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Flashcards in Operative2 Deck (94):
1

UV light curing systems are no longer used and that is because dual-cure systems fixed the problem of "incomplete curing."
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct

both the statement and the reason are correct but not related (visible light-cured composites had many advantages over UV light-cured composites)

2

what is the initiator in light cure composites which absorbs energy from a visible (474 nm-blue light) light source?

The alpha-diketone

3

The minimum acceptable level for visible curing light outputs is ?

300 mW/cm2

4

All of the following statements are true concerning posterior composite restorations EXCEPT one. Which one is the EXCEPTION?
• posterior composite restorations are frequently indicated in the treatment of occlusal lesions that allow conservative preparations
• posterior composite restorations are contraindicated in a patient with heavy occlusion (bruxism)
• posterior composites are contraindicated in patients with high caries risk
• posterior composite restorations may be indicated for the restoration of Class II cavities in premolar teeth where the appearance is very important, the cavity margins are in the enamel, and the occlusal contacts are on the enamel
• posterior composites are contraindicated for cusp replacements unless a dry operating field is maintained

posterior composites are contraindicated for cusp replacements unless a dry operating field is maintained

5

The most serious limitation of the visible light-cured posterior composite restoration is ?, which can cause internal stresses and gap formations at butt-joint interfaces, which are seen at the gingival floor of Class II and V restorations

the polymerization shrinkage

6

? is the ratio between bonded and unbonded surfaces; an increase in this ratio results in increased polymerization stress. Three-dimensional cavity preparations (Class I) have the highest (most unfavorable) C-factor because only outer unbonded surfaces absorb stress

The C-factor (Incremental curing reduces the C-factor and, therefore, reduces the residual stress of the resulting composite restoration)

7

posterior composite restorations are contraindicated in a patient with ?.

a caries active mouth

8

For Class III composite preparations, the retentive grooves are placed along ? line angles (entirely in dentin).

the gingivoaxial and incisoaxial

9

Which property of filled resins is primarily to blame for the failure of Class II composite restorations?
• low flexural strength
• low compressive strength
• low tensile strength
• low wear resistance

low wear resistance

10

The difficulty in finishing composite resin restorations is due primarily to ?. The most desirable finished surface for composites is obtained with ?

• the softness of the resin matrix and hardness of the filler particles
• aluminum oxide disks

11

Which composite type is 70% to 77% percent filled by volume and has an average particle size ranging from 1 to 3 µm.
• microfills
• hybrids
• microhybrids
• packables
• flowables

hybrids
Microfills: are 35% to 50% filled by volume and have an average particle size ranging from 0.04 to 0.1 µm

12

Composite filler particles function to do which of the following? Select all that apply.
• reduce the coefficient of thermal expansion
• increase the tensile strength and compressive strength
• reduce the polymerization shrinkage
• increase the hardness
• improve wear resistance

• reduce the coefficient of thermal expansion
• increase the tensile strength and compressive strength
• reduce the polymerization shrinkage
• increase the hardness

13

The normal wear mechanism of the composite resins is best explained by the following events: abrasion of ?, followed by exposure of filler particles and subsequent dislodgement of these filler particles.

the matrix

14

When comparing the physical properties of filled resins to unfilled resins, all of the following are true EXCEPT one. Which one is the EXCEPTION?
• filled resins are harder
• unfilled resins have a higher coefficient of thermal expansion
• filled resins have a higher compressive strength
• unfilled resins have a lower modulus of elasticity
• filled resins have a lower tensile strength

filled resins have a lower tensile strength (they have a higher tensile strength)

15

When restoring a darker shade of composite, keep in mind the following:
• UV light is better than visible light
• you must keep the light 2 mm away or more
• you should cure for longer than normal
• darker shades have less chemical bonding

you should cure for longer than normal

16

Of the following, which ones are current monomers for composite resins? Select all that apply.
• bis-GMA
• PMMA
• UEDMA
• TEGDMA

• bis-GMA
• UEDMA
• TEGDMA

17

The main ingredient in traditional acrylic resin temporary materials for intraoral fabrication is:
• ethyl methacrylate
• isobutyl methacrylate
• bis-GMA
• ethylene imine
• methyl methacrylate

methyl methacrylate

18

Which restorative material has the lowest thermal conductivity and diffusivity?
• amalgam
• gold
• unfilled resin
• filled resin

unfilled resin (undesirable effects of the relatively high coefficient of thermal expansion, which is 7 to 8 times that of the tooth)

19

Acid etching enamel prior to placement of a composite restoration is required for all of the following reasons EXCEPT one. Which one is the EXCEPTION?
• conserves tooth structure
• reduces microleakage
• provides rnicromechanical retention
• increases esthetics

increases esthetics (the bevel is for both retention and esthetics)

20

Studies indicate that acid-etched composite resin restorations have the best initial seal (microleakage), however, over time, this weakens. (? has the best seal over time)

amalgam

21

Enamel etching is typically completed with:
• 37% phosphoric acid
• 13% phosphoric acid
• 37% hydrochloric acid
• 13% hydrochloric acid

37% phosphoric acid (for 15 seconds and with a 15-second rinse and a 15-second drying)

22

Little correlation exists between resin tag length and ? strength.

enamel/resin bond

23

comparison of liquid etchants and gel etchants?

Although liquid etchants produce a more uniform etch and a greater number of tags than do gel etchants, no difference in bond strength has been demonstrated between the two

24

When preparing a Class V composite preparation, you can have ? rounded internal line angles because it is ? to compress composite into them than amalgam.
• more, easier
• less, harder
• more, harder
• less, easier

more, easier

25

Which one of the following is the most important event for dentin bonding?
• smear layer removal
• smear plug removal
• peritubular dentin decalcification
• intertubular dentin decalcification

intertubular dentin decalcification

26

A gold onlay you placed last week fails. Which of the following reasons is most likely responsible for the failure?
• you "capped" the functional cusp
• you "shoed" the functional cusp
• you "capped" the nonfunctional cusp
• you "shoed" the nonfunctional cusp

you "shoed" the functional cusp ("Shoeing" is never indicated on functional cusps)

27

Rapid cooling (by immersion in water) of a dental casting from the high temperature at which it has been shaped is referred to as:
• annealing
• tempering
• quenching
• none of the above

quenching (it maintains its malleability and ductility, the investment becomes soft and granular, and the casting is more easily cleaned)

28

The set of 3 processes (annealing, hardening and tempering) is collectively known as ?
• Annealing is ? of a metal by controlled heating and cooling to make its manipulation easier.
• Tempering is ? something by heat treatment

• "heat treating"
• the softening
• hardening

29

Which of the following situations defines an Indication for a Class II gold inlay?
• a young patient with high caries rate
• a patient with little money to invest in dental work
• a patient very concerned about esthetics
• a patient with a large lesion, buccal-lingually
• a patient with low caries rate but a history of periodontal problems

a patient with low caries rate but a history of periodontal problems

30

for gold inlay, if cavity width exceeds ? the intercuspal width, the tooth should receive cuspal coverage

one-third

31

Gold alloys ? upon solidification in the investment. This needs to be compensated for by an equal amount of ? of the mold.
• shrink, expansion
• expand, shrinkage
• shrink, shrinkage
• expand, expansion

shrink, expansion

32

The dimensional compensation necessary is accomplished by two methods of expansion:

1. Setting expansion
2. Thermal expansion
Important: Thermal expansion is the principal cause for mold expansion

33

Variables that influence expansion:

• The older the investment is, the less expansion
• If the water/powder ratio is increased, the less expansion
• The shorter the spatulation time, the less expansion
• The longer the time between mixing and immersion in a water bath, the less expansion

34

Which of the following finishing margins is essentially a "hollow ground bevel", creating more bulk of restorative material near the margin and providing a greater cavosurface angle?
• knife edge
• beveled shoulder
• chamfer
• shoulder

chamfer

35

Which of the following allows for proper retention when preparing a tooth for a disto-occlusal Class II gold inlay?
• undercut on mesial
• undercut on buccal and lingual walls
• occlusal lock (dovetail)
• none of the above

occlusal lock (dovetail)

36

The cement's main function is for ?

marginal seal, not retention

37

A patient arrives at your office with his full gold crown in hand. He explains to you that another dentist delivered it just last week. You then examine the crown and the preparation. What is the most likely reason that the crown fell off?
• there was very little cement in the crown
• the preparation was only 4 mm high
• the preparation walls were tapered at about 15°
• the margins were jagged and undefined

the preparation walls were tapered at about 15° (taper is the main retention, 4 mm is enough, 3 mm is minimal)

38

The lab calls your office and asks if you want a particular casting done in a base or a noble metal. Which of the following responses is .appropriate?
• base, because the patient has a bad bruxing habit
• noble, because the patient has a bad bruxing habit
• base, because the patient wants a gold tooth
• noble, because the patient wants a gold tooth

base, because the patient has a bad bruxing habit (also called nonprecious metals, less resistant to corrosion, advantages are principally found only in their strength and low density)

39

Of the following, which is a correct match between the gold cast alloy component and its effect? Select all that apply.
• gold —decreases ductility and malleability
• gold—increases resistance to tarnish and corrosion
• copper hardens the alloy
• silver—color modifying

• gold—increases resistance to tarnish and corrosion
• copper hardens the alloy
• silver—color modifying
Gold actually increases ductility and malleability.

40

High-gold alloys used for cast restorations are:
• greater than 20% gold or other noble metals
• greater than 30% gold or other noble metals
• greater than 50% gold or other noble metals
• greater than 75% gold or other noble metals

greater than 75% gold or other noble metals (18 karat)

41

The following statements describe an MOD gold cast onlay preparation. Which would you have to change to ensure that the onlay will be successful?
• the mesial box has an axiopulpal line angle that is longer from facial to lingual than the axiogingival line angle
• from facial to lingual, the distal axiopulpal line angle is longer than the mesial axiopulpal line angle
• the mesial and distal axial walls converge
• the distal box has an axiopulpal line angle that is shorter from facial to lingual than the axiogingival line angle

the distal box has an axiopulpal line angle that is shorter from facial to lingual than the axiogingival line angle

42

When preparing a Class V cavity preparation for direct filling gold, you should ensure that you have all of the following EXCEPT one. Which one is the EXCEPTION?
• rounded internal line and point angles
• small retentive undercuts placed in the axio-occlusal and axio-gingival line angles
• mesial and distal walls that flare and meet the cavosurface at a 90° angle
• an axial wall that is convex and follows the external contour of the tooth 0.5 mm into dentin

rounded internal line and point angles (The retention form is attained by sharp internal line and point angles (axio-gingival and axio-occlusal).)

43

The axial wall of a Cl V is placed 0.5 mm into dentin (this will make the occlusal wall slightly deeper than the gingival wall because ?

there is a thicker layer of enamel making up the occlusal wall)

44

For any Class V prep (whether for amalgam, composite, or direct filling gold), the outline form is determined by ?

the extension of the carious lesion

45

The purpose of a sprue former is to create a passage for material to flow into the investment.
The sprue former is typically attached to a thin portion of the crown.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true

the first statement is true, the second is false

46

sprue formers smaller in diameter than approximately ? mm are contraindicated.

1.5 (the diameter of the sprue pin should be equal to or greater than the thickest portion of the pattern)

47

Dental wax patterns (i.e., inlays, onlays, crowns) should be invested as soon as possible after fabricating to minimize change in the shape caused by:
• reduced flow
• drying out of the wax
• relaxation of internal stress
• continued expansion of the wax

relaxation of internal stress

48

inlay wax ingredients:

• paraffin wax main part (40 to 60%)
• Gum dammar for smoothness
• Carnauba wax decrease the wax flow
Type C of wax is usually used

49

The refractory filler component of gypsum-bonded investments provides thermal expansion.
The thermal expansion is necessary to compensate for the allloy solidification shrinkage.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true

both statements are true (refractory filler is the main part which is 2/3, the rest is binder, 1/3, which hardens after mixing with liquid)

50

Using a thinner mix (which contains more water) of a gypsum-bonded investment will ?

decrease the setting expansion, increase the setting time, increase the porosity of the set material, and ultimately weaken the set material

51

All of the following are indications for a cast gold onlay EXCEPT one. Which one is the EXCEPTION?
• restoration of large lesions
• restoration of ideal occlusion in cases of drifting, hypo- and hyper eruption, etc.
• restoration of optimum contour and proximal contact
• restoration of brittle teeth (endodontically treated)
• restoration of a tooth as an abutment for removable prosthesis, creating ideal guiding planes, rest seats, and undercuts
• restoration of teeth to meet patient preference for gold
• restoration of a tooth with minimal ferrule, where a full-coverage crown would not have enough retention

restoration of a tooth with minimal ferrule, where a full-coverage crown would not have enough retention (a tooth is not a candidate for a full-coverage crown, it is not a candidate for an onlay. A tooth that does not have a minimum of 1.5 mm of ferrule effect will need a core buildup, crown lengthening, or both.)

52

Requirements for a good ferrule effect:

• 1.5 to 2 mm of buccal and lingual subgingival tooth structure
• 1 mm of tooth thickness after adequate preparation
• 4 mm of suprabony tooth structure

53

On delivery of your first crown, you notice that the margins are open when you attempt to seat the crown in the mouth. Which of the following should you check first?
• the occlusal contacts
• the proximal contacts
• for a void on the crown's interior
• for a nodule on the crown's interior

the proximal contacts

54

If the restoration is hyperocclusion and not adjusted, the tooth will become ?

• very cold-sensitive,
• show signs of mobility,
• there might be recession of the facial gingival tissue.

55

If a lab is getting a high occurrence of surface nodules on the castings they make, what might you suspect about their investing process?
• they are vacuum-investing
• they are hand-investing
• nothing in particular, hand- and vacuum-investing are the same thing
• none of the above

they are hand-investing

56

You are preparing tooth #19 for a MODB gold onlay and tooth #18 for a MODB amalgam restoration. Which of the following TWO statements correctly describe the difference in your preparations of the functionaI cusp?
• you will need 2.5 to 3 mm of reduction for gold
• you will need 2.5 to 3 mm of reduction for amalgam
• you will need 1.5 mm of reduction for gold
• you will need 1.5 mm of reduction for amalgam

• you will need 2.5 to 3 mm of reduction for amalgam
• you will need 1.5 mm of reduction for gold

57

the difference in preparations of the nonfunctionaI cusp for amalgam and gold?

• you will need 2mm of reduction for amalgam
• you will need 1 mm of reduction for gold

58

For metal-ceramic restorations: facial and lingual reduction is?

1.5 mm

59

The difference between tooth preparation for a metal-ceramic restoration and a porcelain jacket crown is mostly related to ?

the configuration of the finishing line or margin -- chamfer or bevel for metal-ceramic restorations and a butt joint for porcelain jacket crowns.

60

The most effective means for verifying adequate occlusal clearance is ?

a wax bite chew-in

61

The modified pen grasp is the most common instrument grasp in dentistry; this is because it allows for the greatest intricacy and delicacy of touch.
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct

both the statement and the reason are correct and related

62

? is the most powerful grasp and is most effectively used on the maxillary arch

The palm and thumb grasp

63

When attempting to remove a hard brittle material, like amalgam, you would prefer a bur with a:
• zero rake angle
• positive rake angle
• negative rake angle

negative rake angle (A rake angle is said to be negative when the rake face is ahead of the radius (from the cutting edge to the axis of the bur) speaking, soft materials, such as acrylics, are cut most effectively with positive rake angle burs)

64

The clearance angle serves to eliminate friction between the clearance face and the new tooth structure exposed by the cutting edge. The ? the clearance angle, the less friction.

greater

65

The ? angle is the angle formed between the ? face and
the ? face.
• edge, rake, clearance
• rake, edge, clearance
• clearance, rake, edge

edge, rake, clearance

66

Each bur blade has two sides:

1. The rake face (toward the direction of cutting)
2. The clearance face is the surface (side) of the blade that faces away from the direction of bur rotation.

67

For most effective cutting, a bur should be rotating rapidly ? contacting the tooth.

before

68

What is the blade width of a cutting instrument with the following formula: 10 - 85 - 8 -14
• 10 mm
• 1.0 mm
• 0.85 mm
• 0.80 mm

1.0 mm
• The first number indicates the width of the blade in tenths of a millimeter
• The second number indicates the primary cutting edge angle in centigrades
• The third number indicates the blade length in millimeters
• The fourth number indicates the blade angle in centigrades

69

? is not a major part of a hand cutting instrument. It is the working end of a noncutting instrument. It corresponds to ? of a hand cutting instrument

• The nib
• the blade

70

Chisels are used primarily to cut enamel.
Hatchets are primarily used to cut dentin.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true

the first statement is true, the second is false (both for enamel cutting)

71

the most important use of chisels and hatchets is ?

the rounding or beveling of the axiopulpal line angle of Class II preparations (very important).

72

The hoe excavator has the cutting edge of the blade perpendicular to the axis of the handle. It is commonly used in ?

Class III and V preps for direct gold

73

The angle former has the cutting edge at an angle (other than 90) to the blade. It is used for ?

sharpening line angles and is especially useful to form convenience points for gold foil preps.

74

An ordinary hatchet excavator has the cutting edge of the blade directed in the same plane of the handle and is bi-beveled. Used primarily on ?

anterior teeth for preparing retentive areas

75

A spoon excavator has a curved blade with a rounded cutting edge. It is used to remove ?

carious dentin and sometimes to carve amalgam.

76

You set down the hand piece after preparing a Class II amalgam on tooth #4. Your assistant hands you a ? so you can remove the last bit of caries, and then the ? so you can plane the facial and lingual walls of the prep.
• spoon excavator, enamel hatchet
• spoon excavator, straight chisel
• gingival margin trimmer, enamel hatchet
• gingival margin trimmer, straight chisel

spoon excavator, enamel hatchet

77

To polish a restoration, you will likely use a bur with less cutting blades. This is because a bur with less cutting blades will cut more efficiently.
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct

the statement is not correct, but the reason is correct (The greater the number of cutting blades on a bur results in less efficient cutting but a smoother surface (polishing burs are of this type)

78

There are several types of bleaching products available for use at home, which can either be dispensed by a dentist or purchased over-the-counter. Currently, only dentist-dispensed home-use tray-applied gels carry the ADA Seal of Acceptance.
• 30% carbamide peroxide
• 15% hydrogen peroxide
• 20% hydrogen peroxide
• 10% carbamide peroxide

10% carbamide peroxide (The active ingredient found in most over-the-counter at-home bleaching products is not carbamide peroxide, but instead is hydrogen peroxide)

79

From the following, choose the four zones in four-handed dentistry:
• operator zone
• assistant zone
• transfer zone
• patient zone
• static zone

• operator zone (from 8:00 to 11:00 o'clock)
• static zone (from 11:00 to 2:00 o'clock, reserved for the mobile cabinet and nitrous oxide apparatus)
• assistant zone (from 2:00 to 5:00 o'clock)
• transfer zone (form 5:00 to 8:00 o'clock)

80

the hand instrument to be transferred to the dentist is held by the assistant between ?

the thumb and the forefinger

81

Xerostomia is the most common adverse side effect of medications.
This is attributed to the cholinergic effects of many medications.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true

the first statement is true, the second is false (This is attributed to the anticholinergic effects of many medications)

82

Local anesthetics aid in reducing the flow of saliva during operative procedures by ?

reducing sensitivity and anxiety during tooth preparation

83

When restoring a Class II or Class III lesion, it is important to create properly shaped embrasures for all of the following reasons EXCEPT one. Which one is the EXCEPTION?
• create a spillway for food during mastication
• make the teeth self-cleansing
• protect the gingival tissue, while also allowing stimulation of it
• provide arch stability

provide arch stability (As long as a contact is present, regardless of proper embrasure contour, you will maintain arch stability)

84

• A ? is an area in which the mesial and distal surfaces of adjacent teeth in the same arch make contact.
• A ? is a point at which teeth of the opposing arches meet or touch in occlusion or closure

• contact area
• contact point

85

A tooth was restored 3 months ago by a new associate of yours. The patient is complaining of mobility and thermal sensitivity. You take a periapical radiograph. You could see all of the following in that radiograph to confirm your suspicions, EXCEPT one. Which one is the EXCEPTION?
• hypercementosis
• root resorption
• periodontal pockets
• alteration of the lamina dura
• widening of the periodontal ligament space

periodontal pockets (You should have suspected that the restoration was high, based mainly on the mobility factor. Occlusal trauma can still cause periodontal pocketing; however, that cannot be seen on a radiograph.)

86

When restoring the embrasures of posterior teeth, the contact should be formed slightly buccal from center.
This will create a wider facial embrasure.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true

the first statement is true, the second is false

87

Which of the following would NOT necessarily indicate the need for root canal treatment or extraction of a carious tooth?
• lingering pain over 15 seconds
• negative electric pulp test
• frank apical radiolucency
• percussion sensitivity

percussion sensitivity (needs caries control with a sedative temporary filling and occlusal adjustment)

88

On the first day in your solo private practice, you have a pulp exposure. Which of the following are favorable factors in avoiding root canal treatment? Select all that apply.
• it is a mechanical exposure of 1 mm
• the tooth had never been symptomatic
• the pulp tissue appears pink
• the hemorrhage is severe
• it is a pinpoint carious exposure

• it is a mechanical exposure of 1 mm
• the tooth had never been symptomatic
• the pulp tissue appears pink
(Direct pulp capping)

89

The ideal amount of time from placing an indirect pulp cap until reopening the tooth to remove the remaining decay is:
• 7 - 10 days
• 2 - 3 weeks
• 1 month
• 3 - 4 months
• 1 year
• never, unless the tooth becomes symptomatic there is no need for further treatment

3 - 4 months

90

A patient walks into your office for an emergency visit. He asks the receptionist for a cold glass of water and seems to be tilting his head sideways as to hold the water on one side of his mouth. Immediately, you suspect which reason for his visit?
• pulp necrosis
• reversible pulpitis
• symptomatic irreversible pulpitis
• asymptomatic apical periodontitis

symptomatic irreversible pulpitis (include lingering thermal pain, spontaneous pain)

91

Sometimes it is hard to distinguish between reversible and irreversible pulpitis, in which case ? is a conservative approach toward making the final diagnosis. If a tooth responds well to this temporary filling, then the need for root canal therapy at this time is ruled out.

caries control (the placement of a temporary filling)

92

A cold test reveals a lingering pain. You ask the patient to raise her hand until the pain subsides. The patient raises her hand for about 8 seconds. What does this data suggest?
• pulp necrosis
• symptomatic irreversible pulpitis
• reversible pulpitis
• symptomatic apical periodontitis

reversible pulpitis (the pain is not spontaneous and does not last longer than approximately 10 seconds after the stimulus is removed)

93

The most effective way to reduce injury to the pulp during tooth preparation is ?

to use adequate irrigation to avoid heating of the dentin

94

What was previously an MOD amalgam in #20 now shows that the entire lingual portion of the tooth has fractured off. You believe that the tooth is restorable with a pin-retained amalgam restoration/core. How many pins will you likely use and why?
• one, because you are missing the lingual cusp only
• two, because you are missing both the mesio- and disto-lingual line angles
• three, because you are missing the mesial, distal, and lingual walls

two, because you are missing both the mesio- and disto-lingual line angles (one pin per missing line angle, Pins weaken amalgam alloy!)