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Final Exam Flashcards

1
Q
  • *placed pin far enough that it will retain build up, but not so far that by the time you prep your build up its not encased…you may have to prepare into the pin. If you expose the pin during prep …..
A

A: THAT’S OK. YOU WANT IT ENCASED, BUT NEVERTHELESS ITS OK to prep into the pin.

When doing a build up or foundation and putting a pin in as a general rule pins but stress on teeth (internal stress)..but somesimtes we don’t have a choice…and that’s how we attach a buildup to the core. (Generally post/pin is after endo..) but sometimes its used to retian things.

  • cant be in so far that they violate vital pulp
  • putting pin at line angle is safest place
  • post can crack teeth too
  • *placed pin far enough that it will retain build up, but not so far that by the time you prep your build up its not encased…you may have to prepare into the pin. If you expose the pin during prep THAT’S OK. YOU WANT IT ENCASED, BUT NEVERTHELESS ITS OK to prep into the pin.
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2
Q

Smear layer

A
  1. After tooth preparation and the cre- ation of undercuts, glass ionomer is used to build the tooth up to ideal preparation form, if any defects are relatively small. Adhesion to dentin can be enhanced by removing some of the smear layer with a chemical agent. However, excessive removal of the smear layer is not recommended, because it could lead to pulp irritation.

commonly used ferric sulfate solution. Contact between the astringent and the prepared tooth surfaces must be minimized if the smear layer is to be maintained

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3
Q

-stained scerlotc dentin at MARGINAL areas you need to

A

get rid of it ALL the time, if near the pulp sometimes its ok to keep it

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4
Q

good or bad idea to do indirect or direct pulp cap under castings?

A
  • bad idea to do indirect or direct pulp cap under tooth that will get a crown. DDO ENDO FIRST
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5
Q

Does the prepared tooth roughness aid in retention?

A
  • the roughness of intaglio surface of crown DOES AID IN RETENTION,

BUT ROUGHNESS OF PREPARED TOOTH DOES NOT

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6
Q

What does BIS-GMA leave

A

what material leaves sticky unpolym oxy inhibt layer –BISGMA!

*note also has leastr shrinkage

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7
Q

What is suckback

A
  • suck back : gold in spure solidifies BEFORE GOLD IN CASTING, so that molten gold in casting gets suckback.
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8
Q

When you heat cristobalite what happens

A
  • When you heat cristobailite (in investments)or any quartz (silicon dioxide) it goes to a phase change..it expands as its heated…goes ALPHA TO BETA

Cristobalite
changes from the a to the b (high-temperature) form between 200°C (392°F) and 270°C (518°F); quartz transforms at 575°C (1067°F). These transition involve a change in crystal form, an accompanying change in bond angles and axis dimension, and a decreased density, producing a volume increase in the refractory components.

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9
Q

Which investment has most quartz gypsum or phosphate

A

PHOSPHATE

(because they expand even more than gypsum!) *in gypsum more powder gives more expansion, but liquid for the phosphate

The principal difference between gypsum- bonded and phosphate-bonded investments is the composition of the binder and the relatively high concentration of silica refractory material in the latter.
The addition of water (Silica) to the colloidal silica suspension increases the working time, and some expansions. With gypsum water doesn’t give more expansion but powder does.

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10
Q

At what temp is gypsum unstable in centigrade

A

650 or 1200 in farenheit

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11
Q

If you did wax up, can you change mind of putting in or out of oven?

A
  • if you did wax up, cant change your mind about putting wax in the oven. CANT KEEP GOING THROUGH CYCLES
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12
Q

Yellow color in gold brough by

A

copper

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13
Q

Heating up gold is what type of reaction.

A
  • HEATING UP IS EXOTHERMIC REACTION WITH GOLD, EVEN MORE WITH PHOSPHATE BONDED INVESTMENTS!/ with phosphate bonded the heating that sets will cause wax pattern to expand as well!
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14
Q

Gold crown dimensions

A

on molar fxn cusp reduction : 1.5mm-2mm, nonfucntion is 1-1.5mm

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15
Q

What is the reducitn for PFM occlusal

A
  • pfm covering entire occlusal is 2.0 mm at least everywhere!
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16
Q

Axial reduction for PFM at the margin is:

A
  • axial reduction for PFM at margin is 1.2-1.7mm
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17
Q

What tooth do i think will recieve more wear and tear in lifetime of the mouth?

A

( lower first molars). (missing lower first molars is common thing..if space is left you get 2nd molar drifting, super eruption from maxillary, alters curve of spee and Wilson

alters function, the molars end up picking heavy balance contacts!) so we see A LOT OF BRIDGES THAT ARE PUT IN TO RESTORE THE SPACE, better solution is to endo treat first molar, shorten it, ortho upright first molar, and then restore them so swayback bridge isn’t there. (reduce and put crown on)

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18
Q
  • if its more than 2 crowns, dont use what?
A

dont use tiny articulators. Anything that gets more complicated than 1-2 crowns you need to workin full arch semi adjustable articulator (getting facebow transfer etc)

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19
Q

Gold reductions?

A

-Gold reductions? 1.5 functional cusp reduction and bevel, non-functional is 1, bevel on non-functional is .3-.7.

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20
Q
  1. -What is the ideal minimum thickness of metal of a PFM?
A

0.3mm

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21
Q

-For a PFM crown on tooth 8, the ideal facial reduction is?

A

1.2-1.7mm

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22
Q
  1. -The ideal clearance of the area of the lingual concavity where you’re putting porcelain over the metal?
A

1.5mm

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23
Q
  1. -The ideal depth for a lingual axial chamfer for an anterior pfm is?
A

0.5-1mm

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24
Q

-What is the ideal clearance for a posterior PFM with porcelain covering the occlusal, both non and functional cusp?

A

2 mm everywhere at least

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25
Q

Resistance

A

ability of crown of getting dislodged by horizontal or oblique forces

26
Q

Retention

A

risk of crown getting dislodged in a manner parallel to insertion

27
Q

Resistance factors

A

they like haviing:

minimal taper, small diameter, long prep, compete coverage, adhesive resin

28
Q

Retention factors

A

they like having: parallel taper, large surface area, molar, rough intaglio, adhesive rein luting agent

*retention depends more on shape that cement for retention.

29
Q

2 main disadvantages f using composite as a core material

A

high thermal expansion,

moisutre absorbtion

30
Q

If you do an amalgam core buildup what should you avoid?

A

amalgam avoid COPPER!!! LOW COPPER!! (COPPER GIVES MORE EXPANSION WITH MOSITURE CONTAMINATION SO AVOID THAT)

glass ionomer doesn’t need etch, just more brittle, but does release fluoride.
- if you use amalgam for buildup in a mosit environment you def don’t want to use composite resin. (moist environment..you should dry it up) if you do amalgam avoid COPPER!!! LOW COPPER!! (COPPER GIVES MORE EXPANSION WITH MOSITURE CONTAMINATION SO AVOID THAT)

31
Q

One of he ways grooves and boxes improve resitance isby

A

subjecting additional luting agent areas to compression forces on cement.

32
Q

grooves and boxes are mainly for what?

A

resistance

33
Q

increase prep height will causes on of the following:

o INCREASES BOTH RESIS AND RETENION
o DECREASES BOTH
o INCREASE RESIST DECRE RETENTION
o OR VICE VERSA

A

INCREASES BOTH RESIS AND RETENION

34
Q

Increasesed surface will benefit what?

A

RETNETION ONLY and decrease resistance.

35
Q

C&B metabond

A

chemical bonding cement

will increase bond strength.. done after your resources for resistance and retention are lost. You should then tin palte if gold and then metabond.

36
Q

Why is close marginal adaptotion important for fixes prosthess to avoid caries?

A

Close marginal adaption is important for to avoid:

DISSOLUTION OF LUTING AGENT OVER TIME WILL HAPPEN!! MOST IMPORTANT!!

also affects fixed prosthesis to avoid caries, irritation, dentinal tubule exposure
o IF YOU HAVE A TIGHT MARGIN and use zinc phosphate it will stay ther forever. Otherwise not if loose margin.

37
Q

3 conflciting princepls of tooth preparation are

A

bio, mechanical, and esthetic

38
Q

on lingual axial chamfer of pfm the depth should be

A

.5-1mm

39
Q

thickness of metal under porcelain should be

A

.3mm

40
Q

if you get sparking with electro surgery instrument you should

A

adjust the current DOWN

41
Q

If the cutting tip drags and doesnt smoothly cut you need to

A

increase the current

42
Q

electrosurgery

A

The electrode should be passed rapidly through the tissue with a single light stroke and kept moving at all times. 8. If the tip drags, the instrument is at too low a setting, and the current should be increased. 9. If sparking is visible in the tissue, the instrument is at too high a setting, and the current should be decreased. 10. A cutting stroke should not be repeated within 5 seconds. 11. The electrode must remain free of tissue fragments. 12. The electrode must not touch any metallic restoration. Contact lasting just 0.4 second has been shown to lead to irreversible pulpal damage in dogs.23 13. The sulcus should be irrigated with hydrogen peroxide before the displacement cord is placed.

43
Q

Anticholinergics or antisilagoues are mainly contraindicated in:

A

old ppl and those with glaucoma

  • familiar with siallorea (drooling) (antisalagoues… contraindication : glaucoma and old ppl metabolisizng) Anti- cholinergics should be prescribed with caution in older adults and should not be used in any patient with heart disease. They are also contraindicated in individuals with glaucoma, because they can cause permanent blindness. The incidence of undiagnosed glaucoma in the general population is high, and
44
Q

Strong gag reflex is typically accompanied by

A
  • you fill find that a strong gag reflex is accompanied with sialloreah
    .side note : put a little salt at back of tongue for strong gag reflex.
45
Q

Liquid in IRM is

A

eugoenol : obtundant

46
Q

The principal difference between gypsum- bonded and phosphate-bonded investments is the composition of the binder and the relatively high concentration of silica refractory material in the latter.

A

remember phosphate has more silica and expands more!

47
Q

hydrocal

A

o The second form of product results when gypsum is dehydrated under pressure, and in the presence of water vapor at about 125°C
o This gypsum product is called hydrocal, and is used to make type III dental stone
o Type III dental stone is an α-hemihydrate form of calcium sulfate
o Type III stone is used in many laboratory procedures, as well as to fabricate diagnostic casts, and partial and complete dentures

48
Q

densite

A

o The third form of dental product results when gypsum mineral is boiled in a 30% calcium chloride solution
o The chloride is then washed from the rock, and the remaining mineral is ground to the desired level of fineness
o This gypsum product is called densite, and is used to make type IV and V die stones
``

49
Q

refractory material

A

: in investments the REFRACTORY MATERIAL IS THE SILICA, AND ITS HEAT RESISTANCT..THATS THE FILLER MATERIAL FOR PHOSPHATE BONDED ESSENTIALLY

50
Q

5 types of recognized gypsum are

A
  • 5 TYPES OF RECOGNIZE GYMPSUM (plaster impression, plaster model, dental stoen, dental stone high strength, dental stone high strength high expansion) 1-V
51
Q

when you quench you

A

YOU GET LESS ORDERED STRUCTURE

52
Q

metals to avoid are

A

nickel and berrylium

53
Q

what are the noble metals

A

gold, pallladium, platinum

54
Q

After bulking or coping you can

A

test stability whether pattern will draw!

55
Q

on teeth dont build on

A

posterior excursive interferences

56
Q

sprue recommendations

A

A 2.5-mm (10-gauge) sprue is recommended for molar and metal-ceramic patterns. A smaller 2.0- mm (12-gauge) sprue is adequate for premolar cast- ings and most partial-coverage restorations.

57
Q

The cristobalite and quartz are responsi- ble for____

A

The cristobalite and quartz are responsi- ble for the thermal expansion of the mold during wax elimination.

58
Q

Three types of expansion can be manipulated to obtain the desired size of casting:

A

setting, hygro- scopic, and thermal

59
Q

Bio- logic properties that can be evaluated include

A

gingival irritation, recurrent caries, plaque retention, and allergies.

60
Q

Mechanical properties include

A

wear resistance and strength, marginal fit, ceramic bond failure, connector failure, and tarnish and corrosion.

61
Q

Phosphate-bonded investment materials offer certain advantages over gypsum-bonded invest- ments.

A

They are more stable at high temperatures and thus are the material of choice for casting metal- ceramic alloys. They expand rapidly at the tempera- tures used for casting alloys, and their expansion can be conveniently and precisely controlled. The increased expansion that they exhibit results from a combination of the following factors:

fp (11 decks)

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