Brazing, soldering and Welding Flashcards
1
Q
How are all ceramic 3 unit bridges made?
A
scanning
2
Q
All metal 3-u bridges can have these types of rigid connectors:
A
1 piece, soldered joint, welded joint
3
Q
Is there mobility between retainer or pontic of all metal 3-u bridge?
A
no
4
Q
This is joining 2 pieces of metal wo addition of 3rd:
A
welding
5
Q
Thi is joining of 2 pieces of metal w the addition of 3rd
A
soldering
6
Q
Which do we use for partial dentures, soldering, brazing, or welding?
A
soldering and brazing
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
8
Q
Temp for soldering:
A
< 450C
9
Q
Temp for Brazing:
A
> 450C
10
Q
Is the temp we used above or below 450C?
A
above
11
Q
Do we say that we solder or braze in dentistry?
A
braze, even though we are in the soldering range
12
Q
Types of solder:
A
soft and hard
13
Q
MP of soft solder:
A
< 260C (low)
14
Q
Components of soft solder:
A
lead-tin alloy
15
Q
Is plumbers solder soft or hard?
A
soft
16
Q
Which solder type do we use and why?
A
hard, bc soft has lead in it
17
Q
How do we solder w hard solders?
A
torch, oven, etc. (high MP)
18
Q
Types of hard solders:
A
Gold-based, silver-based
19
Q
silver-based solders are commonly used for:
A
ortho appliances
20
Q
Gold-based solders are commonly used for:
A
crown and bridge applications
21
Q
Characteristics of gold-based solders:
A
good tarnish and corrosion
22
Q
Melts at lower temp, gold-based or silver based?
A
silver based
23
Q
Why isn’t silver based solder used in fixed?
A
they will oxide
24
Q
What is meant when we refer to the fineness of dental solder?
A
prop of pure gold/ 1000 parts of alloy
25
What determines the melting range of dental solder?
composition of solder
26
Req for dental solder:
fuse safely below sag or creep temp of casting to be soldered, resistant to tarnish and corrosion (Ag/Cu ratio), easy to flow, strong
27
What determines how resistant to tarnish dental solders are?
Ag/ Cu raito
28
Casting metal is aka:
parent metal
29
The higher the Ag/Cu ration the more/ less likely to turn green (oxidize)
higher
30
How to add flow to dental solders:
add tin
31
Which will oxidize in OC, Ag or Cu?
both
32
for fixed prosth low silver = higher/lower melting temp?
higher
33
Add this to reduce oxidation
zinc
34
Effects of adding Ag to solder:
inc flow, whiten alloy, discolor the porcelain
35
Effects of adding Cu to solder:
de flo, discolor porcelain
36
Effect of adding Sn to solder:
dec fusion temp,
37
Effects of adding Zn to solder:
dec fusion temp, oxygen scavenger
38
Props of low fineness solders:
low viscosity, generally used for joining
39
Props of high fineness solders:
high viscosity, can be used for adding contacts, resist tarnish
40
What can be used to add contacts:
high fineness solders
41
I have no idea how to read this chart, slide 6
check
42
This is the joining of components before porcelain application (high fusing alloy)
presoldering
43
What does the fusion point have to be soldering framework that will have porcelain added?
temp higher than fuin point of porcelain, lower than parent metal
44
How to send something to be soldered to the lab:
solder index
45
2 types of soldering techniques:
pre and postsoldering
46
What is postsoldering?
after porcelain application (low fusing alloy) using porcelain oven
47
Why is postoldering more difficult?
have to plan where the attachment will be
48
advantage of postsoldering:
can try in, look at contacts
49
Difference bw pre and post soldering:
Before or after porcelain application, high fusing vs. low fusing alloy
50
More accurate, 1-piece casting of 3-u bridge or brazed joints?
comparable
51
Why to braze joints of 4-5-u bridge vs. 1-piece
allows better marginal fit, otherwise significant deformation
52
Can we either do 1-piece or brazed connector for 3-u bridge?
yes, probably do 1 piece since marginal fit is usually not compromised
53
How to know if bridge needs to be soldered:
if it is rocking
54
As this increases, marginal fit of brazed joint frameworks decreases:
span
55
Which is more accurate, pre or post soldering?
same
56
Which type of soldering to use fror 4-5-u partial:
either
57
Why to minimize space between 2 parent metals when soldering:
for distortion, smaller gap: less distortion,
58
Cause of porosity when soldering:
inadequate flow, gap too small
59
Gap distance less than this will lead to greater porosity:
0.005 in (0.123mm)
60
These both result in increased strength of framework
wider gaps, overn-soldered joints
61
Oven soldered joints and wider gaps both lead to:
more distortion
62
Which is stronger, pre or post ceramic soldering?
same
63
Pre and post ceramic soldering require:
broad contact, wo compromising tissues, esp papilla for esthetics, greater sa is better, flat, not rounded, parallel, even, .25mm
64
How to maintain the BL curvature of the tooth when soldering:
DON'T! Flat
65
Does soldering accuracy inc or dec w gap width?
dec
66
Recommended gap width:
0.25mm
67
Issue w small gap width:
difficult to flow
68
How to smoothen gap surface:
stone or abrasive disk
69
Why to smoothen gap surface:
to remove surface oxides
70
What to do so solder can flow in
create lines w finishing stones should be B-L or L-B, in direction of solder flow
71
Grain structure during hardening of solder during cooling stage:
order-disorder transformation, formation of intermetallic phase
72
How to create a joint w ductility:
water quenching
73
How to create strong but brittle, luss ductile joint:
slow cooling to room temp
74
Result of immediate quenching after soldering:
warping of FDP, esp longer span
75
This removes or prevents oxides:
flux
76
Result of too much flux
get incorporated into joint, glass brittle, just enough to get the solder to flow
77
Why do we want to remove oxides?
so solder is free to wet the clean metal surface
78
Components of Borax flux:
55 parts Borax glass (Na2B4O7): 35 parts boric acid, 10 parts silica
79
Borax glass has an affinity for:
copper oxides
80
2 types of flux:
borax, fluoride
81
Fxn of F flux different that Borax:
dissolves chromium oxide (base metal)
82
All fluxes cause:
pitting, discoloration of porcelain if contacted
83
This limits the flow of solder to unintended areas:
antilux
84
Types of antiflux:
graphite or suspension of rouge (ferric oxide) or chalk (calcium carbonate) in alcohol
85
What is suspension of rouge:
ferric oxide, antiflux
86
What is calcium carbonate?
chalk, antiflux
87
Materials for soldering index:
impression plaster, ZOE paste, wax, acrylic resin (GC pattern)
88
Fxn of was during soldering indexing:
to hold impression plaster as a matrix
89
GC pattern resin is aka:
PMMA
90
Type of impression plaster to use for soldering indexing:
Type i, weak, sets quickly
91
Disadv to solder indexing:
no one verifying both are seated properly, pontics can tilt abutments + open margin
92
Parts of soldering index:
impression plaster, occlusal registration
93
Tech to use for solder indexing:
paintbrush technique
94
Solder indexing is generally done extra/ intra orally?
intra
95
When do we do postsoldering in the clinic?
never, why not if it is equally as successful as pre? check
96
Investment materials:
Quartz-based, phosphate bonded, gypsum based
97
Type of investment to use with typical low fusing gold solders;
quartz-based
98
Lowest thermally expanding form of silica:
fused silica
99
typical low fusing gold solders contain:
fused silica - lowest thermally expanding form of silica
100
Investment material to use w preceramic:
phosphate bonded
101
Which should expand more, alloy or investment?
same
102
If invest deforms you must:
section and create a new retainer
103
How to dissipate heat,
fill internal aspect, especially smaller retainer,
104
Is it more important to dissipate heat for smaller or larger retainers?
smaller
105
This helps to guid the flame, so solder flows where we want it to:
bevel in the investing stone
106
Should the margins be exposed or w/in investment when soldering?
within
107
Preheating temp or low heating solder:
650C, 1202F
108
Preheating temp for preceramic soldering:
850C, 1562F
109
Excessive heat can cause:
intermetallic layering, weak mechanical structures
110
Postceramic is always done here:
oven
111
3 brazing methods:
Torch, oven, infrared
112
Low-fusing gold, low or high heat?
low
113
Type of torch to use for low-fusing gold:
gas-air
114
Preceramic solder, low or high heat:
high
115
Type of torch to use preceramic solder:
gas-oxygen
116
Type of flame to use for low fusing gold:
brush flame
117
Type of lam to use for preceramic solder:
pinpointed
118
When to use oven soldering:
postceramic soldering or multiple solder joints
119
Area we use w torch soldering:
reducing area
120
Zones: 1-4 and relative ratio:
1: Mixing zone, 2: Combustion zone, 3: Reducing zone, 4: Oxidizing zone
121
easiest to apply pontic to the smaller or larger abutment?
larger
122
What to do immediately after indexing:
try back in mouth to see if margins ar good
123
Purpose of V shaped cut in investment material:
guide heat and flow solder
| solder
124
Direction of solder flow:
toward heat
125
Highest flame temp should be located here during soldering:
in the connector area
126
Assembly to solder;
assembly position on mesh over reducing zone of flame , another torch is then gradually half-circled from B to O to L
127
Result of not brushing torch back and forth over soldering assembly
melt parent metal
128
What happens to PMMA is you are heating:
burns out, chips away
129
Heat at the same time always for:
expansion to remain the same
130
When to place solder:
after antiflux, heat after solder is in place
131
What must happen to the solder for it to form a complete connection?
must "spin" in connector
132
don't expose this when making V:
distal margin of retainer
133
This should be done before making soldering assembly:
air abrasion
134
Why to never combine alloys during soldering:
difficult to get adequate solder joint between them
135
Should you have highest or lowest melting temperature at all steps?
highest
136
List the order of steps, highest req temp to lowest:
Casting MCC framwork, preceramic brazing, porcelain application, CCC casting, postceramic brazing, CCC brazing
