third= neutral zone
  • Outer third= more translucent
170
Q

T/F Alumina based ceramics are still used today

A

f

171
Q

Example of alumina based ceramic was

A

procera

172
Q

What was an advantage of procera

A

highest strength alumina based restoration

173
Q

Tetragonal to monoclinic transformation of zirconia leads to -% volume (expansion/contraction)

A

3-5% expansion

174
Q

Tensile stresses causing a crack lead to transformation of what phases in zirconia

A

tetragonal to monoclinic

175
Q

Increased radiopacity of zirconia improves radiographic interpretation of

A
  • marginal integrity
  • excess cement removal
  • recurrent decay
176
Q

yytrium oxide is manufactured through

A

CAD CAM

177
Q

Strength of an ACC is dependent on

A
  • Material used
  • Bond strength
  • Crown thickness
  • Design of restoration
178
Q

Marginal discrepancy: Range for subgingival margins= _-_um and supragingival= -

A

34-119um

2-51 um

179
Q

What is the limit for clinically acceptable marginal discrepancy

A

120 um

180
Q

Poor marginal adaptation can lead to

A
  • cement dissolution
  • microleakage
  • Increased plaque retention
  • secondary decay
181
Q

CAD CAM factors that may influence marginal integrity are

A
  • Software limitations
  • Hardware limitations
  • Scanning and milling equipment
  • Internal cutting bur may be larger than areas of the tooth prep
182
Q

Issues with scanning with a contact probe are

A
  • can’t accurately capture deep and narrow retentive features like grooves and boxes and feather-edge finishlines
  • Can’t capture features less than 2.5 mm wide and more than 0.5 mm deep
183
Q

Cements that don’t work will with ACC restorations are

A
  • Zinc phosphate
  • Zinc polycarboxylate
  • conventional GI
184
Q

Why are zinc phosphate, zinc polycarboxylate and GI poor cements for ACC

A

because they set with a acid base reaction which exacerbates the surface slows in ceramic restorations
**Non-acid base cements recommended for ACC)

185
Q

Why is RMGI ok for ACC

A

because it has two mechanisms of setting (acid base and photo-/chemical curing)

186
Q

What etching provided the best bond strength in ACC

A
  • 5-9.5% HF acid

- 37% phosphoric acid + silane coupling agent

187
Q

Bond between feldspathic and tooth is achieved with

A

silane coupling agents in composite resins

188
Q

Why is resin adhesive cement recommended for ACC

A

-Higher flexural strength (320 MPa) and better seal (less microleakage)

189
Q

Issues with RMGI as ACC cements are

A

-Water absorption and expansion (this is the case for all dual cure resins)–> cracks in brittle ceramic restorations (current ceramics are less susceptible to this)

190
Q

T/F Margins below the CEJ result in loss of adhesion

A

t

191
Q

Which transmits more light (enamel/dentin)

A

enamel- enamel is very translucent

192
Q

T/F The esthetic revolution began after it was determined that mercury vapor is released from amalgam fillings

A

f- at same time

193
Q

T/F No statistical difference in the measures of mercury in patients with amalgam fillings verses composite

A

t (no mercury toxicity linked to amalgam fillings)

194
Q

Why does leakage of amalgam decrease with time in mouth

A
  • Despite only reasonably close adaptation to prep walls

- corrosion products form at the interface –> less leakage over time

195
Q

Advantages of inlays/onlays over direct restorations

A
  • Better marginal fit (controversial)
  • better proximal contacts
  • More anatomic form
  • Color matching (highly esthetic)
  • Less polymerization shrinkage
  • Better access
  • Better wear resistance (controversial)
196
Q

Failure of inlays and onlays mostly due to

A

fracture and caries

197
Q

Contraindications for inlays and onlays are

A
  • Bruxism patients
  • poor OH
  • Opposing teeth with composite restorations
  • Teeth with insufficient structure for bonding
198
Q

Failure of CEREC inlays/onlays mostly due to

A

fracture

199
Q

Which has better longevity (ceramic/gold) inlays/onlays

A

gold

200
Q

Porcelain laminate veneers have a (high/low) failure rate

A

low

201
Q

Predisposing factors for the occurance of fractures were

A
  • Partial adhesion to dentin surface
  • Presence of large composite restoration
  • Bonding endo teeth with large defects
  • Heavy parafunction/loading
202
Q

Thickness of the luting composite for inlays and onlays must not exceed what ratio

A

1:3 to ceramic thickness

203
Q

Microleagae is more pronounced when the prep margin is in (enamel/ dentin )

A

dentin

204
Q

Microleakage in inlays and onlays is influenced by

A
  • Location of prep margins (enamel>dentin)
  • type of luting agent
  • termal expansion coefficient
  • Amount of polymerization shrinkage
205
Q

Luting agent with (higher/lower) filler will minimize forces contributing to microleakage

A

higher

206
Q

Debonding is more likely to occur under what circumstances and less likely to occur when

A

more likely when 80% or more of the tooth is dentin and less likely when minimal of 0.5 mm of enamel remains peripherally

207
Q

The resin cement tooth interface is normally durable when

A

the prep was done correctly

208
Q

T/F Marginal accuracies between ACC and PFM are similar

A

t

209
Q

What type of cements enhance fracture resistance of all ceramic restorations

A

dentin bonding and resin cements

210
Q

Primary location of fracture in ACC bridge is

A

between the retainer and pontic

211
Q

What are the three step for crown try in

A
  • pre-op evaluation
  • seating on tooth
  • evaluation of seated crown
212
Q

Why should you check the crown on the die before bringing the patient in

A

-problems involing marginal fit, esthetics and articulation can be anticipated

213
Q

What should you look for when the crown is on the die

A

look for

  • Die damage
  • Intaglio surface of crown for defects
  • Marginal fit
  • Contacts
214
Q

T/F Most often for crown try in LA should be used

A

f

215
Q

Advantages of not using LA for crown cementation

A

-Pt tactile senses aren’t impaired (helpful to adjust bite and proximal contacts)

216
Q

What are the reasons a crown may not seat on the tooth

A
  • temporary cement left behind
  • tight proximal contacts
  • Over extended margin
  • intaglio surface nodules
217
Q

Areas where the intalgio surface of the crown is binding are represented on metal are

A

burnish marks

218
Q

Products you can use to see where the intaglio surface of a crown is binding

A
  • disclosing wax

- aerosol sprats

219
Q

What are the causes of excessively tight proximal contacts

A
  • imprecise die location

- abrasion of adjacent stone contact points

220
Q

Excessively tight contacts may be observed on the die if what happesns

A

displacement of the dies when the crown is seated on working cast

221
Q

What is the cause of casting blebs on the intalgio surface

A

air bubbles trapped during investment

222
Q

Overextended crown margins may be caused by

A
  • Poor impression
  • Poor die trimming
  • Surplus of untrimmed wax or porcelain.
223
Q

Cause of underextended margins

A
  • Finish line chipped (careless handling)
  • Difficulty identifying finish line
  • Poor die trimming
224
Q

Over-extended margins should be trimed from where

A

the axial surface

225
Q

What should you do if the margin is under-extended

A

request remake or take a new impression

226
Q

If you can’t get the crown to seat and you can’t figure out the reason, the most likely cause is

A

impression distortion

227
Q

A loose fitting crown may be mistaken for

A

rocking (result of binding)

228
Q

T/F tightly fitting crowns confer greater retention after cementation compared to loose crowns

A

f

229
Q

Make sure the crown is fully steating before evaluating contacts, marginal fits, etc

A

ok

230
Q

Marginal opening of _ is acceptable

A

100 um

231
Q

T/F Poor fitting margins will alter local bacteria

A

t

232
Q

T/F Under-contoured crown margins can be fixed without a crown remake

A

f- over-contoured can though if you have acess

233
Q

What should be done with the margins for gold restorations before cementation and why

A

margins should be burnished because the set cement will likely crack

234
Q

T/F burnishing margins of gold restorations improves their longevity

A

f

235
Q

How is burnishing margins done

A

dragging gold between the crown and tooth with rotarty instruments (green stone or finishing bur)
-If only minimal burnishing is needed- can use a hallenback carver

236
Q

What is the last assessment before cementation

A

occlusion

237
Q

Shim stock is how thick?

A

10 um

238
Q

Thicker articulating paper has what issues

A
  • false marks

- alters patient’s position of closure

239
Q

T/F With posterior teeth both the restoration and adjacent teeth should hold shim stock firmly in ICP

A

t

240
Q

Listening to the bite can help ID discrepancies

A

ok

241
Q

When might you need to adjust the occlusion on the tooth opposing the restoration

A

to avoid perforating the crown

242
Q

What is used to detect vulnerable areas on the crown for perforation

A

Svensen Gauge

243
Q

Why must you polish the restoration before cementation

A

wear against opposing tooth (esp. porcelain)

244
Q

What are the three retention mechanisms for restorations secured by cements

A
  • Chemical
  • Mechanical (friction)
  • Micromechanical
245
Q

Acceptable dental cements need to fulfill what criteria

A
  • Resistance to dissolution in oral environment
  • Strong bond
  • High strength under tension
  • Easy to work with
  • Biologic acceptability
  • Acceptable working and setting times
246
Q

What is the most popular type of cement

A

zinc phosphate- despite its disadvantages

247
Q

Disadvantages of zinc phosphate cements are

A

solubility

lack of adhesion

248
Q

What types of cements are commonly used for esthetic restorations

A

resin based

249
Q

The retention of a restoration cemented with zinc phosphate largely depends on what factor

A

geometric form of the tooth (limits path of displacement) AKA retention and resistance form of the prep

250
Q

What is the characteristic unique to zinc phosphate cements and what does it mean

A

filtration phenomenon which is when the liquid (phosphoric acid) seggregates from the particle

251
Q

Why is filtration phenomenon an issue, how can we prevent this

A

hazard to pulp, prevent by placing a layer of copal varnish before luting with zinc phosphate cement

252
Q

Disadvantages of zinc phosphate

A
  • Biologic effects (pulp irritation)
  • Lack of anti-bacterial agent
  • lack of adhesion
  • elevated solubility in oral fluids
253
Q

Zinc phosphate is used to cement what types of restorations

A
  • Metal
  • MCC bridges
  • cast posts
  • Some all ceramic (Procera and In-ceram) <
254
Q

Look at the screen shot table on desktop

A

ok

255
Q

Advantages of GI cements

A
  • Physicochemical bonding to tooth structure
  • Long term fluoride release
  • Low coefficients of thermal expansion
256
Q

Where in the mouth should GI cements NOT be used

A

high stress bearing areas due to low mechanical strength

257
Q

T/F If a material can set by an acid-base reaction without light curing it is an RMGI

A

t

258
Q

Material that sets via acid-base reaction that requires light cure is called

A

compomer

259
Q

Fuji plus is an example of

A

RMGI

260
Q

Advantage of RMGIs include

A
  • Dual cure
  • Fluoride release
  • Higher flextural strength than GI
  • Capable of bonding to composite
261
Q

Disadvantages of RMGI cements

A
  • Weak bond strength to tooth (enamel > Dentin)

- Absorbs water (swelling and cement weakening)

262
Q

Bonding for RMGI works how

A

-occurs to the mineral phase of the tooth via chelation of calcium ions at the surface of hydroxyapatite.

263
Q

What is the only material that is self-adhesive to the tooth without surface prep

A

GI

264
Q

Pretreatment for tooth for GI is with

A

polyalkenoic acid (improved bond strength and sealing by removing the smear layer)

265
Q

Resin cements can bond to both

A

the tooth and the restoration

266
Q

What are the three different cure options that resin cements come in

A
  • light cure
  • auto-cure
  • dual cure
267
Q

Light cure resin cements offer what advantages

A

longer working time
set on demand
improved color stability

268
Q

Variolink is a _ cure resin cement

A

dual

269
Q

Dual-cure resin cements are indicated where

A

-material opacity may inhibit sufficient light energy reaching the cement may be sufficient to begin polymerization

Fixed Midterm Spring (9 decks)

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