Note: Descriptions are shown in the official language in which they were submitted.
104~893
An extremely effective agent for achieving optimum
bonding between the alloy and porcelain is the following com-
po~ition in percentages by weight, which is painted onto the
alloy in slurry form and fired to prepared the surface for bonding
to porcelain.
Constituent Proportions
~,old Powder 34.96
~5-15 microns)
Body Porcelain 26.22
~Hi-Life*)
Zirconium oxide 8.74
(10 microns)
Bonding Agent Liquid 30O08
(low fusing "flux"
soluble in a vehicle such
as glycerine or an alcohol)
*Hi-Life is a trademark of Howmedica Inc. Dental Division
- of ~hicago, Illinois
A metal alloy for making a dental restoration must
be strong, tough, resistant to tarnish, oxidation and corro-
sion, compatible with the human oral environment, ~biocompa- -
tible), have a ~uitable coefficient of thermal expansion, be
fu~ible to porcelain and have good castability. Most effective
dental alloys are relatively expensive because of their high
noble metal content. An object of this invention is to
provide a highly effective and relatively simple and economical
nonprecious alloy suitable for dental use including fusibility
to porcelain.
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In accordance with this invention a highly effective
and relatively economical nonprecious alloy for dental use
incorporates the following ranges of constitutents in per-
centages b.,v weight.
Constituent Proportional Range
Nickel Balance
Chromium 10.0-22,0
Aluminum 1,0-5.0
Silicon 0,5-2,0
Manganese 0.01-0.2
Molybdenum 0.0-7,0
An element selected from the
grouP consistinq of Strontium,
lanthanum and zirconium or a
combination of strontium and
zirconium, 0.0-2.0
gallium, and 1O0-3.0
iron 0.0-i~0
Particular examples of alloys of this invention are
listed below in Example I giving preferred compositions and pro~
portional ranges in percentages by weightO ~hese alloys have
been found particularly useful for dental service and are par-
ticularlyeffective for usion and tight adherance to porcelainO
Exam~le I
Element ~ Composition Ra~ge
Nickel 78.1 Balance
Chromium 13.5 10O0-22.0
Molybdenum 1,5 0O0-3,0 : ,
Aluminum 3O0 1,0-5,0
Silicon 1.0 0~5-2O0
Manganese 0.1 ODO1-OO2
`` 194~
Element ~3e5~ L5~a~l~bLE1æ~ Composition Range
An element selected from ~ group oon-
sistin~ of strontium, lanthanum an~or
ziroon~um or a ~x~i~ation of 0 0-2 0
strnntlum and zlrcomum~ O.5 -
~.allium 2~0 1.0-3.0
Iron 0.3 0.0-1.0
All oxbinations of strontium, lanthanum and zirconium
within the recited ranges are effective and a useful such
constituent is a 50~-50~ combination of strontium and zirconium.
1~ The bonding system that is necessary to achieve optimum
bonding between the alloy and the porcelain is as follows:
Constituent Proportions
Gold Powder 34.96
(5-15 microns)
lS Hi-Life Body Porcelain 26.22
Zirconium oxide 8.74
~10 microns)
Bonding Agent Liquid 30,08
Hi-Life is a trademark of ~owmedica Inc., Dental
2n Division, Chica~o, Illinois for a porcelain having approximately
the followin~ formulation in percentages by weight.
Constituent Composition
SiO2 68.64
A123 13.76
CaO 0.36
K2O 13.46
Na2O 2.29
Li20 1.49
The porcelain can also be any porcelain which has a
similar formulation, is intended for fabrication of fused por-
celain prostheses, and has a softening point of about 1200-1400F.
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~he bonding agent liquid is a low fusing "flux" soluble
in a vehicle such as glycerine or an alcohol. The flux may be
boron oxide or its salts, such as sodium borate or light element
oxides, i.e. Li20, Na20 and those light element oxides of the
first column of the periodic tableO The essential characteristic
is that the flux will react with the porcelain and with oxides
which are formed on the alloy during firing of the bonding
agent, to produce a low solubility, high tenacity, adherent
intermediate layer of oxides to which porcelain will adhere
during subse~uent application and firing. A range of composi-
tions can be effective under these conditions -- a typical range
would be that involving the following composition:
500 cc. glycerine
10-30 grams boric anhydride
1.14 cc. wetting agent
Another highly suitable bonding agent utilizing the
addition of a thixotropic agent such as Cab-o-Sil, maintains all
powders in solution for more consistent application and improve
the "painting" characteristics.
Such a formulation is as follows by weight per cent -
Glycerine 94.954
.. . .
B203 20502
Victawet No. 12 00237
Cab-o-sil 2,307
Victawet ~12 is the trademark of Victor Chemical Works
for a non-foaming, non-ionic wetting agent of the type (RO)PO-
(OR')2, where R is a medium-chain alkyl group, and R' is a water-
solubili2ing group. P205 content is 16%. It is an amber-colored
liquid; sp,gr. 1.121; pH, 4.7 (005% solution); surface tension,
28.8 dynes/cm. (0.2% solution 29C); Draves test, 902 sec at
0.6~ conc., and 32 sec. at 0.2% conc. (in hard water) insoluble
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in naphtha; soluble in alcohols, acetone toluene; forms a milky
solution in water~ Uses: As a wetting agent in acid and alkaline
solutions, and as a carrier for acid dyesO It provides level
shades and uniform penetration in package dying of nylon, etc.
Cal-o-sil is the trademark of Godfrey L~ Cabot, Inc.
or a colloidal silica prepared in a hot gaseous environment by
a vapor-phase hydrolysis of a silicon compound instead of by the
usual a~ueou~ precipitation process~ Its outstanding properties
are high chemical purity, low water content, enormous external
surface area, and high degree of particle separationO Cab-o-sil
functions in extremely small quantities as a reinforcing agent
in rubber and plastics, a suspending and flatting agent in paints,
a~ a thixotropic agent in various resins, as an emulsion stabili-
zer, and as a thickening and gelling agent~
The manner in which the above liquid is used as a bond-
ing agent is as follows: A thin slurry is made using Liquid #2A
and the opa~ue or undercoat porcelain~ This is then painted
onto the appliance in the areas which are to receive porcelain
and the slurry is then fired, A specific ratio of powder/liquid
2~ is not reauired, The conditions which are necessary for success
are that the slurry is paintable and, after painting, produce a
general blocking out of the underlying metal colorO
It is believed that the particular constitutents have
the following functions in the alloys of this invention:
Nickel - Major component chosen for its inherent
resistance to corrosive attackO
Chromium - To enhance the corrosion resistance of
the alloy and also as a solid solution
strenghener 1~
Mol~bdenum - Enhances the corrosion resistance of
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the alloy and adjusts the coefficient of
thermal expansion of the alloyO
Aluminum - Added as a deoxidizer and effects the
coefficient of thermal expansion of the
alloyO
Silicon - Added as a deoxidizer and also aids in
obtaining fluidity for ease of casting~
Manganese - Acts as a safeguard against any possible
sulfur contamination
Iron - Lowers the coefficient of thermal expansion
and contributes to the metal to porcelain
bond,
Lanthanum~ strontium, zirconium - The function of
these elements is to effect a porcelain to
metal bondO
~allium - Improves the bonding characteristics and
increases the fluidity of the alloy to
facilitate casting~ -
These alloys were designed for use as an under-struc-
ture onto which porcelain is fused for making a fixed bridge
type of dental restorationO General characteristics of these
alloys are:
lo Ability to successfully melt and cast using either
an oxy/acetylene torch or an induction type casting
machine.
2, Precision dental castings can be achieved when cast
into dental investments,
3. Matching coefficients of thermal expansion between
the alloys and the porcelains which are currently - .
3~ being used~ :.
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4. Corrosion resistance to oral cavity fluids and
tissue tolerance,
5, Brinell Hardness values in the range of 170-210.
6. Mechanical properties sufficient to withstand
the forces employed in the mouth during mastication.
Aside from the practical evaluation of these alloys
which involved the construction of porcelain fused to metal bridges,
the following specific properties were determined in the manner
described below.
-- Coefficient of Thermal Expansion
Equipment - Theta Dilatronic I, automatic recording
dilatometer D
Test specimen - 2.000 " long x 0.250" diameter
Test method - Determine the coefficient of thermal
expansion between 200F and 1200F,
-- Hardness
Equipment - Rockwell Hardness tester
Test specimen - cast piece 1/2" x 3/4" x 1/8" thick~
Test method - the hardness numbers were determined in
three states:
1, As Cast Condition
2. Annealed - quenched af~er heating for 10 minutes
at 1290F.
3, Heat treated - 1800F. for 30 minutes followed by
a slow air cool.
Conversion to Brinell hardness via conversion chart for
this type of alloy.
-- Tensile Properties
Equipment - Instron Tensile Machine
Test Specimen: cast piece 2-7/8" long with 12024
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- 1~4~)893
threaded ends and a radius of 1/4" from the threaded
portion to the test area. The test area is 1-3/8"
long with a diameter of .09" + .01" diameter.
NOTE: This is the specimen required by the ADA in
Specification No. 14.
-- Corrosion and Tarnish Resistance
Adequate corrosion resistance was determined through
a compilation of results of test involving implant
studies, in-vitro corrosion resistance vs. a negative
control, and through clinical evaluations. Tarnish
resi~tance is evaluated by exposure to a dilute iodine-
alcohol solution at 37Cr
The ~ollowing properties were determined from the afore-
mentioned tests:
A tvpical alloy gives the following results: -
As Cast Condition
proportional Limit ~psi) 60,000
0.2 Yield Stress (psi) 75,000
Ultimate Tensile Strength ~psi) 85,000
Elastic Modulus (psi) 25-26 x 106
Elongation ¢%) 2015
Hardness, Rockwell B 93-99
Heat Treated Condition
Proportional Limit (psi) 40,000 -
0.2% Yield Strength ¢psi) 51,000
Ultimate Tensile Strength (psi) 75,000
Elastic Modulus ~psi) 25-26 x 106
Elongation ~%) 6~6
Hardness, Roc~well B 85091
Thermal Expansion 8.25 x 10-6 in/in F.
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