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Council adopts American Dental Association Specification No. 5 (Dental Casting Gold Alloy)
Council adopts American Dental Association Specification No. 5 (Dental Casting Gold Alloy)
a rd s , W a s h in g t o n , D .C .; F. H . F re e m a n , K e rr M a n u f a c t u r in g
Council on D ental Research
C o ., D e tr o it;
W . D.
K im m e l,
T h e L. D . C a u lk C o ., M i lf o r d , D e l.; G u n n a r Ryge, H e a lth The
fo llo w in g
s p e c ific a tio n
w as
re c e n tly
fo rd ,
D e n ta l
R e se arc h
S e rv ic e ,
San
(s e c re ta ry ),
C e n te r ,
F ra n c is c o ;
A m e r ic a n
a tio n , C h ic a g o ; A . R. D o c k in g
th e
C o m m o n w e a lth
D e n ta l
s p e c ific a tio n
A s s o c ia tio n
fo r
of
th e
d e n ta l
A m e r ic a n
c a s tin g
g o ld
S.
D e n ta l
a d o p te d b y th e C o u n c il on D e n ta l R e se arc h as o f f ic ia l
U.
P u b lic
J. W .
S ta n
A s s o c i
(c o n s u lt a n t ) ,
B u re a u o f D e n ta l S ta n d a rd s ,
M e lb o u r n e , A u s t r a lia ;
E. L.
D y b o w sk i
(c o n
a llo y . T h e s p e c ific a tio n is th e F é d é ra tio n D e n
s u lta n t),
t a ir e In te r n a tio n a le ( F D D
q u ire m e n ts , U . S. A i r F o rce, W a s h in g t o n , D .C .;
S p e c ific a tio n N o . 7
D e n ta l
R e së arc h
and
C lin ic a l
R e
fo r D e n ta l C a s tin g G o ld A llo y w h ic h w as f o r
P.
m u la te d
A rm y
M e d ic a l
M a t e r ia ls , I n s tru m e n ts , E q u ip m e n t a n d T h e r a
N.
Rupp
p e u tic s . T h e F D I s p e c ific a tio n w a s co n s id e re d
M e d ic a l C e n te r , N a v a l D e n ta l School, B e th -
b y th e S p e c ific a tio n s C o m m itte e o f th e D e n ta l
esda, M d .
b y th e
FDI
C o m m is s io n on
D e n ta l
M a t e r ia ls G ro u p o f th e In te r n a tio n a l A s s o c i a tio n
fo r D e n ta l
c o n s u ltin g
body
R e se arc h , w h ic h a c ts as a to
th e
C o u n c il
on
m a tte r s
p e r ta in in g to d e n ta l s p e c ific a tio n s . T h e sp ec ific a tio n s
C o m m itte e
C o u n c il t h a t th e
re c o m m e n d e d
F D I s p e c ific a tio n
to
th e
be m a d e
M. E.
M a r g e t is
( c o n s u lt a n t ) , W a l t e r C e n te r ,
W a s h in g to n ,
( c o n s u lt a n t ) ,
N a t io n a l
Reed D .C .; N aval
T h e C o u n c il als o a c k n o w le d g e s th e a s sist a n c e o f th e s u b c o m m itte e in e v a lu a tin g th e s p e c ific a tio n : N a t io n a l
G e o rg e
D ic k s o n
(c h a irm a n ),
B u re a u o f S ta n d a rd s , W a s h in g to n ,
D .C .; G. D .
B o u lg e r, W .
E. M o w r e y C o ., St.
P a u l; C . E. In g e rs o ll, W illia m s G o ld R e fin in g
a n o f f ic ia l s p e c ific a tio n o f th e A m e r ic a n D e n
C o ., B u ffa lo ;
ta l A s s o c ia tio n to re p la c e A D A
trie s , In c ., E as t N e w a r k ; J o h n S. S h e ll, H o lle n -
No.
5
C o u n c il
fo r
D e n ta l
C a s tin g
S p e c ific a tio n
G o ld
w is h e s to a c k n o w le d g e
A llo y . th e
The
h e lp
of
back W.
T.
E. 0 .
R e se arc h S w ee n e y,
L ie b ig , E n g e lh a rd
A s s o c ia te s , N a t io n a l
E n cin o ,
B u re a u
In d u s C a lif .;
o f S ta n d
th e S p e c ific a tio n s C o m m itte e w ho se m e m b e rs
a rd s , W a s h in g to n ,
a r e : F. A . P e y to n
( c h a ir m a n ) , School o f D e n
S.
t is t r y ,
of
W e s t f ie ld , N . J .; D . L. S m ith , T h e J. M . N e y
U n iv e r s ity
G e o rg e D ic k s o n ,
436
M ic h ig a n ,
N a t io n a l
Ann
A rb o r;
B u re a u o f S ta n d
S. W h i t e
C o .,
C o ., H a r t fo r d .
D .C .;
N.
0.
P h ila d e lp h ia ;
T a y lo r , T h e E. M .
W is e ,
American Dental Association Specification No. 5 for Dental Casting Gold Alloy
4. SA M P L IN G , PRO CEDURES
(Fédération Dentaire Internationale Specification No. 7 for Dental Casting Gold Alloy)
IN SPEC T IO N A N D T E S T IN G
4.1 Sampling. Twenty pennyweight of alloy shall be pro cured at retail by a member of the American Dental Asso ciation. This sample shall be forwarded in the original un opened package or packages to the American Dental Asso ciation Council on Dental Research, 211 East Chicago Avenue, Chicago, Illinois 60611. In addition, the m anu facturer shall submit six tensile specimens for Types I, II, and III, and 12 specimens for Type IV in the as-cast con dition with button, sprue and vents attached. The diameter of these specimens shall be not less than 2.0 mm. (0.079 in.) nor more than 2.5 mm. (0.098 in.). The specimens shall be not less than 9 cm. (3.5 in.) long.
Second revision, approved in April 1965. Effective April 1, 1966
I . SCO PE A N D C L A S S IF IC A T IO N
1.1 Scope. This specification covers dental casting alloys based on gold and used in the fabrication of dental restora tions and appliances (6.1) 1.2 Classification. 1.2.1 Types. Dental casting gold alloy shall be of the following types as specified: Type I. Soft Type II. Medium Type III. H ard Type IV. Extra hard
4.2 Inspection. Visual inspection shall be used in determin ing compliance with the requirements outlined in 3.1 and 5. 4.3 Chemical tests. 4.3.1 Composition. The determined values for metallic constituents (table) shall be recorded to the nearest 0.5 per cent. When a determined value is midway , between a half and a whole number, the whole num ber shall be recorded. 4.4 Physical tests. 4.4.1 Preparation of specimens. Physical properties other than fusion tem perature shall be determined on càst specimens placed in a furnace at 700 ± 10°C. (1292 ± 18°F.) for 10 minutes and quenched in water at room temperature. Hardened specimens shall be prepared by placing the quenched specimens in an oven heated to 450 ± 5°C. (842 ± 9°F.). After they have been in the oven for two minutes the tem perature shall be reduced uniformly at 7 ± 1°C . (12 ± 2 °F .) a minute to 250 ± 5°C. (482 ± 9°F.) in 30 minutes and immediately shall be quenched in water at room temperature. Cast specimens shall be prepared by casting into a dental casting investment that satisfies the requirements of 2.1, using any dental casting method. The use of a wax pattern is not required.
2. A P P L IC A B L E S P E C IF IC A T IO N S
2.1 Specification. American Dental Association Specifica tion No. 2 for Casting Investment for Dental Gold Alloy is applicable to 4.4.1. (Copies of American Dental Association specifications may be obtained upon application to the Council on Dental Research, American Dental Association, 211 E. Chicago Ave., Chicago, 111. 60611, or to the American Dental Association Research Division, National Bureau of Standards, Washington, D.C., 20234.)
3. R EQ U IR E M E N T S
4.4.2 Compliance with requirements for tensile properties and hardness specifications. An alloy complies with the tensile and hardness requirements when all of the recorded values for strength, elongation and Brinell number, of three or more of a series of six castings of each heat treatment, meet the requirements.
3.1 Color. The color of the alloy shall be the color speci fied by the purchaser. 3.2 Composition. The composition requirements shall be as given in the table. 3.3 Physical properties. The requirements for physical properties shall be as given in the table. 3.4 M anufacturer’s instructions. Instructions for softening and for hardening heat treatm ent for Type III and Type IV alloy and the melting ranges of all types shall be included in the labeling or accompanying literature.
Table 1
Type
4.4.3 Brinell number. Specimens, not less than 2 mm. (0.08 in.) long, shall be sawed from the cast tensile spec imens, m ounted and polished, using progressively finer abrasive paper ending with a no. 3/0 emery paper. The
Composition and physical properties
Gold and metals of the platinum group
Min.
Min.
Hardened
Hardened
Quenched
Max.
Elongation 5-cm. gauge length
Tensile strength
Brinell number
Min.
%
Min. kg/cm2
Min. psi
Fusion tempera ture
Quenched
Hardened
Min.
Min.
%
%
Min. °C .
°F .
1
83
40
75
_
__
__
18
—
930
1706
II
78
70
100
--
—
900
1652
78
90
--
12
—
900
1652
IV
75
130
140 —
— —
12
III
— __
200
6,350
90,316
10
870
1598
2
REPO RTS OF C O U N C IL S A N D B U R E A U S • 437
Brinell number shall be determined by applying a 15-kg. load (33-lb.) on the specimen through a hardened steel ball 1.59 mm. (0.0625 in.) in diameter for 30 seconds. The diameter of the depression shall be determined by measur ing two diameters perpendicular to each other and the average shall be used in the calculation of the hardness number. The determined value shall be recorded as the nearest whole number. When thè determined num ber falls midway between two numbers, the even num ber shall be recorded. The Brinell number shall be calculated by the following form ula:
Bn =
P ---------------- ----------it (D /2 ) (D — V D 2 -
. — d*)
Where P = Test load in kilograms D = Diameter of ball in millimeters d = diameter of impression in millimeters 4.4.4. Tensile strength. The tensile strength shall be determined on the cast specimens submitted by the m an ufacturer. The loading rate shall be 100 ± 20 kg. (220 ± 44 lb.) per minuté. The specimen shall be loaded con tinuously from the initial load to the breaking point. The strength shali be computed on the basis of the original cross-section area. 4.4.5 Elongation. Elongation shall be determined on the specimen used in the test for tensile strength. Castings that break outside the gauge m arks may be repulled. Elongation shall be measured on a 5-cm. (1.97-in.) gauge length.. The determinéd value shall be recorded as the neatest 0.5 per cent. 4.4.6 Fusion temperature. The following apparatus shall be used: An electric furnace having a tube muffle approxi mately 25.4 mm. (1 in.) in inside diameter and mounted in a vertical position; a pyrometer accurate to ± 5"C. (± 9 °F .); an ingot of gold 13 mm. (0.5 in.) by 6.4 mm. (0.25 in.) by 0.51 ± 0.13 mm. (0.020 ± 0.0Ô5 in.) with holes having a diameter of 1.6 mm. (0.062 in.) centered 2.4 mm. (0.094 in.) from either edge at the center of the 6.4 mm. (0.25 in.) dimension; one piece of 20-gauge 0.81 mm. (0.032 in.) platinum or chromium-nickel wire (chromel) and a 300-Gm. (10.6-oz.) weight. The following procedure shall be used: The tip of an alumel-chromel or platinum versus platinum-rhodium ther mocouple of 20- or 22-gauge wire 0.81 mm. (0.032 in.) or 0.64 mm. (0.0253 in.) shall be bent into an “S” shape. The loop of the “S” curve nearest the long leads of the therm o couple shall be hooked into one of the 1.6 mm. (0.062 in.) holes of the ingot. The loop of the “S” curve nearest the hot junction shall be bent so that the hot junction lies ilear the. center of the ingot. A 20-gauge chromium-nickel or platinum wire shall be passed through the hole at the opposite end of the ingot and tied. The long leads of the thermocouple shall be secured at the top of the furnace so that the ingot hangs in the center of the muffle. A 300-Gm. weight shall be at tached to the chromium-nickel or platinum wire so that the weight hangs freely below the furnace. The top of the muffle shall be covered with a suitable refractory to prevent air currents. The bottom of the muffle shall be covered with a sheet of asbestos containing a hole 6.4 mm. (0.25 in.) in diameter. The hole in the sheet shall be centered with the center of the muffle opening to permit unobstructed passage of the loaded wire. The temperature of the furnace shall be raised to within 111°C. (200°F.) of the estimated lower limit of the melting range. The temperature shall then be increased 11 ± 3°C. (20 ± 5°F.) a minute. The tem perature at which the ingot breaks under the 300-Gm. load shall be recorded as the fusion temperature. The value shall be reported as
438 • JA D A , Vol. 72, Feb. 1966
the average of tests on three specimens and shall be re corded to the nearest degree Celsius (1.8°F.) 5. PR E P A R A T IO N FOR D E L IV E R Y
5.1 Packaging. The alloy shall be packaged in accordance with acceptable commercial practice. 5.2 Marking. 5.2.1 Lot numbers. Each container shall be m arked with a serial number or combination of letters and numbers which shall refer to the m anufacturer’s records for the particular lot or batch of alloy. 5.2.2 Date of manufacture. The date of m anufacture (year and m onth) shall be indicated on the container as a separate item or as a part of the serial number (5.2.1) 5.2.3 Net weight. The weight of the contents shall be marked on each container. Individual packets of small ingots o f'fro m 1.5 to 3.0 Gm. (one to two pennyweight) may have a tolerance of minus 1.0 per cent maximum. Packets of 30 Gm. or more (one troy ounce or m ore) may have a toler ance of minus 0.1 per cent maximum. 6. N O T ES.
6.1 Uses. The four types of alloys specified are ordinarily used for the following dental restorations and appliances. 6.1.1 Type I.
Those subject to very slight stress and where burnishing is desired.
6.1.2 Type II.
Those subject to moderate stress; % crowns, abutments, pontics, full crowns and saddles.
6.1.3 Type III. Those subject to high stress; thin % Crowns* thin cast backings, abutments, pontics, full crowns and saddles. 6.1.4 Type IV. Those thin in cross section and subject to very high stress; saddles* bars, clasps, crowns, thimbles and unit castings. 6.2 References. The following references will assist the observer in testing casting gold alloys for compliance with this specification. 6.2.1 Brumfield, R. C. Tentative standard methods of test ing precious metal dental materials (Technical Committee, Dental Gold Institute). JA D A 49:17 July 1954. 6.2.2 Coleman, R. L., Jr. Physical properties of dental materials (Gold alloys and accessory materials). Res. Paper No. 32, J. Research NBS 1:867 Dec. 1928. 6.2.3 Taylor, N. <3., Paffenbarger, G. C., and Sweeney, W. T. Inlay casting golds: Physical properties and specifica tions. JADA 19:36 Jan. 1932.
Dental Dealer Sales Dental dealers closed out 1964 with an average total sales increase of 7.9 per cent over 1963 and 28.4 per cent over the 12month average of 1957-59. In the fourth quarter, dealers averaged 9 per cent higher than 1963, with December sales up 15.3 per cent over a year ago.
American Dental Trade Association, Trade Trends, Feb. 12 1965.
a rd s , W a s h in g t o n , D .C .; F. H . F re e m a n , K e rr M a n u f a c t u r in g
Council on D ental Research
C o ., D e tr o it;
W . D.
K im m e l,
T h e L. D . C a u lk C o ., M i lf o r d , D e l.; G u n n a r Ryge, H e a lth The
fo llo w in g
s p e c ific a tio n
w as
re c e n tly
fo rd ,
D e n ta l
R e se arc h
S e rv ic e ,
San
(s e c re ta ry ),
C e n te r ,
F ra n c is c o ;
A m e r ic a n
a tio n , C h ic a g o ; A . R. D o c k in g
th e
C o m m o n w e a lth
D e n ta l
s p e c ific a tio n
A s s o c ia tio n
fo r
of
th e
d e n ta l
A m e r ic a n
c a s tin g
g o ld
S.
D e n ta l
a d o p te d b y th e C o u n c il on D e n ta l R e se arc h as o f f ic ia l
U.
P u b lic
J. W .
S ta n
A s s o c i
(c o n s u lt a n t ) ,
B u re a u o f D e n ta l S ta n d a rd s ,
M e lb o u r n e , A u s t r a lia ;
E. L.
D y b o w sk i
(c o n
a llo y . T h e s p e c ific a tio n is th e F é d é ra tio n D e n
s u lta n t),
t a ir e In te r n a tio n a le ( F D D
q u ire m e n ts , U . S. A i r F o rce, W a s h in g t o n , D .C .;
S p e c ific a tio n N o . 7
D e n ta l
R e së arc h
and
C lin ic a l
R e
fo r D e n ta l C a s tin g G o ld A llo y w h ic h w as f o r
P.
m u la te d
A rm y
M e d ic a l
M a t e r ia ls , I n s tru m e n ts , E q u ip m e n t a n d T h e r a
N.
Rupp
p e u tic s . T h e F D I s p e c ific a tio n w a s co n s id e re d
M e d ic a l C e n te r , N a v a l D e n ta l School, B e th -
b y th e S p e c ific a tio n s C o m m itte e o f th e D e n ta l
esda, M d .
b y th e
FDI
C o m m is s io n on
D e n ta l
M a t e r ia ls G ro u p o f th e In te r n a tio n a l A s s o c i a tio n
fo r D e n ta l
c o n s u ltin g
body
R e se arc h , w h ic h a c ts as a to
th e
C o u n c il
on
m a tte r s
p e r ta in in g to d e n ta l s p e c ific a tio n s . T h e sp ec ific a tio n s
C o m m itte e
C o u n c il t h a t th e
re c o m m e n d e d
F D I s p e c ific a tio n
to
th e
be m a d e
M. E.
M a r g e t is
( c o n s u lt a n t ) , W a l t e r C e n te r ,
W a s h in g to n ,
( c o n s u lt a n t ) ,
N a t io n a l
Reed D .C .; N aval
T h e C o u n c il als o a c k n o w le d g e s th e a s sist a n c e o f th e s u b c o m m itte e in e v a lu a tin g th e s p e c ific a tio n : N a t io n a l
G e o rg e
D ic k s o n
(c h a irm a n ),
B u re a u o f S ta n d a rd s , W a s h in g to n ,
D .C .; G. D .
B o u lg e r, W .
E. M o w r e y C o ., St.
P a u l; C . E. In g e rs o ll, W illia m s G o ld R e fin in g
a n o f f ic ia l s p e c ific a tio n o f th e A m e r ic a n D e n
C o ., B u ffa lo ;
ta l A s s o c ia tio n to re p la c e A D A
trie s , In c ., E as t N e w a r k ; J o h n S. S h e ll, H o lle n -
No.
5
C o u n c il
fo r
D e n ta l
C a s tin g
S p e c ific a tio n
G o ld
w is h e s to a c k n o w le d g e
A llo y . th e
The
h e lp
of
back W.
T.
E. 0 .
R e se arc h S w ee n e y,
L ie b ig , E n g e lh a rd
A s s o c ia te s , N a t io n a l
E n cin o ,
B u re a u
In d u s C a lif .;
o f S ta n d
th e S p e c ific a tio n s C o m m itte e w ho se m e m b e rs
a rd s , W a s h in g to n ,
a r e : F. A . P e y to n
( c h a ir m a n ) , School o f D e n
S.
t is t r y ,
of
W e s t f ie ld , N . J .; D . L. S m ith , T h e J. M . N e y
U n iv e r s ity
G e o rg e D ic k s o n ,
436
M ic h ig a n ,
N a t io n a l
Ann
A rb o r;
B u re a u o f S ta n d
S. W h i t e
C o .,
C o ., H a r t fo r d .
D .C .;
N.
0.
P h ila d e lp h ia ;
T a y lo r , T h e E. M .
W is e ,
American Dental Association Specification No. 5 for Dental Casting Gold Alloy
4. SA M P L IN G , PRO CEDURES
(Fédération Dentaire Internationale Specification No. 7 for Dental Casting Gold Alloy)
IN SPEC T IO N A N D T E S T IN G
4.1 Sampling. Twenty pennyweight of alloy shall be pro cured at retail by a member of the American Dental Asso ciation. This sample shall be forwarded in the original un opened package or packages to the American Dental Asso ciation Council on Dental Research, 211 East Chicago Avenue, Chicago, Illinois 60611. In addition, the m anu facturer shall submit six tensile specimens for Types I, II, and III, and 12 specimens for Type IV in the as-cast con dition with button, sprue and vents attached. The diameter of these specimens shall be not less than 2.0 mm. (0.079 in.) nor more than 2.5 mm. (0.098 in.). The specimens shall be not less than 9 cm. (3.5 in.) long.
Second revision, approved in April 1965. Effective April 1, 1966
I . SCO PE A N D C L A S S IF IC A T IO N
1.1 Scope. This specification covers dental casting alloys based on gold and used in the fabrication of dental restora tions and appliances (6.1) 1.2 Classification. 1.2.1 Types. Dental casting gold alloy shall be of the following types as specified: Type I. Soft Type II. Medium Type III. H ard Type IV. Extra hard
4.2 Inspection. Visual inspection shall be used in determin ing compliance with the requirements outlined in 3.1 and 5. 4.3 Chemical tests. 4.3.1 Composition. The determined values for metallic constituents (table) shall be recorded to the nearest 0.5 per cent. When a determined value is midway , between a half and a whole number, the whole num ber shall be recorded. 4.4 Physical tests. 4.4.1 Preparation of specimens. Physical properties other than fusion tem perature shall be determined on càst specimens placed in a furnace at 700 ± 10°C. (1292 ± 18°F.) for 10 minutes and quenched in water at room temperature. Hardened specimens shall be prepared by placing the quenched specimens in an oven heated to 450 ± 5°C. (842 ± 9°F.). After they have been in the oven for two minutes the tem perature shall be reduced uniformly at 7 ± 1°C . (12 ± 2 °F .) a minute to 250 ± 5°C. (482 ± 9°F.) in 30 minutes and immediately shall be quenched in water at room temperature. Cast specimens shall be prepared by casting into a dental casting investment that satisfies the requirements of 2.1, using any dental casting method. The use of a wax pattern is not required.
2. A P P L IC A B L E S P E C IF IC A T IO N S
2.1 Specification. American Dental Association Specifica tion No. 2 for Casting Investment for Dental Gold Alloy is applicable to 4.4.1. (Copies of American Dental Association specifications may be obtained upon application to the Council on Dental Research, American Dental Association, 211 E. Chicago Ave., Chicago, 111. 60611, or to the American Dental Association Research Division, National Bureau of Standards, Washington, D.C., 20234.)
3. R EQ U IR E M E N T S
4.4.2 Compliance with requirements for tensile properties and hardness specifications. An alloy complies with the tensile and hardness requirements when all of the recorded values for strength, elongation and Brinell number, of three or more of a series of six castings of each heat treatment, meet the requirements.
3.1 Color. The color of the alloy shall be the color speci fied by the purchaser. 3.2 Composition. The composition requirements shall be as given in the table. 3.3 Physical properties. The requirements for physical properties shall be as given in the table. 3.4 M anufacturer’s instructions. Instructions for softening and for hardening heat treatm ent for Type III and Type IV alloy and the melting ranges of all types shall be included in the labeling or accompanying literature.
Table 1
Type
4.4.3 Brinell number. Specimens, not less than 2 mm. (0.08 in.) long, shall be sawed from the cast tensile spec imens, m ounted and polished, using progressively finer abrasive paper ending with a no. 3/0 emery paper. The
Composition and physical properties
Gold and metals of the platinum group
Min.
Min.
Hardened
Hardened
Quenched
Max.
Elongation 5-cm. gauge length
Tensile strength
Brinell number
Min.
%
Min. kg/cm2
Min. psi
Fusion tempera ture
Quenched
Hardened
Min.
Min.
%
%
Min. °C .
°F .
1
83
40
75
_
__
__
18
—
930
1706
II
78
70
100
--
—
900
1652
78
90
--
12
—
900
1652
IV
75
130
140 —
— —
12
III
— __
200
6,350
90,316
10
870
1598
2
REPO RTS OF C O U N C IL S A N D B U R E A U S • 437
Brinell number shall be determined by applying a 15-kg. load (33-lb.) on the specimen through a hardened steel ball 1.59 mm. (0.0625 in.) in diameter for 30 seconds. The diameter of the depression shall be determined by measur ing two diameters perpendicular to each other and the average shall be used in the calculation of the hardness number. The determined value shall be recorded as the nearest whole number. When thè determined num ber falls midway between two numbers, the even num ber shall be recorded. The Brinell number shall be calculated by the following form ula:
Bn =
P ---------------- ----------it (D /2 ) (D — V D 2 -
. — d*)
Where P = Test load in kilograms D = Diameter of ball in millimeters d = diameter of impression in millimeters 4.4.4. Tensile strength. The tensile strength shall be determined on the cast specimens submitted by the m an ufacturer. The loading rate shall be 100 ± 20 kg. (220 ± 44 lb.) per minuté. The specimen shall be loaded con tinuously from the initial load to the breaking point. The strength shali be computed on the basis of the original cross-section area. 4.4.5 Elongation. Elongation shall be determined on the specimen used in the test for tensile strength. Castings that break outside the gauge m arks may be repulled. Elongation shall be measured on a 5-cm. (1.97-in.) gauge length.. The determinéd value shall be recorded as the neatest 0.5 per cent. 4.4.6 Fusion temperature. The following apparatus shall be used: An electric furnace having a tube muffle approxi mately 25.4 mm. (1 in.) in inside diameter and mounted in a vertical position; a pyrometer accurate to ± 5"C. (± 9 °F .); an ingot of gold 13 mm. (0.5 in.) by 6.4 mm. (0.25 in.) by 0.51 ± 0.13 mm. (0.020 ± 0.0Ô5 in.) with holes having a diameter of 1.6 mm. (0.062 in.) centered 2.4 mm. (0.094 in.) from either edge at the center of the 6.4 mm. (0.25 in.) dimension; one piece of 20-gauge 0.81 mm. (0.032 in.) platinum or chromium-nickel wire (chromel) and a 300-Gm. (10.6-oz.) weight. The following procedure shall be used: The tip of an alumel-chromel or platinum versus platinum-rhodium ther mocouple of 20- or 22-gauge wire 0.81 mm. (0.032 in.) or 0.64 mm. (0.0253 in.) shall be bent into an “S” shape. The loop of the “S” curve nearest the long leads of the therm o couple shall be hooked into one of the 1.6 mm. (0.062 in.) holes of the ingot. The loop of the “S” curve nearest the hot junction shall be bent so that the hot junction lies ilear the. center of the ingot. A 20-gauge chromium-nickel or platinum wire shall be passed through the hole at the opposite end of the ingot and tied. The long leads of the thermocouple shall be secured at the top of the furnace so that the ingot hangs in the center of the muffle. A 300-Gm. weight shall be at tached to the chromium-nickel or platinum wire so that the weight hangs freely below the furnace. The top of the muffle shall be covered with a suitable refractory to prevent air currents. The bottom of the muffle shall be covered with a sheet of asbestos containing a hole 6.4 mm. (0.25 in.) in diameter. The hole in the sheet shall be centered with the center of the muffle opening to permit unobstructed passage of the loaded wire. The temperature of the furnace shall be raised to within 111°C. (200°F.) of the estimated lower limit of the melting range. The temperature shall then be increased 11 ± 3°C. (20 ± 5°F.) a minute. The tem perature at which the ingot breaks under the 300-Gm. load shall be recorded as the fusion temperature. The value shall be reported as
438 • JA D A , Vol. 72, Feb. 1966
the average of tests on three specimens and shall be re corded to the nearest degree Celsius (1.8°F.) 5. PR E P A R A T IO N FOR D E L IV E R Y
5.1 Packaging. The alloy shall be packaged in accordance with acceptable commercial practice. 5.2 Marking. 5.2.1 Lot numbers. Each container shall be m arked with a serial number or combination of letters and numbers which shall refer to the m anufacturer’s records for the particular lot or batch of alloy. 5.2.2 Date of manufacture. The date of m anufacture (year and m onth) shall be indicated on the container as a separate item or as a part of the serial number (5.2.1) 5.2.3 Net weight. The weight of the contents shall be marked on each container. Individual packets of small ingots o f'fro m 1.5 to 3.0 Gm. (one to two pennyweight) may have a tolerance of minus 1.0 per cent maximum. Packets of 30 Gm. or more (one troy ounce or m ore) may have a toler ance of minus 0.1 per cent maximum. 6. N O T ES.
6.1 Uses. The four types of alloys specified are ordinarily used for the following dental restorations and appliances. 6.1.1 Type I.
Those subject to very slight stress and where burnishing is desired.
6.1.2 Type II.
Those subject to moderate stress; % crowns, abutments, pontics, full crowns and saddles.
6.1.3 Type III. Those subject to high stress; thin % Crowns* thin cast backings, abutments, pontics, full crowns and saddles. 6.1.4 Type IV. Those thin in cross section and subject to very high stress; saddles* bars, clasps, crowns, thimbles and unit castings. 6.2 References. The following references will assist the observer in testing casting gold alloys for compliance with this specification. 6.2.1 Brumfield, R. C. Tentative standard methods of test ing precious metal dental materials (Technical Committee, Dental Gold Institute). JA D A 49:17 July 1954. 6.2.2 Coleman, R. L., Jr. Physical properties of dental materials (Gold alloys and accessory materials). Res. Paper No. 32, J. Research NBS 1:867 Dec. 1928. 6.2.3 Taylor, N. <3., Paffenbarger, G. C., and Sweeney, W. T. Inlay casting golds: Physical properties and specifica tions. JADA 19:36 Jan. 1932.
Dental Dealer Sales Dental dealers closed out 1964 with an average total sales increase of 7.9 per cent over 1963 and 28.4 per cent over the 12month average of 1957-59. In the fourth quarter, dealers averaged 9 per cent higher than 1963, with December sales up 15.3 per cent over a year ago.
American Dental Trade Association, Trade Trends, Feb. 12 1965.