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indirect Restoration > Brazing, soldering and Welding > Flashcards

Brazing, soldering and Welding Flashcards

1
Q

How are all ceramic 3 unit bridges made?

A

scanning

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2
Q

All metal 3-u bridges can have these types of rigid connectors:

A

1 piece, soldered joint, welded joint

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3
Q

Is there mobility between retainer or pontic of all metal 3-u bridge?

A

no

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4
Q

This is joining 2 pieces of metal wo addition of 3rd:

A

welding

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5
Q

Thi is joining of 2 pieces of metal w the addition of 3rd

A

soldering

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6
Q

Which do we use for partial dentures, soldering, brazing, or welding?

A

soldering and brazing

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7
Q

Why don’t we use welding fo fabricating partials?

A

temp needs to b too high, S and B use a 3rd metal w relatively low melting point

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8
Q

Temp for soldering:

A

< 450C

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9
Q

Temp for Brazing:

A

> 450C

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10
Q

Is the temp we used above or below 450C?

A

above

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11
Q

Do we say that we solder or braze in dentistry?

A

braze, even though we are in the soldering range

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12
Q

Types of solder:

A

soft and hard

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13
Q

MP of soft solder:

A

< 260C (low)

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14
Q

Components of soft solder:

A

lead-tin alloy

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15
Q

Is plumbers solder soft or hard?

A

soft

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16
Q

Which solder type do we use and why?

A

hard, bc soft has lead in it

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17
Q

How do we solder w hard solders?

A

torch, oven, etc. (high MP)

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18
Q

Types of hard solders:

A

Gold-based, silver-based

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19
Q

silver-based solders are commonly used for:

A

ortho appliances

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20
Q

Gold-based solders are commonly used for:

A

crown and bridge applications

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21
Q

Characteristics of gold-based solders:

A

good tarnish and corrosion

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22
Q

Melts at lower temp, gold-based or silver based?

A

silver based

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23
Q

Why isn’t silver based solder used in fixed?

A

they will oxide

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24
Q

What is meant when we refer to the fineness of dental solder?

A

prop of pure gold/ 1000 parts of alloy

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25
Q

What determines the melting range of dental solder?

A

composition of solder

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26
Q

Req for dental solder:

A

fuse safely below sag or creep temp of casting to be soldered, resistant to tarnish and corrosion (Ag/Cu ratio), easy to flow, strong

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27
Q

What determines how resistant to tarnish dental solders are?

A

Ag/ Cu raito

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28
Q

Casting metal is aka:

A

parent metal

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29
Q

The higher the Ag/Cu ration the more/ less likely to turn green (oxidize)

A

higher

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30
Q

How to add flow to dental solders:

A

add tin

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31
Q

Which will oxidize in OC, Ag or Cu?

A

both

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32
Q

for fixed prosth low silver = higher/lower melting temp?

A

higher

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33
Q

Add this to reduce oxidation

A

zinc

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34
Q

Effects of adding Ag to solder:

A

inc flow, whiten alloy, discolor the porcelain

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35
Q

Effects of adding Cu to solder:

A

de flo, discolor porcelain

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36
Q

Effect of adding Sn to solder:

A

dec fusion temp,

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37
Q

Effects of adding Zn to solder:

A

dec fusion temp, oxygen scavenger

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38
Q

Props of low fineness solders:

A

low viscosity, generally used for joining

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39
Q

Props of high fineness solders:

A

high viscosity, can be used for adding contacts, resist tarnish

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40
Q

What can be used to add contacts:

A

high fineness solders

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41
Q

I have no idea how to read this chart, slide 6

A

check

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42
Q

This is the joining of components before porcelain application (high fusing alloy)

A

presoldering

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43
Q

What does the fusion point have to be soldering framework that will have porcelain added?

A

temp higher than fuin point of porcelain, lower than parent metal

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44
Q

How to send something to be soldered to the lab:

A

solder index

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45
Q

2 types of soldering techniques:

A

pre and postsoldering

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46
Q

What is postsoldering?

A

after porcelain application (low fusing alloy) using porcelain oven

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47
Q

Why is postoldering more difficult?

A

have to plan where the attachment will be

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48
Q

advantage of postsoldering:

A

can try in, look at contacts

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49
Q

Difference bw pre and post soldering:

A

Before or after porcelain application, high fusing vs. low fusing alloy

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50
Q

More accurate, 1-piece casting of 3-u bridge or brazed joints?

A

comparable

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51
Q

Why to braze joints of 4-5-u bridge vs. 1-piece

A

allows better marginal fit, otherwise significant deformation

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52
Q

Can we either do 1-piece or brazed connector for 3-u bridge?

A

yes, probably do 1 piece since marginal fit is usually not compromised

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53
Q

How to know if bridge needs to be soldered:

A

if it is rocking

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54
Q

As this increases, marginal fit of brazed joint frameworks decreases:

A

span

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55
Q

Which is more accurate, pre or post soldering?

A

same

56
Q

Which type of soldering to use fror 4-5-u partial:

A

either

57
Q

Why to minimize space between 2 parent metals when soldering:

A

for distortion, smaller gap: less distortion,

58
Q

Cause of porosity when soldering:

A

inadequate flow, gap too small

59
Q

Gap distance less than this will lead to greater porosity:

A

0.005 in (0.123mm)

60
Q

These both result in increased strength of framework

A

wider gaps, overn-soldered joints

61
Q

Oven soldered joints and wider gaps both lead to:

A

more distortion

62
Q

Which is stronger, pre or post ceramic soldering?

A

same

63
Q

Pre and post ceramic soldering require:

A

broad contact, wo compromising tissues, esp papilla for esthetics, greater sa is better, flat, not rounded, parallel, even, .25mm

64
Q

How to maintain the BL curvature of the tooth when soldering:

A

DON’T! Flat

65
Q

Does soldering accuracy inc or dec w gap width?

A

dec

66
Q

Recommended gap width:

A

0.25mm

67
Q

Issue w small gap width:

A

difficult to flow

68
Q

How to smoothen gap surface:

A

stone or abrasive disk

69
Q

Why to smoothen gap surface:

A

to remove surface oxides

70
Q

What to do so solder can flow in

A

create lines w finishing stones should be B-L or L-B, in direction of solder flow

71
Q

Grain structure during hardening of solder during cooling stage:

A

order-disorder transformation, formation of intermetallic phase

72
Q

How to create a joint w ductility:

A

water quenching

73
Q

How to create strong but brittle, luss ductile joint:

A

slow cooling to room temp

74
Q

Result of immediate quenching after soldering:

A

warping of FDP, esp longer span

75
Q

This removes or prevents oxides:

A

flux

76
Q

Result of too much flux

A

get incorporated into joint, glass brittle, just enough to get the solder to flow

77
Q

Why do we want to remove oxides?

A

so solder is free to wet the clean metal surface

78
Q

Components of Borax flux:

A

55 parts Borax glass (Na2B4O7): 35 parts boric acid, 10 parts silica

79
Q

Borax glass has an affinity for:

A

copper oxides

80
Q

2 types of flux:

A

borax, fluoride

81
Q

Fxn of F flux different that Borax:

A

dissolves chromium oxide (base metal)

82
Q

All fluxes cause:

A

pitting, discoloration of porcelain if contacted

83
Q

This limits the flow of solder to unintended areas:

A

antilux

84
Q

Types of antiflux:

A

graphite or suspension of rouge (ferric oxide) or chalk (calcium carbonate) in alcohol

85
Q

What is suspension of rouge:

A

ferric oxide, antiflux

86
Q

What is calcium carbonate?

A

chalk, antiflux

87
Q

Materials for soldering index:

A

impression plaster, ZOE paste, wax, acrylic resin (GC pattern)

88
Q

Fxn of was during soldering indexing:

A

to hold impression plaster as a matrix

89
Q

GC pattern resin is aka:

A

PMMA

90
Q

Type of impression plaster to use for soldering indexing:

A

Type i, weak, sets quickly

91
Q

Disadv to solder indexing:

A

no one verifying both are seated properly, pontics can tilt abutments + open margin

92
Q

Parts of soldering index:

A

impression plaster, occlusal registration

93
Q

Tech to use for solder indexing:

A

paintbrush technique

94
Q

Solder indexing is generally done extra/ intra orally?

A

intra

95
Q

When do we do postsoldering in the clinic?

A

never, why not if it is equally as successful as pre? check

96
Q

Investment materials:

A

Quartz-based, phosphate bonded, gypsum based

97
Q

Type of investment to use with typical low fusing gold solders;

A

quartz-based

98
Q

Lowest thermally expanding form of silica:

A

fused silica

99
Q

typical low fusing gold solders contain:

A

fused silica - lowest thermally expanding form of silica

100
Q

Investment material to use w preceramic:

A

phosphate bonded

101
Q

Which should expand more, alloy or investment?

A

same

102
Q

If invest deforms you must:

A

section and create a new retainer

103
Q

How to dissipate heat,

A

fill internal aspect, especially smaller retainer,

104
Q

Is it more important to dissipate heat for smaller or larger retainers?

A

smaller

105
Q

This helps to guid the flame, so solder flows where we want it to:

A

bevel in the investing stone

106
Q

Should the margins be exposed or w/in investment when soldering?

A

within

107
Q

Preheating temp or low heating solder:

A

650C, 1202F

108
Q

Preheating temp for preceramic soldering:

A

850C, 1562F

109
Q

Excessive heat can cause:

A

intermetallic layering, weak mechanical structures

110
Q

Postceramic is always done here:

A

oven

111
Q

3 brazing methods:

A

Torch, oven, infrared

112
Q

Low-fusing gold, low or high heat?

A

low

113
Q

Type of torch to use for low-fusing gold:

A

gas-air

114
Q

Preceramic solder, low or high heat:

A

high

115
Q

Type of torch to use preceramic solder:

A

gas-oxygen

116
Q

Type of flame to use for low fusing gold:

A

brush flame

117
Q

Type of lam to use for preceramic solder:

A

pinpointed

118
Q

When to use oven soldering:

A

postceramic soldering or multiple solder joints

119
Q

Area we use w torch soldering:

A

reducing area

120
Q

Zones: 1-4 and relative ratio:

A

1: Mixing zone, 2: Combustion zone, 3: Reducing zone, 4: Oxidizing zone

121
Q

easiest to apply pontic to the smaller or larger abutment?

A

larger

122
Q

What to do immediately after indexing:

A

try back in mouth to see if margins ar good

123
Q

Purpose of V shaped cut in investment material:

A

guide heat and flow solder

solder

124
Q

Direction of solder flow:

A

toward heat

125
Q

Highest flame temp should be located here during soldering:

A

in the connector area

126
Q

Assembly to solder;

A

assembly position on mesh over reducing zone of flame , another torch is then gradually half-circled from B to O to L

127
Q

Result of not brushing torch back and forth over soldering assembly

A

melt parent metal

128
Q

What happens to PMMA is you are heating:

A

burns out, chips away

129
Q

Heat at the same time always for:

A

expansion to remain the same

130
Q

When to place solder:

A

after antiflux, heat after solder is in place

131
Q

What must happen to the solder for it to form a complete connection?

A

must “spin” in connector

132
Q

don’t expose this when making V:

A

distal margin of retainer

133
Q

This should be done before making soldering assembly:

A

air abrasion

134
Q

Why to never combine alloys during soldering:

A

difficult to get adequate solder joint between them

135
Q

Should you have highest or lowest melting temperature at all steps?

A

highest

136
Q

List the order of steps, highest req temp to lowest:

A

Casting MCC framwork, preceramic brazing, porcelain application, CCC casting, postceramic brazing, CCC brazing

indirect Restoration (54 decks)

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