All Readings Flashcards
(269 cards)
1
Q
Goal of management of gingival tissues is to
A
maintain the normal appearance of healthy gingiva
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
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 )
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
5
Q
Before attempting tissue displacement the characteristics of the gingiva should be as follows
A
- Healthy
- Firm
- Non-bleeding
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
7
Q
What are the two types of trauma the gingiva are exposed to during gingival displacement
A
- Mechanical
- Chemical
8
Q
Describe the trauma to the gingival tissues caused by chemicals
A
Cords + astringents are cytotoxic to gingival fibroblasts
9
Q
T/F the injury inflicted by displacement cords is irreversible and progressive
A
F- it is reversible and self-limiting
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)
11
Q
People that require gingival displacement typically have the margins _-_mm subgingivally
A
0.5-1 mm
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
13
Q
When choosing the displacement technique what should be the factor to consider
A
the type of tissue being manipulated
14
Q
What are the two biotypes of tissues
A
- Thick, flat biotype
- Thin and scalloped biotype
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
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
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
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)
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
20
Q
The distance between the CEJ and bone in thin scalloped biotype is typically _mm
A
4
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
22
Q
Subgingival margins in people with thin biotype should be avoided because
A
will likely cause additional recession
23
Q
The epithelial attachment is a zone of attachment that contains
A
JE
24
Q
T/F Epithelium doesn’t regenerate after surgery
A
f
25
Epithelial attachment is connected to (enamel/dentin/cementum) via _
enamel and cementum via hemidesmosomes
26
Restorations shouldnt extend beyond _-_mm into the gingival sulcus
0.5-1
27
_mm sarftey zone between the crest of the alveolar ridge and the margin of the crown should be maintained
3mm
28
T/F It is not possible to detect clinically where the sulcus ends and the JE begins
t
29
Consequences of invading biologic width are
marginal and papillary gingivitis which can lead to chronic inflammation and progress to periodontitis
30
The amount of pressure generated by displacement cords is significantly (higher/lower) than cordless displacement
higher
31
Consequences of heavy forces when placing displacement cords are
- Gingival recession
| - Loss of attachment
32
Clinicians are more likely to apply greater force when placing displacement cords under what circumstances
when the patient is anesthatized
33
T/F It is important to not leave the cords in the suclus for too long
t
34
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
t
35
The amount of time needed for cords to remain in sulcus is
5 mins (1-30 min)
36
Cords must remain in the sulcus for a min. of 4 mins to provide
sufficient crevicular width expansion
37
T/F long term damage to periodontium is seen when short placement times of cords are used
f
38
T/F displacement cords cause destruction of the JE
t
39
How long does it take for JE to heal after placement of displacement cords
5-14 days
40
What is the most popular method of tissue displacement
displacement cords
41
Primary cords used are
Braided and Knitted
42
Issues with cords dispensed from a container are
cross contamination
43
Which type of cord is easier to pack/place and why
braided because it has a consistent tight weave making them resistant to separation during placement. They don't split or tear during placement
44
Braided cords must be placed with (smooth/serrated) instruments contrary to knitted where you must use (smooth/serrated)
Both... smooth (non-serrated)
45
Placing the cord should start where along the tooth
interpoximally
46
What cords are able to expand when wet
knitted
47
When placing a cord in thin biotype gingiva with minimal sulcus depth the instrument of choice is
perio probe
48
Most prosthodontists soak their cords in what astringent
Aluminum chloride
49
Epinephrine in cord displacement is known to cause
- Adverse CV problems (HTN, and increased HR)
- Increased respiratory rate
- Tachycardia
- Rare (death)
50
There is about _x more epi in 1 inch of displacement cord than _
50x... 1 carpule of 1:100,000 epi
51
Describe how epi can lead to a less than idea gingival response for some patients
Epi can expose underlying CT and setup a wound-healing response
52
T/F Epi should be avoided for tissue displacement
T- esp in patients with CV issues
53
(T/F) In an experiement looking at aluminum sulfate and epi the clinician couldn't tell the difference
T
54
Composition of astringents
metal salts
55
Describe the mechanism of astringents
- Contraction of gingival tissue by contraction of BVs
| - Makes the tissue tougher (decreases exudation)
56
Extended contact between gingiva and astringents can lead to
delayed healing or tissue damage
57
Astringents are (acidic/basic) and remove the_
acidic... smear layer
58
Removing the smear layer by the astringents has what consequences
post-op sensitivity
| affects the bonding mechanism of adhesive cements
59
Hemostatic agents are available in what forms
- Liquid
- Gels
- Pastes
- Foam
60
Conc. of AC (aluminum chloride) is most commonly
20-25%
61
Buffered AC was introduced to...
prevent irritation of gingiva
62
T/F Soaking cords in astringent affects its ability to absorb fluid and expand in the sulcus
f
63
T/F There is evidence to suggest that hemostatic agents inhibit the setting of PVS
F- but there is conflicting data
64
Interference in the quality of surface detail of PVS by hemostatic agents is primarily due to
sulfur (esp in ferric sulfate)
65
What is the component of ferric sulfate that leads to staining of dentin and gingival tissue
iron
66
In order to prevent FS from affecting the surface detail reproduction of PVS what must be done
rinse FS thoroughly
67
A cord impregnated with Alum can safety be left in the sulcus for as long as _ without adverse effects
20 mins
68
Unibraid cords are preimpregnated with
10% Alum
69
Cordless displacement materials (CDM) are available in what forms
pastes, foams, gels
70
CDM contains what conc. of what active ingredient
15% AC (cluminum chloride)
71
High conc. of AC is considered >_%
10
72
High conc. AC can cause
local tissue damage
Transient ischemia
tooth sensitivity
73
Which are less traumatic to gingival tissues (displacement cords/CDM)
CDM
74
Advantages of CDM are
- Less tissue trauma compared to displacement cords
- Less painfull
- Quicker to deliver
75
CDM is preferred for tissue displacement when
- Around cement-retained implant prosethsis
| - CAD CAM
76
Indications for single cord technique
- 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
77
In the single cord technique the cord can be either removed or left in place if...
the finishline is completely visible
78
If the tissue collapses over the finishline and a good impression can't be obtained what is recommended
Electrosurgery (ES)
| Soft tissue laser
79
Double cord technique indicated for
- Single or multiple abutments
- Subgingival margin
- First cord doesn't maintain lateral tissue displacement
80
(T/F) Double cord technique --> more trauma than single cord
T
81
In double cord technique which cord is presoaked and which is impregnated
```
presoaked= 1st
impregnated= second
```
82
First cord in double cord technique is left in the sulcus during the impression to...
- Control bleeding
- Prevent collapse of tissue
- Reduce tearing of impresison material
83
Desication of the cords and the tissues leads to
- Increased chance of bleeding upon cord removal
| - Adherence of impression material to first cord --> increased changes of impression tearing
84
Electrosurgeryis also referred to as
Dilation or troughing
85
ES is mostly used to
- 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
86
ES is contraindicated in patients with
- Pacemakers
- Implanted cardioverter defibrilators
- Esthetic regions (unpredictable healing)
87
Soft tissues return to normal apparance after ES after
7-10 days
88
T.F Some Gingival height is lost after ES
t- VERY insignificant (0.5-1 mm)
89
Most painful areas after ES are
Palatal of maxillary anteriors and third molars
90
What is recommended for post-op ES pain
OTC analgesics
91
T/F results after rotary curettage for gingival displacement are predictable
f
92
What lasers are most commonly used for tissue displacement and why
diode because of their low wavelength (infrared spectrum)
93
Overextended provisionals can lead to
a periodontal lesion
94
Indirectly fabricated provisionals yeilds (better/worse) marginal adaptation over direct fabrication
better
95
Advantages of indirectly fabricated provisionals are
- 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
96
Disadvantage for indirect provisionals
- Fee for pt
| - lab steps
97
The marginal precision od a dental restoration on average is _um
50
98
T/F Intra-oral scanners for CAD CAM technology are now available and replace the need for a impression
t- but they are very expensive- not accessible to all dentists yet
99
Without an intra-oral scanner can you still mill a crown with CAD CAM
yes- need an impression though (scan the gypsum model)
100
Level of hydrophobicity of PVS was reduced how
addition of surfactants
101
PVS is most well know for
dimensional stability
| -Great elastic recovery even in climates with varying moisture, temperature, and over time
102
Impression material ideal properties are
- Dimensional stability
- Accurate
- Elastic recovery
- Tear resistance
- Sets in reasonable amount of time
- Biocompatible
- Hypoallergenic and non-toxic
103
According to the ADA elastomeric impression materials must be able to reproduce details of _um of less
25
104
PVS materials can reproduce details as small as
1-2 um
105
The (higher/lower) the viscosity the better it records fine details
lower
106
Putty materials are required only to record details of _u m
75
107
Define elastic recovery
Ability of material to return to original dimensions without significant distortion upon removal from mouth
108
For all impression materials the greater the depth of the undercut the (more/less) significant the distortion
more
109
Minimum thickness of material in tray should be a _-_ times more than the largest undercut
3-4
110
What should be done to maximize the elastic recovery of the impression
block out undercuts
111
What material has the best elastic recovery? Rank them all from best to worst
pvs (over 99%) > polyethers> polysulfides
112
PVS elastic recovery is best when... compare this to polyethers
PVS- best immediately after mixing
| Polyether= remains plastic long after mixing
113
Define dimensional stability
ability fo material to maintain accuracy over time (pour at convenience of operator)
114
Rank the impression materials from best to worst dimensional stability
PVS (addition silicone)> Polyether> Polysulfide> condensation silicone
115
For max. accuracy it is suggested to pour a polyether impression _ after removal from mouth
1 hr
116
Condensation silicone, polysulfide should be poured _ after removal from mouth
30 min
117
What are the volatile endproducts of condensation silicone and polysulfide
ethyl alcohol and water respectively
118
Significance of the volatile en-products
reason for poor dimensional stability of these impresison materials
119
Hydrophilic nature of impression material relates to its ability to
flow better in moist areas and subgingivally with more accuracy
120
More hydrophilic materials have what advantages
- Less air bubble trappying
| - Higher precision (esp. subgingivally)
121
Addition of _ increases the hydrophilicity of PVS which does what
surfactants... improves wettability and reduces contact angles... impression is more accurate and easier to pour
122
Hydrophilic impression materials are more prone to what issues
-mositure absorption --> issues with dimensional accuracy (hence why there is no perfect impression material)
123
Rheological properties means
flow characteristics
124
Impression materials must be able to flow into spaces as small as _-_um
20-70
125
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
thixotropic
126
Advantage of flexible impression materials
easier to retrieve from mouth and more forgiving with undercuts and easier to retrieve gypsum cast
127
Most rigid impression material is _ leas is _
```
most= polyether
least= alginate
```
128
Polyether due to the rigidity are not indicated for
-Thin preps on periodontally involved teeth
129
Define thixotropy
When a material has a high rate of flow under pressure but not under gravity
130
Main difference between the viscosities of the impression materials are
amount of inert filler in the material
131
Lower viscosity impression material gives better fine detail replication but has...
more polymerization shrinkage- thus want to use as little low viscosity material as needed
132
PVS and polyether may react with
remnants of hydrogen peroxide
133
T/F Metal salts (in astringents) may inhibit PVS and polyether setting
t
134
In addition to metal salts what else may inhibit setting of impression material
methacrylate composites (in core build ups, temps, etc)
135
Removal of methacrylate composites is done with
alcohol follwoed by water then dried
136
Custom trays made of PMMA (auto-cure) must rest _ long to ensure end of shrinkage
12 hrs
137
What impression materials are affected by latex
PVS only
138
Example of polyether impression material is
impregum
139
polyethers are (midly/moderately/significantly) hydrophilic
moderately
140
T/F Polyether enables multiple pours of accurate casts for 1-2 weeks
t
141
Rigidity of polyether is a disadvantage when
- Fixed appliances in mouth (bridges*)
- Open gingival embrassures
- Loss of periodontal support
- Fractures gypsum casts frequently
142
Strict disinfection of polyether impressions should be done to prevent
expansion of the material
143
Disinfection of polyether impression should be done with what material and for how long
sodium hypochlorite for 10 mins
144
Setting time for polyether
10=15 mins
145
What is the most widely used impession material in dentistry
PVS (aka addition silicone)
146
Curving of PVS leads to what byproducts
H2
147
H2 scavengers for PVS are
Pt and Pd
148
PVS can be contaminated with
sulfur compounds such as latex (gloves or RD) both direct and indirect inhibition
149
PVS is best used with what material for a custom try
acrylic resin
150
Refrigeration of PVS will do what
increase the working time by about 1.5 min (will not affect the accuracy)
151
Polysulfides are also called
-Thiocols or "rubber base" or mercaptan
152
Describe the hydrophilicity of polysulfides
low to moderatly hydrophilic
153
Advantages and disadvantages of polysulfides
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
Why should polysulfide impressions be left in the mouth 5 min beyond clinical set time
elastic recovery increases as more time pases
155
Setting time for polysulfide is
LONG 12 mins
156
Polysulfide should not be disinfected longer than _ and why
10 mins avoid swelling
157
Most common use for condensation silicones
lab putty
158
Condensation silicone setting results in the evaporation of _ resulting in
alcohol ... shrinkage
159
Who introduced the first feldspathic porcelain crown
land
160
What was added to feldspathic porcelain to increase the strength
Aluminum oxide (Al2O3)
161
A bridge min. connector height of _-_ is needed for all ceramic restoration
3-4 mm from the interproximal papilla to the marginal ridge
162
Contraindications for all ceramic FDP
- Reduced interocclusal clearance (short clinical crown, deep vertical overlap, supraeruption)
- Parafunction
163
Law of beams
deflection is inversely proportional to the cube of its height
164
Failures for all ceramic FDP compared to PFM
All ceramic= fracture of porcelain
| PFM= fracture of tooth and caries
165
According to law of beams how can we reduce the possibility of failure
increase the occlusal-gingival height of the connectors to reduce bending
166
Empress 2 is off the market and was replaced with
e.max pressed and CAD
167
(T/F) Leucite can be used for 3 unit bridge in anterior/PM region
F- single unit only
168
Vital Mark II is what kind of material
feldspathic porcelain for CEREC machine
169
Describe the multi-colored ceramic block
- Designed to overcome esthetic disadvantage of monochromatic restorations
- Inner third= opaque dark base layer
- Middle third= neutral zone
- Outer third= more translucent
170
T/F Alumina based ceramics are still used today
f
171
Example of alumina based ceramic was
procera
172
What was an advantage of procera
highest strength alumina based restoration
173
Tetragonal to monoclinic transformation of zirconia leads to _-_% volume (expansion/contraction)
3-5% expansion
174
Tensile stresses causing a crack lead to transformation of what phases in zirconia
tetragonal to monoclinic
175
Increased radiopacity of zirconia improves radiographic interpretation of
- marginal integrity
- excess cement removal
- recurrent decay
176
yytrium oxide is manufactured through
CAD CAM
177
Strength of an ACC is dependent on
- Material used
- Bond strength
- Crown thickness
- Design of restoration
178
Marginal discrepancy: Range for subgingival margins= _-_um and supragingival= _-_
34-119um
2-51 um
179
What is the limit for clinically acceptable marginal discrepancy
120 um
180
Poor marginal adaptation can lead to
- cement dissolution
- microleakage
- Increased plaque retention
- secondary decay
181
CAD CAM factors that may influence marginal integrity are
- Software limitations
- Hardware limitations
- Scanning and milling equipment
- Internal cutting bur may be larger than areas of the tooth prep
182
Issues with scanning with a contact probe are
- 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
Cements that don't work will with ACC restorations are
- Zinc phosphate
- Zinc polycarboxylate
- conventional GI
184
Why are zinc phosphate, zinc polycarboxylate and GI poor cements for ACC
because they set with a acid base reaction which exacerbates the surface slows in ceramic restorations
**Non-acid base cements recommended for ACC)
185
Why is RMGI ok for ACC
because it has two mechanisms of setting (acid base and photo-/chemical curing)
186
What etching provided the best bond strength in ACC
- 5-9.5% HF acid
| - 37% phosphoric acid + silane coupling agent
187
Bond between feldspathic and tooth is achieved with
silane coupling agents in composite resins
188
Why is resin adhesive cement recommended for ACC
-Higher flexural strength (320 MPa) and better seal (less microleakage)
189
Issues with RMGI as ACC cements are
-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
T/F Margins below the CEJ result in loss of adhesion
t
191
Which transmits more light (enamel/dentin)
enamel- enamel is very translucent
192
T/F The esthetic revolution began after it was determined that mercury vapor is released from amalgam fillings
f- at same time
193
T/F No statistical difference in the measures of mercury in patients with amalgam fillings verses composite
t (no mercury toxicity linked to amalgam fillings)
194
Why does leakage of amalgam decrease with time in mouth
- Despite only reasonably close adaptation to prep walls
| - corrosion products form at the interface --> less leakage over time
195
Advantages of inlays/onlays over direct restorations
- Better marginal fit (controversial)
- better proximal contacts
- More anatomic form
- Color matching (highly esthetic)
- Less polymerization shrinkage
- Better access
- Better wear resistance (controversial)
196
Failure of inlays and onlays mostly due to
fracture and caries
197
Contraindications for inlays and onlays are
- Bruxism patients
- poor OH
- Opposing teeth with composite restorations
- Teeth with insufficient structure for bonding
198
Failure of CEREC inlays/onlays mostly due to
fracture
199
Which has better longevity (ceramic/gold) inlays/onlays
gold
200
Porcelain laminate veneers have a (high/low) failure rate
low
201
Predisposing factors for the occurance of fractures were
- Partial adhesion to dentin surface
- Presence of large composite restoration
- Bonding endo teeth with large defects
- Heavy parafunction/loading
202
Thickness of the luting composite for inlays and onlays must not exceed what ratio
1:3 to ceramic thickness
203
Microleagae is more pronounced when the prep margin is in (enamel/ dentin )
dentin
204
Microleakage in inlays and onlays is influenced by
- Location of prep margins (enamel>dentin)
- type of luting agent
- termal expansion coefficient
- Amount of polymerization shrinkage
205
Luting agent with (higher/lower) filler will minimize forces contributing to microleakage
higher
206
Debonding is more likely to occur under what circumstances and less likely to occur when
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
The resin cement tooth interface is normally durable when
the prep was done correctly
208
T/F Marginal accuracies between ACC and PFM are similar
t
209
What type of cements enhance fracture resistance of all ceramic restorations
dentin bonding and resin cements
210
Primary location of fracture in ACC bridge is
between the retainer and pontic
211
What are the three step for crown try in
- pre-op evaluation
- seating on tooth
- evaluation of seated crown
212
Why should you check the crown on the die before bringing the patient in
-problems involing marginal fit, esthetics and articulation can be anticipated
213
What should you look for when the crown is on the die
look for
- Die damage
- Intaglio surface of crown for defects
- Marginal fit
- Contacts
214
T/F Most often for crown try in LA should be used
f
215
Advantages of not using LA for crown cementation
-Pt tactile senses aren't impaired (helpful to adjust bite and proximal contacts)
216
What are the reasons a crown may not seat on the tooth
- temporary cement left behind
- tight proximal contacts
- Over extended margin
- intaglio surface nodules
217
Areas where the intalgio surface of the crown is binding are represented on metal are
burnish marks
218
Products you can use to see where the intaglio surface of a crown is binding
- disclosing wax
| - aerosol sprats
219
What are the causes of excessively tight proximal contacts
- imprecise die location
| - abrasion of adjacent stone contact points
220
Excessively tight contacts may be observed on the die if what happesns
displacement of the dies when the crown is seated on working cast
221
What is the cause of casting blebs on the intalgio surface
air bubbles trapped during investment
222
Overextended crown margins may be caused by
- Poor impression
- Poor die trimming
- Surplus of untrimmed wax or porcelain.
223
Cause of underextended margins
- Finish line chipped (careless handling)
- Difficulty identifying finish line
- Poor die trimming
224
Over-extended margins should be trimed from where
the axial surface
225
What should you do if the margin is under-extended
request remake or take a new impression
226
If you can't get the crown to seat and you can't figure out the reason, the most likely cause is
impression distortion
227
A loose fitting crown may be mistaken for
rocking (result of binding)
228
T/F tightly fitting crowns confer greater retention after cementation compared to loose crowns
f
229
Make sure the crown is fully steating before evaluating contacts, marginal fits, etc
ok
230
Marginal opening of _ is acceptable
100 um
231
T/F Poor fitting margins will alter local bacteria
t
232
T/F Under-contoured crown margins can be fixed without a crown remake
f- over-contoured can though if you have acess
233
What should be done with the margins for gold restorations before cementation and why
margins should be burnished because the set cement will likely crack
234
T/F burnishing margins of gold restorations improves their longevity
f
235
How is burnishing margins done
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
What is the last assessment before cementation
occlusion
237
Shim stock is how thick?
10 um
238
Thicker articulating paper has what issues
- false marks
| - alters patient's position of closure
239
T/F With posterior teeth both the restoration and adjacent teeth should hold shim stock firmly in ICP
t
240
Listening to the bite can help ID discrepancies
ok
241
When might you need to adjust the occlusion on the tooth opposing the restoration
to avoid perforating the crown
242
What is used to detect vulnerable areas on the crown for perforation
Svensen Gauge
243
Why must you polish the restoration before cementation
wear against opposing tooth (esp. porcelain)
244
What are the three retention mechanisms for restorations secured by cements
- Chemical
- Mechanical (friction)
- Micromechanical
245
Acceptable dental cements need to fulfill what criteria
- Resistance to dissolution in oral environment
- Strong bond
- High strength under tension
- Easy to work with
- Biologic acceptability
- Acceptable working and setting times
246
What is the most popular type of cement
zinc phosphate- despite its disadvantages
247
Disadvantages of zinc phosphate cements are
solubility
| lack of adhesion
248
What types of cements are commonly used for esthetic restorations
resin based
249
The retention of a restoration cemented with zinc phosphate largely depends on what factor
geometric form of the tooth (limits path of displacement) AKA retention and resistance form of the prep
250
What is the characteristic unique to zinc phosphate cements and what does it mean
filtration phenomenon which is when the liquid (phosphoric acid) seggregates from the particle
251
Why is filtration phenomenon an issue, how can we prevent this
hazard to pulp, prevent by placing a layer of copal varnish before luting with zinc phosphate cement
252
Disadvantages of zinc phosphate
- Biologic effects (pulp irritation)
- Lack of anti-bacterial agent
- lack of adhesion
- elevated solubility in oral fluids
253
Zinc phosphate is used to cement what types of restorations
- Metal
- MCC bridges
- cast posts
- Some all ceramic (Procera and In-ceram) <
254
Look at the screen shot table on desktop
ok
255
Advantages of GI cements
- Physicochemical bonding to tooth structure
- Long term fluoride release
- Low coefficients of thermal expansion
256
Where in the mouth should GI cements NOT be used
high stress bearing areas due to low mechanical strength
257
T/F If a material can set by an acid-base reaction without light curing it is an RMGI
t
258
Material that sets via acid-base reaction that requires light cure is called
compomer
259
Fuji plus is an example of
RMGI
260
Advantage of RMGIs include
- Dual cure
- Fluoride release
- Higher flextural strength than GI
- Capable of bonding to composite
261
Disadvantages of RMGI cements
- Weak bond strength to tooth (enamel > Dentin)
| - Absorbs water (swelling and cement weakening)
262
Bonding for RMGI works how
-occurs to the mineral phase of the tooth via chelation of calcium ions at the surface of hydroxyapatite.
263
What is the only material that is self-adhesive to the tooth without surface prep
GI
264
Pretreatment for tooth for GI is with
polyalkenoic acid (improved bond strength and sealing by removing the smear layer)
265
Resin cements can bond to both
the tooth and the restoration
266
What are the three different cure options that resin cements come in
- light cure
- auto-cure
- dual cure
267
Light cure resin cements offer what advantages
longer working time
set on demand
improved color stability
268
Variolink is a _ cure resin cement
dual
269
Dual-cure resin cements are indicated where
-material opacity may inhibit sufficient light energy reaching the cement may be sufficient to begin polymerization
