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Operative 2 final > Week 4- restorative instruments > Flashcards

Week 4- restorative instruments Flashcards

1
Q

two types of powered rotary instruments

A

air-driven systems

electric-driven systems

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2
Q

advantages of air driven systems

A

cheaper to start up, replace, weigh less

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3
Q

advantages of electric driven systems

A

quieter
high torque with little stalling
smoother cut
more attachments for burs

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4
Q

three rotary speed ranges

A

slow speed

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5
Q

true/false: carbide burs are more easy to break in slow speed hand pieces?

A

true

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6
Q

advantages of high speed handpiece

A 
diamond/carbide burs remove tooth sx faster, less pressure
reduced # of cutting instruments
operator has better control
instruments last longer
less vibrations for patient
several teeth in same arch in same visit
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7
Q

true/false: most handpieces need oiling after sterilization

A

true

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8
Q

laser equipment used for:

A

tx of soft tissues and modification of hard tooth structures

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9
Q

disadvantages of laser equipment:

A

expensive
do not create good margin
hard to use
do not remove existing restorations

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10
Q

this equipment is good for stain removal and debriding pits/fissures before sealant application

A

contemporary air abrasion equipment

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11
Q

how does contemporary air abrasion equipment work?

A

uses transfer of energy from stream of powder particles from surface of tooth/restoration to produce fractured surface layer -> roughness for bonding

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12
Q

true/false: steel burs can be used in high speed handpieces?

A

false; will bend…can only be used in slow speed

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13
Q

fits into handpiece and provides bearing surface for control

A

shank

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14
Q

connects head to shank

A

neck

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15
Q

working part of rotary instrument that has cutting edge

A

head

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16
Q

carbide is stiffer than steel but has one disadvantage

A

more brittle

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17
Q

round bur used for:

A

initial entry into tooth
extension of prep
prep retention features

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18
Q

inverted cone bur used for:

A

provide undercuts in preps

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19
Q

pear shaped bur used for:

A

tooth preps for amalgam

20
Q

straight fissure bur used for:

A

amalgam preps, indirect restorations

21
Q

trends in bur design

A

less use of crosscuts (notches in blade to increase cutting efficiency)
extended heads of fissure burs
rounding of sharp tip angles

22
Q

true/false: the more blades on the bur, the smoother the cutting at slow speeds?

A

true

23
Q

number of blades on a bur is always _____

A

even

24
Q

concentricity

A

direct measurement of bur head symmetry, determines if there is a blade longer than others

25
Q

runout

A

test measuring accuracy with which all blade tips pass thru single point when instrument rotated (cannot be LESS than concentricity)

26
Q

most important design characteristic of bur

A

rake angle

27
Q

rake angle

A

angle between rake face and radius of bur

should be negative

28
Q

negative rake angle

A

rake face in front of radius of bur

minimize fractures and increase tool longevity

29
Q

rake face

A

side of blade toward direction of cutting

30
Q

clearance face

A

side of blade away from direction of cutting

31
Q

edge angle

A

angle between rake face and clearance face

larger = more tool longevity

32
Q

clearance angle

A

angle btw tooth structure and clearance face

smaller = higher edge angle = longevity

33
Q

true/false: cutting effectiveness takes into account heat or noise

A

false

just measures rate of tooth structure removal

34
Q

cutting efficiency

A

% of energy actually producing cutting

35
Q

true/false: cutting efficiency reduced when energy is wasted as heat or noise?

A

true

36
Q

abrasive cutting often leads to:

A

plastic deformation

37
Q

brittle fracture often results from:

A

high speed cutting

38
Q

diamond abrasive instruments composed of:

A

abrasive instruments held in matrix of softer material

39
Q

where does cutting occur in diamond abrasive instruments?

A

numerous places where hard particles protrude from matrix

40
Q

true/false: diamond abrasive materials not good for cutting dentin/enamel?

A

false

41
Q

diamond instrument parts:

A

metal blank (bur without blades)
powered diamond abrasive
metallic bonding material (holds diamond powder onto blank)

42
Q

why can’t you use air alone?

A

damage odontoblasts

water helps with pulp insulation

43
Q

disadvantage of air driven system

A

does not stop immediately after you stop rheostat ; careless soft tissue injury

44
Q

______ are most prone to injury of patient

A

large discs

45
Q

how to avoid third degree burns when cutting?

A

sharp burs that don’t require extreme high speeds to cut

Operative 2 final (8 decks)

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