Note: Descriptions are shown in the official language in which they were submitted.
3~
This invention relates to improved dentifrice abrasives.
More particularly, the present învention relates to novel,
alkaline earth-treated, precipitated silica abrasives which are
suitable for use in therapeutic toothpaste compositions contain-
ing both soluble fluoride salts as enamel solubility reducing
agents and soluble phosphate salts as dental pellicle film
penetration agents. The invention further relates to methods
for preparing these improved precipitated silica abrasives and
to toothpastes containing the improved abrasives including tooth-
paste embodiments which comprise both enamel solubility reducing
agents (i.e. fluoride) and dental pellicle film penetration
agents. Such toothpaste compositions exhibit both high fluoride
compatibility and high cleaning performance.
This application is related to copending Canadian
application 2a5,885 filed August 31, ~977.
The function of an abrasive substance in ~ormulations
intended fox use in the oral cavity is to remove various
deposits, including pellicle film, from the surface of the
teeth. Pellicle film is tightly adherent and often contains
brown or yellow pigments and thus imparts an unsightly appear-
ance to the teeth. An advantageous toothpaste abrasive material
should maximize film removal without causing undue abrasion to
the hard tooth tissue. Dental researchers are continually con-
cerned with developing toothpaste abrasives which demonstrate
satisfactory levels of cleaning and which are not unduly abrasive
and damaging to the oral tissue.
B
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In addition to abrasives, -therapeutic too-thpastes typically
contain fluoride ion sources. The beneficial reduction in the in-
cidence of dental caries resulting from the topical application to
dental enamel surfaces of solutions containing fluoride ions is
well known. Especially at solution pH's between about 4 and 8,
Eluoride ions are believed to interact with enamel to reduce the
acid solubility of such enamel. Enamel 50 treated with fluoride
is more resistant to -the formation of den~al caries. Accordingly,
therapeutic toothpaste compositions are formulated to provide
fluoride ion availability in brushing solu-tions formed in the oral
cavity during use.
It has been postulated that the e~fectiveness of fluoride
-treatment in providing enamel antisolubility/anticariogenic bene-
fits is dependent upon the amount of fluoride ion which is avail-
able for uptake by the enamel bein~ treated. It is, of course,
therefore desirable to formulate toothpaste compositions which
provide maximum fluoride ion availability in brushing solu-tions
formed therefrom. However, efforts to utilize such ionic fluoride
anticariogenic agents in toothpastes suitable for home use have
been unable to provide the theoretical maximum soluble fluoride
because of the tendency for ionic fluoride to be inactivated and
thereby rendered unavailable for enamel uptake. That is, -the tooth-
pastes lose, upon storage (at rates which increase with tempera-
ture), the capabili-ty of providing the theoretical ma~imum amount
of soluble fluoride. E'or purposes of this invention, the "soluble
fluoride" content of any given toothpaste composition refers to
the ppm concentration of fluoride ion which is found in the super-
natant sample centrifuged from 1:3 by weight slurry of the tooth-
paste in water (1:3 = toothpaste:water).
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.,
Fluoride ion sources ~end to interact with toothpaste
impurities and with such toothpaste componcnts as abra-
sives/ bu~fers, etc. Such interaction diminishes the
~bility of the fluoride sourcé to provide "soluble fluoride"
upon use. The propensity of the toothpaste compositions
herein to maintain their levels of soluble fluoride af ter
storage is expressed here~na~ter as "toothpaste fluoride
compatibility". Thus, the -toothpaste fluoride compatibility
of a particular toothpaste composition is that percentage
10 - of the theoretical maximum amount of fluoride source that
is actually measured as soluble fluoride after storage for
a specified time and at a specified temperature (e~g. one
week at 120F.~. Similarly, the propensity of such a den-
tifrice component such as the abrasive to interact with
the fluoride source to diminish the measured "soluble
fluoride" level from the theoretical maximum amount of
fluoride source (particularly in the presence of pellicle
; film penetration agents described in detail below~ is
~expressed as "abrasive fluoride compatibility". The test
procedures used herein to determine "toothpaste fluoride
compatibility" values and "abrasive fluoride compatibility"
~ .
values are described more fully hereinafter.
~;
` One toothpaste component which can pose special dif-
~ .
ficulties in f~ormulating fluoride too~hpastes is a preci-
pitated silica abrasive component. Precipitated silica abra-
sives are desirable for use in toothpastes since they have
desirably low dcntin abrasion values~ Certain prior art
precipitatcd silica abrasives are ~enerally compatible
with soluble ~luoride sourccs but have insufficiently hi~h
,
:,
:;
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a~rasivity to provide effective cleaninc3 performance.
Certain other prior art precipitated silica abrasives
provide acceptable cleanincJ performance but llave low abra-
sive fluoride compatibility as measured by the method here-
inafter It is believed that no prlor art precipitated
silica abrasives give both high"a~rasive fluoxide compa-
tibility" as well as acceptable cleaning performance,(as
indicated by s-tandard Radioactive Den~in Abrasion vaIues~
There is thus a clear need to ormulate precipi-tated
silica abrasives which exhibit high "abrasive fluoride
compatibi1ity" as well as acceptable cleaning performance.
According]y, it is an object of the presen-t invention to
provide precipitated silica abrasives which eYhibit high
"abrasive fluoride compatibility" as well as acceptable
cleanlng performance.
Another dentifrice component which can be especially
destructlve of soluble fluoride content in certain tooth-
`: : :
paste composltions 1S soluble phosphate. Soluble phosphate
salts, upon toothpaste use, serve to enhance the abili-ty
, ~ :
o~ fluoride ions to penetrate dental pellicle film.
For this reason, soluble phosphate salts are deslrably
included in fluoride toothpaste composi-tions. Ilo~ever,
particularly in combination with silica dental abrasives,
soluble ~hospha~te pellicle penetration agents tend to pro-
mote loss of soluble fluoride in toothpastes containin~ these
ma-terials and, thus, the toothpastes e~hibit low toothpaste
fluoride coMpatibility values. Thcre is thus a clear need
to formulate precipitated silica abrasives which provide
high toothpaste fluoride compatibility when utilized in
fluoride toothpastescontaining soluble phosphate salts as
; pellicle ~ilm pcnetra-tion agents.
..
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There is thus a further need to provide fluoride
toothpastes which can contain precipi-tated silica abrasives
in combination with soluble phosphate salts. Accordingly,
it is an object of the present invention to provide fluoride
toothpaste compositions which contain soluble phosphate salts
and precipitated silica abrasives and which nonetheless
retain relatively high levels oL soluble fluoride even
after periods of storaye.
It has been surprisingly discovered that the above
objectives can be realized by the present invention which
provides a nove~ precipitated siliaa abrasive which has
been treated with an alkaline earth material, particularly
cal;cium. By utilizing the instant den-tal abrasives, fluoride
; toothpastes- particularly those embodiments containiny
; 15 soluble phosphate~salts - can be realized which have high
toothpaste ~fluoride compatibility and excellent cleaning
performance.
: ~
; ~ It is of course well known that therapeutic tooth-
~; pastecompositions contain calcium phosphate materials as
~0 abrasives~but these calcium materials are present inllarye
amounts as described above and illustrated for example in
U.5. Patents 3,624,199, issued November 30, 1971, Norfleet
et al, and 3,864,471, issued February 4, 1975, Mills et al.
Toothpaste compgsitions are also known in the art which
contain smal~ amounts of alkallne earth metal ions, such
as calcium ions, and compositions of this type are illus-
trated by U.S. Patent 3,991,177, issued November 9, 1976,
Vidra et al. This patent discloses toothpaste compositions
~,
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which contain a s-tabilizer-activator for a dex-tranase enzyme
agent with -the stabilizer-ac-tivator being a salt such as
calciw-n chloride present in an amount of .001 -to 0.3 weight
percent. rrhis composition can also contain therapeutic
fluoride and the abrasive agel1t is calcium carbona-te.
Other prior art which cliscloses toothpaste cornposi~
tions containing alkaline earth me-tal compounds or ions
include U.S. Patents 3,095l356, issued June 25, 1963l to Moss;
3l122l483, issued February 25l 1964, -to Rosenthal; 3,669,221,
issued June 13, 1972 to Hase; 3/782/446/ issued January 1
1974l to Walter; 3,842,168, issued October lS, 1974, to
Colodney; and 3,689/537/ issued September 5, 1972, to Kuder.
However, none of these prior art patents disclose thera~
peutic toothpaste compositions which contain as the abrasive
agent a low structure precipitated silicon dioxide which
contains about 10 to 300 par-ts per million of alkaline
earth metal ion as described herein.
~''' . ~
98~3~
There is provided by the present invention a novel
abrasive material for toothpaste compositions which comprises
in its broadest embodiment, a precipitated silicon dioxide
which is prepared from fresh water alkali metal silicate by
acidulation. Such precipitated abrasives contain about 10-
300 partsper million of alkaline earth metal ion, and are
characteri~ed by an RDA value of at least 40, an oil absorption
value of abou-t 70-95 ccs/100 gram, a pack density of about
0.24 to 0.55 grams per milliliter, a loss on ignition value of
about 4 to 6% and a BET surface area of about 100 to 250 m /g,
and preferably with an average particle size of about 5 to 15
microns. Also provided is a method for the preparation of the
novel abrasives of this invention which in general comprises
formation of a low structure precipitated silicon dioxide by
the acidulation of certain fresh water sodium silicate solutions
with a mineral acid and subsequent treatment of the resulting
wet cake with the required amount of alkaline earth metal ions.
The present invention further relates to fluoride-
containing toothpaste compositions which exhibit minimal loss
of soluble fluoride upon storage at normal temperatures and
which provide excellent cleaning performance. Such toothpaste
~- compositions comprise the amorphous, precipitated silica
abrasives of the present invention, a source of fluoride ions,
a binding agent, a humectant and water. Such toothpaste
compositions provide a pH of from about 4.0 to 8.0 when slurried
with water in a 3:1 water/composition weight ratio.
The amorphous, precipitated silica abrasives of the
present invention comprise from about 6% to 3~ by weight of
the toothpaste compositions.
-- 8 --
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The fluoride ion source comprises from about 0.01~ to
3.0% by weight of the too thpas te compositions and can be any
water-soluble material which yields fluoride ions in aqueous
solution.
The binder comprises from about 0.2% to 2~ of the
toothpaste composi tions .
The humectant comprises from about 3% to 55~ by weight
of the toothpaste composition. The water in the toothpastes
herein comprises from about 15% to 80~ by weight of composition~
::,
~f ,~
;'
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r
~L~3~
\
The present invention relates to novel, precipitated
silicon dioxide dentifrice abrasives, methods for their
preparation, and their incorporation into toothpastes to provide
re~ulting compositions having excellent toothpaste fluoride
compatibility values and excellent abrasivity values. The
toothpaste compositions herein further essentially comprise a
water-soluble fluoride ion source, a binding agent, and certain
amounts of humectants and water. Each of these components as
well as optional in~redients, composition use and composition
preparation are described in detail as follows:
PRECIPITATED SILICA DENTAL ABRASIVE
The presen~ invention relates to low stxucture
precipitated silicon dioxide materials which are suitable for
use as dental abrasives. Such abrasives have ultimately
associated therewith about 10 - 300 parts per million, preferably
10 - 100 parts per million, of alkaline earth metal, preferably
calcium, based on the amount of recoverable dry material. This
dental abrasive material is characterized further by generally
having a percent abrasive fluoride compatibility in the range
of at least 90%, a RDA of at least 40, perferably from about 70
to 120, a loss on ignition (hereinafter "LOI") in the range o
4 - 6~, a pack density in the range of about 0.24 to 0.55 grams
per milliliter, an oil absorption in the range of about 70 - 95
cc/100 grams and a BET surface area in the range of about 100 -
250 m /y with an average particle size in the range of 5 - lS
microns. When incorporated into a toothpaste, the dental
abrasives herein provide high fluoride compatibility and excellent
cleaning performance. The definition of low structure silicon
dioxide materials is given in United States Patent No. 3,893,840,
; 30 mentioned above.
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., ~; ~ . ', ~, ' : `'
3Q
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The dental abrasive materials of the present invention
are precipitated silicon dioxides which are prepared by the
general methods described, for example/ in prior U.S. Patents
3,893,840, issued July 8, 1975, to Wason; 3,988,162, issued
October 26, 1976, to Wason; and 4,067,746 issued January 10,
1978. Abrasives produced by such methods are subsequently
treated with alkaline earth metal ions in the manner described
herein. In general, the process for preparation of the silicon
dioxides comprises the acidulation of an aqueous alkali metal
silicate solution preferably with a mineral acid to effect
precipitation of silicon dioxide. The acid addition is continued
to an acid pH and the resulting precipitated silicon dioxide is
then removed such as by filtration, and washed to remove any by-
product materials such as alkali metal sulfate, to provide a wet
cake. The resulting wet cake is then reslurried in its own water
or with additional water and thereafter is treated with the re-
quired amount of alkaline earth metal ions in the form of a
soluble salt to provide the abrasive materials of this invention.
The abrasive products of the present application are to
be distinguished from the precipitated silicon dioxide composi-
tions which have been treated with alkaline ear~h metal ions as
disclosed in my U.S. Patent 4,159,280 issued June 26, 1979. The
silicon dioxides treated with alkaline earth metals as disclosed
in U.S. Patent 4,159,280 are abrasives which are useful or
incorporation into toothpaste compositions so as to prevent
corrosion of unlined aluminum toothpaste tubes. Such corrosion~
3~
inhibitin~ precipitated silicon dioxides as are described
in U.S. Patent 4,159,280 are silicon dioxides prepared by
a so called sulfate liquor method. In that me~hod, an
electrolyte such as alkali metal sulfate is admixed with the
alkali metal silicate liquor during acidulation with mineral
acid as disclosed for example in my U.S. Patents 3,960,586
and 3,928,541. While the products of V.S. Patent 4,159,280
may be described as precipitated silicon dioxides having
intimately admixed therewith an amount of alkaline earth
metal ions which is within the range of that of the present
invsntion, the abrasive products of the present invention
have different characteristics from the silicon dioxides
derived from the sulate-liquor method. The sulfate liquor
silica materials, when utilized in certaln fluoride-
containing toothpaste compositions, do not provide ~he
superior fluoride compatibility values of the present
invention. The superior fluoride compatibility values of
the dental abrasives of this invention are achieved only
with th~ silicon dioxides prepared from so-called fresh-
water alkali metal silicate process as described herein.
The silicon dioxide abrasives of the present
invention, are alkaline earth metal~treated precipitated
silicon dioxides which are prepared from fresh water silicate
solutions. Such a process does not make use of any electro-
lyte such as sodium sulfate in preparation of the untreated
precipitated silicon dioxide. Further, in the products
of the present invention, it has been found that the pre-
sence of alkaline earth metal ions intimately associated
with the resulting silicon dioxide, must be present within
a particular narrow range to provide the fluoride compati-
bility necessary for use in the present invention. Thus,
- 12 -
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the abrasive products of the present invention have fluoride
compatibility values of at least 90~, whereas those abrasives
of the U.S. Patent 4,159,280 generally give cc,mpatibility
values of 89% or below as determined by the toothpaste fluoride
compatibility tests described in this application.
It is theorized that the improved fluoride compatibility
of the instant dental abrasives is based on the manner in which
the silanol groups therein are attached to the surface of the
silicon dioxide product. Thus, in the fresh water silicate
derived silicon dioxide of the present invention, the silanol
groups on the surface of the material are believed to be more
available than on the sulfate liquor silicate derived silicon
dioxide as disclosed in my U.S. Patent 4,159,280. Further,
the surface acidity of the fresh water silicon dioxides, due
to the silanol groups, is higher than the corresponding acidity
of the silicon dioxides derived from the sulfate liquor process.
Because the silanol groups are different in these two materials,
the intrinsic surface acidity does not respond well to calcium
treatment for fluoride compatibility in the sulfate liquor
products. The products of U.S. Patent 4,159,280 also have
higher abrasive values than the silicon dioxides of this
application. Therefore, the instant abrasives are to be
distinguished from the alkaline earth metal treated silicon
dioxides disclosed in U.S. Patent 4,159,280.
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The instant precipitated silicon dioxide abrasives
are preferably prepared by charging an aqueous solution of
an alkali metal silicate solution, preferably an alkali metal
silicate having an SiO2 to X20 mole ratio of about 2.0 to 2.7
wherein X is an alkali metal, and most preferably a sodium
silicate solution, to a reactor for acidulation. The aqueous
sodium silicate solution is a fresh water solution having a
sodium silicate concentration range of about 10 - 17 weight
percent, and more preferably 12.5 to 15.5 weight percent,
and a sodium silicate composition of Na2O-2.6 SiO2 for best
results. The aqueous sodium silicate solution is then raised
to a temperature of about 50 to 95C, preferably 77 to 91C,
and with continuous agitation the solution is acidulated by
the addition of an aqueous ~olution of a mineral acid having
a concentration of about 10 - 20 weight percent at a
substantially constant pH in the range of about 8.5 to 10.5.
The mineral acid is preferably sulfuric acid as sulfuric acid
provides best results but as is known in the art ~See U.S.
Patents 3,988,162, 3,893,840 and 4,067,746), o~her acidulation
agents such as nitric acid, phosphoric acid, hydrochloric acid,
carbonic acid and the like can also be employed.
In the most preferred embodiment only a portion
of the alkali metal silicate solution is charged to the
reactor, brought to temperature under agitation, and the
sulfuric acid and remainder of the alkali metal silicate
1,. - ' -
solution simultaneously added to the initial silicatesolution at the reaction temperature. Preferably about
8 to 12 wt. % of the metal silicate is initially charged
to the reactor. The remaining portion is then added with
the sulfuric acid. The time period over which the alkali
~ metal silicate and sulfuric acid are added to the alkali
; metal silicate in the reactor can be predetermined and is
generally based on the volume of the reactor and the
difficulties in control of the temperature and agitation.
After completion of the addition of the alkali metal silicate
solution, the acidulation agenb is continually adaed until
the pH of the reaction slurry falls below about 6.0 and
preferably to within the range of about 4.6 - 5Ø The
resulting slurry is the precipitated silicon dioxide contained
in the reaction medium.
After the pH of below 6.0 is reached, the slurry is
then heated for a digestion period at a temperature of 10
to 30C above the reaction temperature and the reaction pH
again adjusted as necessary. The resulting slurry is then
filtered and washed with additional water to remove any
reaction by-product such as sodium sulfate which may be
contained in the silicon dioxide product. The wet cake
moisture o the resulting filter cake is in the range of
about 60 - 66% and is a low structure material. The above
reaction to this point is generally the same as disclosed in
my prior Patents 3,893,840, 3,988,162 and 4,067,746,
mentioned above, in the preparation of silicon dioxide
prepared from fresh water alkali metal silicate.
3~
- In the process oE the presen~ i~vention, at the
point of filtra-tion and ~ashing of the silicon dioxide
wet cake, the material is then subjected to treatment
with alkaline earth metal ions to produce the new abra-
sive products of the present inventlon. In accordancewith the process oE the present invention, the wet washed
filter cake is then reslurried in its own water or with
the addition of fresh water at ambient temperature with
agitation. While under agltation, this slurry is then
treated with sufficient alkaline earth metal ions, pre-
ferably calcium ions, in the form of a salt su~ficiently
soluble to provide an amount of alkaline earth metal
ions corresponding to about 10 to 300 parts per million,
or .001 to .03 weight percent tbased on the weight of
the dry recoverable silicon dioxide), of alkaline earth metal
ions in-tirnately associated with the silicon dioxide.
,
The alkaline earth metal ion added at this point
~ is preferably caIcium lon because of its readily availabil-
; ity, low cost, and ease of incorporation into the silicon
dioxide. The calcium ions can be incorporated into thè
silicon dioxide at this stage in any sufficiently water
soluble form (ite., soluble in water to the extent of at
least .07 g/100 cc H2O at 20C~) such as with solutions
of calci~ nitrate,' calcium oxide, calcium hydxoxide, or
calcium chloride. Lime or calcium hydroxide is preferred.
Also, solutions of oryanic salts such as calcium acetate,
calcium formate, and the like can also be used. The cor-
responding strontium and magnesium salts of the alkaline
earth class can also be used. Food yrade sal~s should be used.
~i
~b'9 ~ ~3~
, ~
A:~ter t~eatmcnt wil~ll the al]:-lline earth met~l ion, '~ -. ~
the cake slurr~, is th~n ayitated vicJorously for 10-20
minut~s, preferably 15 minutes, -to provide the effective .
level o~ alkaline earth metal for treatment on~o the sur-
ace Orc the silicon dio~ide abrasi~re. The resulting pro- ,~
duc~. is then cl.ried. Preferably dr~ing ls conduc-ted in
a spray clryer at an inlet temperature o~ ~83C. and outlet
temperature o~ 122C. as known :i.n ~he art, and sub.sequenl:ly
milled to the desirecl dec;ree oE ~ineness.
TOOTHPP~S'rl'".S
Also provicled by the present. inven-tion-herein are
therapeutic toothpastes containiny the instan-t novel
precipitated sili.ca abrasives. In acldition to the instant
abrasives, the toothpaste compositiolls o~ the present
invention ~urther cornprise certain amounts o a ~ater-
soluble fluori.de ion source, a hindi.ng acJent, a humectant
and water. Each oE these adcliti.onal toothpaste components
as well as optional toothpaste components are described in
detai,l as ~ollows:
A. A ~
.. As indicated above, the instant precipitat_d silica
abrasives are particularly suitable or incorporalion into
fluoride-contai.nincJ therapeutic toothp,3s.te compositions.
Therapeutic toothpastes employin~J such abrasives provide
satisactory tooth.cl.eaning perormarlc:e and also possess
excellent abrasi.ve 1uoride compati.bll.i.t~ characteristics.
The instarlt toothpaste composi~ic)ns esc-,entially contain
from about 6o to 35 %, preferahly from about 10% to 2.0~O/
by ~eight o~ -the, i.nstant preci.pi.tated silica abrasi,ves.
~ ' ' .
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B. Fluoride IOII Source
The instank therapeutic toothpaste compositions further
contain from about 0.01% to 3%l preferably from about 0.1% to
l.Q~, by weight of a water-soluble, fluorine-containing
material which yields fluoride ions in aqueous solutions. Such
fluoride ions combine with dental enamel and thereby reduce
enamel solubility in acid. Application of fluoride ions to
dental enamel serves to protect teeth against decay.
A wide variety of fluoride ion-yielding materials can be
employed as souxces of soluble fluoride in the instant composi-
tions. Examples of suitable fiuoride ion-yielding materials
are found in Briner et al; U.S. Patent 3,535,421; issued October
20, 1970 and Widder et al; U.S. Patent 3,678,154; issued July
18~ 1972. Preferred fluoride ion sources for use herein
include sodium fluoride (NaF), stannous fluoride (SnF2), potassium
fluoride (KF), potassium stannous fluoride (SnF2-KF), indium
fluoride (InF3), zinc fluoride (ZnF2), ammonium fluoride (NH4F),
and stannous chlorofluoride ~SnClF). Sodium fluoride and
stannous fluoride are particularly preferred as well as
mixtures thereof.
Preerably the instant toothpaste compositions provide
from about 50 ppm to 500 ppm, more preferably from about 100
to 400 ppm, of fluoride ions in the aqueous solutions which
contact dental surfaces when the toothpastes o the present
invention are used in the mouth. As described more fully
hereinafter, such solutions are simulated by preparing 3:1
water/toothpaste slurries ~by weight) of the toothpaste
compositions herein and by subsequently centrifuging such
slurries to obtain an aqu~ous supernatant. The fluoride ion
concentration in such a supernatant is taken as a measure of
the "soluble fluoride" provided by any given fluoride tooth-
paste composition.
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C. Binder
__
A binder is essentially employcd to prevent separ-
ation of the liquid and solid phases in tlle toothpaste
compositions herein. Such binder materials ~re well known
in the toothpaste art. The most conventiollally used bin-
ders are the seaweed colloids such as Caxrageenan (Irish
moss or Viscarin ~ and derivatives of cellulose, such
as sodium carboxymethyl cellulose and hydroxyethyl cellu~
lose. Another type of binder which is suitable for use herein
is gums such as 1) vegetable gums, e~g., guar gums and
2) fermentation products e.g., xanthan ~-~. The binder
component generally comprises from about 0.1% to 5~, pre-
ferably 0.2%to 2% by weight of the toothpaste compositions
he~ein. Since the natural and synthetic tlater dispersions
of water binders are subject to microbial or mold attack,
the toothpastes herein can optionally contain a relatively
s~all amount of a preservativ~. Examples of preservatives
typically employed are the esters of parahydroxyl benzoates.
Toothpaste binders are more fully described in
}lager et al, U.S. Pa~ent 2,839,448, issued ~une 17, 1958;
and DiGiulio, 3,862,307, issued January ~1, 1975.
D~ ~lumectant
Another essential component of the toothpaste com-
positions here1h is a humectant. Suitable humectant ma-
terials are also well known in the toothpaste art. The
humectant ~erves to retain moisturç and thereby to keep
~le toothpaste compositions ~rom hardening upon exposure
to air~ Cert2in humectants ~an also impart desirable
sweetness or flavor to toothpaste composi-tions. The humec-
tant generally comprises from about 5% to 55~, ~referably
~rom about 20~ to 36~, by weight of the tootllpaste compo
ions herein. - 19
3~D
~uitable humec~ants for use in this invention in-
~lude edible polyhydric alcohols such as qlycerine, sor-
bitol, xylitol and propylene glycol~ Sorbitol i5 fre-
~uently employed as a 70~ a~ueous solution known as
~orb~ ~0 Mixtures of glycerine and sorbitol are espe-
cially preferred as th~ humectant component o the tooth-
pa~te co~positions herein~
E~ Wa~er
__ .
Wat~r is another essential element o the ooth~
pastes o~ thi~ invention. Water employed in the prepar-
ation o~ commercially sui~able ~oothpastes ~hould be
deionized and free o organic impurities. Water comprises
~ro~n about 1596 to 80%, pre~erably from about 15% to ~0%,
by weight of thb toothpaste compositions herein.
Y. O~
In addition to the above described essential com~
ponents, the toothp~stes of this invention can contain
, ~ariety of optional conventional toothpa~te ingredients.
Such optional inyredie~ts include (1) sudsing agents,
~o : ~2~ pellicle film penetration agents, ~3) 1avoring and
sweetening agents, (4) anticalculus, antiplaque agen~s,
and ~S) pigments and coloring agents.
1 ) Suds~
A preferred optional ingredient is a sudsing agcnt,
Suitable sudsing agents are those which are rioason~bl.y
stable and form suds throughout a widc p~l range , i . e .,
non-soap anionic, nonionic ~ cationic t zwitterionic anc~
amphoteric organic synthetic detergents~ Sudsing ~gcnts
of thcse t:ypes are described more fully in ~grico~ a ct al;
U.S. Pat~nt 3,95~,4587 issued ~ay 25, 1976 and in ll~efcle;
lJ.S. raten~ 3?~37~ 807; 1ssucd Fcbruary 10, 1976,
~ 20 -
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Anionic sudsing agents useful herei~ include the
water-soluble salts of alkyl sulfates having from 8 ~o
18 carbon atoms in the alkyl radical and the water-soluble
salts of sulfonated monoglycerides o~ fatty acids ha~ing
from 10 to 18 carbon atoms~ Sodium lauryl sulate and
sodium coconut monoglyceride sulfonates ar~ examples oP
anionic s~rfactants o~ th.is type. Mixtures o anionic
~urfactants can also be employed.
The nonionic sudsing agents which can be used
in the toothpastes of the present invention can be broadly
defined as compounds produced by th~ condensation of alkylene
oxide groups thydroPhilic in na~ure) with an organic
hydrophobic compound which may be alipha~ic or alkyl-
aromatic in nature. Exampl s of suitable nonionic sudsiny
agents include the Pluronics ,polyethylene oxide con~en-
~at~s of alkyl phenols, products d~rived from the CGn-
:densation of ethylene oxide with the reaction product
of propylene oxide and ethylene diamine, ethy.l~ne oxide
con~ensates of aliphatic a}cohols, long chain tertiary
a~ine oxides, long chain tertiary phosphine oxides, long
chain dialkyl sulfoxides and mixtures of such materials.
~ The zwitterionic synthe~ic sudsin~ agents useful
in the toothpast~s of th~ present invention can be broadly
described as de~ivatives of aliphatic quaternary ammonium
phosphonium, and sulfonium compounds, in which the ali-
p~atic radicals ~an be straight ch~in or branched, and
wherein one of the aliphatic substituents contai.ns from
~bcut B to lB carbon atoms and one contains an ~nionic
water-solubilizin~ gxoup~ e~., carboxyt sulfollate~ sulfate,
phospha~e, or p~ospllonate.
2' -
e
. .. ~. .. ~ . .
33~
The cationic sudsingagents useful in the tooth-
pastes of the present invention can be broadly defined
as quaternary ammonium compounds having one long alkyl
chain containing from about 8 to about 18 carbon atoms
such as lauryl trimethylammonium chloride; cetyl pyridinium
chloride; cetyl trimethylammonium bromide; di-isobutyl-
phenoxyethoxyethyl-dimethyobenzylammonium chloride;
coconutalkyltrimethylammonium nitrite; cetyl pyridinium
fluoride, etc. ~specially preferred are the quaternary
ammonium fluorides described in U.S. Patent 3,535,421,
Briner et al, issued October 20, ].970, where said quaternary
ammonium fluorides have det~rgent properties. The cationic
sudsing agents can also act as germicides in certain of
the toothpastes herein.
The amphoteric sudsing agents useful in the present
invention can be broadly described as derivatives of
aliphatic secondary and tertiary amines in which the
: aliphatic radical can be straight chain or branched and
wherein one of the aliphatic substituents contains from
about 8 to about 18 carbon atoms and one contains an anionic
water-solubilizing group, e.g. carboxylate, sulfonate, sulfate,
phosphate, or phosphonate.
The sudsing agent can be present in the toothpaste
compositions o this invention in an amount from 0.1% to 6%
by weight of the total composition.
- 22 -
,~
,:
3~
~) Phosphate Pell_c.1e F'enetration ~ent
~he toothpaste cornpositio~s of the present inven-
tion contain as a hiyhly preEerred op-tional component
fro~ abou~ 5% to :1.2~, preferab.l.y from about 7% to ll~,
by weight of a water soluble pllosphate "pellicle penetra-
tion agent"~ Such soluble phosphate salts serve to promote
transfer of fluoride ions through the naturally-occurring
salivary pelli.cle film formed on the teeth. Fluoride-
containin~ toothpas-tes which utilize the level.s of phos-
phate salts prescribed herein demons-trate enhanced fluo-
ride pellicle diffusion and dental enamel fluoride uptake
in comparison with fluoride toothpastes which contain
no such phosphate pellic].e penel:ration agents.
While rel.atively high levels of soluble phosphate
salts can provide fluoride pellicle penetration benefits
in fluoride toothpastes, the presence of such salts can
also diminish the soluhle fluoride s-tability of such tooth-
pastes during storage~ I~ has been surprisincJly discovered,
however, that such soluble phosphate salts can be included
: 20 in the sil1ca~containinq, fluoride toothpastes herein with
especially beneficial fluori.de compatibili-ty results if
the particular alkaliale earth metal treated precipi-tated
silica abrasives herein are employed.
- ~3 ~
33~
Phosphate sal-ts optionally present in the toothpaste
compositions herein are water-soluble. For purposes of this
invention a "water-soluble" phosphate salt is one which is soluble
in water -to the extent of at least 3.0 g/100 cc H2O at 20C.
The phosphates are those phosphorus compounds in the
anions of which each atom of phosphorus is surrounded by four
oxy~en atoms arran~ed at the corners of a tetrahedron. ~y shar-
ing oxygen atoms between tetrahedra, chains, rings and branches
polymers of interconnected PO4 tetrahedra can be realized.
Simple phosphates are orthophosphates. Polymeric phosphates
include the polyphosphates such as the pyrophosphates and tripoly-
phosphates. Ring phosphates are the metaphosphates.
Examples of suitable water-soluble polyphosphates for use
herein include tetrapotassium pyrophosphate, tetrasodium pyro-
phosphate, disodium pyrophosphate, sodium tripolyphosphate and
potassium tripolyphosphate~ Examples oE suitable water-soluble
metaphosphates include monopotassium metaphosphate, sodium tri-
metaphosphate, sodium hexametaphosphate, and sodium heptameta-
phosphate. Many of these water-soluble polyphosphates and meta-
phosphates are utilized in the form of hydrated salts.
The most preferred phosphate salts for use in the presentinvention are the simple orthophosphate salts. Orthophosphate
salts are derived from tribasic orthophosphoric acid of the
formula H3PO4. Water soluble sodium, potassium and ammonium salts
can be utilized.
There are about 10 different cr~lstalline sodium ortho-
phosphate salts including the various hydrates. These include,
p 2PO4, NaH2PO H2O, NaH2PO~-2H2O, Na H PO
2 4 2 ' 2HPO4 7H2O, ~a2HPO4 12 H2O, Na PO ~6H O
Na3PO4 8H2O, and mixtures thereof. Preferred sodium orthophos-
phates include NaH2PO4 H2O, Na2HPO4 2H2O and mixtures thereof.
24
3~
"~
Especially preferred are mixtures of NaH2PO~H20 and Na2HPO~
21120 in a weight ratio of monosodium to disodium salt within
the range of from about l:3 to l:5.
Potassium and ammonium orthophosphates can also be
utilized as pellicle penetration agents herein. E~amples of
such potassium and ammonium salts include KH2P04, K2HPO~,
K ~1PO4 2H20, K2~PO4-6H20, K3PO4 3H2 ~ 3 ~ 2 3
(N114)H2PO4, (NH~)2HPO4, ~N~)3PO~ and mixtures of -these salts.
An especially preferred phosphate salt mixLure for use
in thetoothpastes herein comprises a mixture of Na~l2PO~ H20 and
HPO4 2H20 in a weight ratio of sodium to potassium salt with-
in the range of from about l:3 to l:5.
The soluble phosphate salts of the present invention are
commercially available materials. A more detailed description
of such phosphate salts useful herein can be found in Kirk &
Othmer, En yc_oped a of Chemical Technology, Second Edition,
Volume 15, Interscience Publishers, Inc. (1968), pp. 232-276.
Preferably the ins-tant toothpaste compositions provide
from about 0.5 mole/lOOOg H20 to 2~0`moles/lOOOg H20 concentra-
tions of phosphate salts in the aqueous solutions which contactdental surfaces when the toothpastes of the present invention
are used in the mouth. Again, the supernatant from 3:l slurries
of water and toothpaste are used to simulate such use solutions.
Additional pellicle film penetration agents can also
optionally be added to the Eluoride containing toothpastes
of the present invention. Such optical in~redients further
enhance the fluoride pellicle penetration ~enefits provided
by the phosphate salts herein. Such agents include, for
- 25 -
' , ~ ,i .
example, hydroxy acids and salts thereof such as citric
acid, trisodium cikrate, malic acid and tartaric acid.
If present, such additional pellicle penetration agents
comprise from about 0.2 to 5.0% by weight of the tooth-
paste composition.
3) Flavoring A~nts
Flavoring agents can also be added to the instant
compositions. Suitable flavoring agents include oil of
wintergreen, oil of peppermint, oil of spearmint, oil of
sassafxas, and oil of clove. Sweetening agents which can
be used include saccharin, dextrose, levulose, aspartame,
D-tryptophan, acetosulpham, dihydrochalcones and sodium
cyclamate~ Flavoring agents are generally used in tooth-
pastes a~ levels of from about 0.01% to 2% by weight and
sweetening agents at levels of from about 0.05% to about
3% by weight.
4) Ant plaque/Anticalculus A~ent
Phosphorus-containing anticalculus agents and/or
bis-piguanide antiplaque agents can also optionally be added
to the toothpastes of this invention. Phosphorus-containing
anticalculus agents such as disodium ethane-l-hydroxy-l, 1-
diphosphonate and related materials are described more fully
in McCune et al; U.S. Patent 3,488,419, issued January 6,
1970. Bis-biguanide antiplaque agents such as chlorhexidine
(1,6-bis[M5-p-chlorophenyl-Ml-biguanido]hexane), the soluble
and insoluble salts thereof and related materials such as
1,2-bis(N5-p-trifluoromethylphenyl-Nl-biguanido) ethane are
described more fully in Haefele, U.S. Patent 3,934,002, issued
January 20, 1976; Haefele, U.S. Patent 3,937,807, issued
February 10, 1976; Procter ~ Gamble, Belgian Patent 843,244,
published December 22, 1976 and Procter & Gambl~, Belgian
Patent 844,764, published January 31, 19770
- 26 -
~1383~
, ~ .~
If present, the optional anticalculus and/or anti-
plaque agents generally comprise from about 0.01% to 2.S%
by weight of the toothpaste compositions herein.
5) ~ s and Coloring Agents, Misc.
A variety of other optional components well known
in the art may be added to the toothpaste compositions
herein to improve the usual aesthetics. These inclllde
pigments, dyes, speckles and the like. When present,
these optional components generally comprise ~rom about
lG 0.001 to abou~ 2~ by weight of the toothpastes herein.
~ ~ .
~;
;
;
- 27 -
3~
c~MposIrrIoM PREP~I~TION
Toothpaste compositions o the present invention
are prepared silnply by mixin~ together in any order and
any conventional means the essential and optional
components herein. O11Ce prepared, the compositions herein
provide a pEI of from about 4~0 ko 8.0, preerably
6~5 to 7OSj when said compositions are slurricd with
watex in a 3:1 weight ratio of water to composition.
Fluoride toothpastes providing pH values within the 4.0
to 8O0 range provide especially effective dental enamel
antisolubility benefits compared to toothpastes with
pH values outside this range Flavoring of toothpastes
wi~hin this pH range is also comparatively easy.
(:~OMPOSITION USE
Toothpaste compositions o~ the present invention
are used in conventional manner. 'rhe toothpaste compo-
sitions or slurries thereof are brushed onto dental sur-
faces and subsequently rinsed away.
During use of the toothpaste herein in conventional
manner, pastes or slurries generally contact dental sur-
aces ~or at least about 30 seconds. More pre~erably
such pastes or slurries contact dental surfaces Eor at
least about ~0 seconds.
.' , .................... . ..
,~ ..
~9~
The following examples are presentecl to illustrate
the present invention but it is not to be considered as
limitec'l ~hereto. In the ollowing examples, parts are by
we.ic3ht unless otherwise indicated.
S EXAMPLE 1
Into a 30,000 liter stainless steél reactc~r ja'cketed
o.r steam heating was added 1794 liters o sodium silicate
~olution (3~78 percent Na2O, 9.53 percenk SiO2) of specific
g.ravity 1~121 containing 42 grams of Na2O per liter~ The
; 10 reaction medium was heated to 88C~ ~ikh continuous agitationO
~t this point sulfuric, 10% concentration (specific gravi.ty
1.066) and sod]um silicate solution were added simultan-
eousl~ to the reaction medium at the`rate oE 151.4 l/min~
a.ci.d and 351 l/min~ sodium silicate while maintaining the
reaction temperature at 88C~ + l~C. These two solutions
were added to the reaction medium for a predetermined lenstl
o time. The silicate addltion was discon-tinued afker
7 minu-tes but the acid addition was continued until the
slurry pH was between 4~8~5.0~ The reaction slurry was
boiled at 100C~ for twenty minu-tes and the reac-tion p}l
was adjusted again ko between 4.8-5Ø The resultinc3 si.lica
slurry was filtered, and washed to remove most cf the reac-
tion by-product'(sodium sulfate) and thc filtcr ca~e was
dri.ed and the dry product milled tc the desi,red degree of
2~ fineness~ The dry silica was subjected to va.rious physical-
' ehemical tests and the analysis o which are set forth
hereinafter (See Table I). ~his example is prepara~ion of
con~xol product to which no alkaline earth metal is addea.
., .
~ 2g ~
3g[~
,
~N~IILl 2
l~lto a 30,000 liter stainless steel reactor jac~eted
fo~ am hea~ t3 ~Jas added 1734 liters of sodium si.licate
solutio~ (3~7~ percent Na20, 9.53 pexcent SiO2) o speci-
~;c gr~vi.t~ .l. containiIlcJ ~2 grams of Na20 per liter.
Tl~e rcac~io~l m~dium was h~ated to 8~C. with conti.nuous
~Igi~ation~ At this poin-t sulfuric, 10~ concentrati.on (spe-
Ci~iG CJraVity 1~ 066) and soclium silica~e so1.u~ion were added
silnultaneously to the re~ction mediulrl at the rate or lSlo 4
l/min. aci.d ~nd 351 l/minO sodium sili.cate while maintain-
. ing ~he reaction temperature at 88C~ C~ These two
so].utions were added ~o the reaction medium for a pred.eter-
milled lel~gth o time~ The silicate additioll ~as discon~inued
ater 47 rl~i.nutes bu~ the acid additi.on was continued until
~he slurry pH ~Jas between 4~8 - 5Ø The reaction s].urry
was bo.iled al~ 100C. for t~lcnty minu-tes and the reacti.on
pl~ was adjusted again to bet~een ~.8 ~ 5.0O Tlle resull:i.ncJ
~ silica slurry was iltered and washect to remove most o~ the
: reaGtion by-product (sodium sulate).
qlhe washed filter cake ~as then reslurri~d without
rater addi.tion at ambient temperature ~ith ac~itati.on.
While under ayitation, the slurr~ ~ras treated with 102
grarns o CodeY~ grade (U~SO p~lrity ood yrade) hydxatecl lime
(calcium hydro~i.de) to p~ovi.de 25 pprn of calcium ion treat~
Tnent based on t~he total weiyht of clry recoverable sol;d
product i.n the slurry form. ~fter treatment ~rith the
- Galcium ion, the ca~e slurry was agitated vic~orously `or
~ l~ minutes to provide the e~fectivc lcvel. o calcium ion
;~ trca~entonto-~lle surace of the silicon dioxide abrasive.
~}le res-~llti.llg prod~ct is then spra~ dried al. an inlet tc~-
peraturc of ~1~33Co and outlct temperaturc of 122C.,
millc~i alld char.actcri.~,cd or abrasi.vc ~In~ phy ;icc-l]. propcL-~
~i.cs i.ll tllc samc m~nncr a~; ~]~c al~L-asivc i.n l'.~;nltll?lC lo
:: :
l~X~l~PLE. 3 i ~ ,
The me~hod o~ tllis example was the same as in Example
2 except the rate o:E adclit;.on of sulEuric acid was at the
rate of 152.7 lit:ers per mi.nute and the calci.um addi~ion
was 204 cjrams of calci.um hydroxide which provides 50 parts
per mi.llion o~ calcium ion. The procluct was then charac- :
teri~edO
_X~lPL~ 4 ~ :
This e~ample was the same as E~ample 2 excep-t that
1~ the rate of addition of sul~uric acid was 166.5 llters per
minute and the calcium addition compr.ised 408 grams of cal-
~: cium hydroxide to provide 100 parts per million of calcium~ ,;
ion in the silicon dioxide. The product was then charac-
~-: terized.
~; ':
P8~MPLE S .:
: In this example, a dentifrice silica abrasive
was prepared by initially addiny 1420 ].iters o~ sodiurn silicate
solution (~.09 percent Na2O, 10.31 percent sio2) of specifi.c
gravity 1.131 containlng 46.3 grams of Na2O per liter to the
20 reactor as reaction medium. The reactor was heated to 91C.
wi,th continuous ayitation. At this point sulfuric acid, 126-
concentration (specific gravity 1.08) and sodi~m silicate
soluti,on were added simultaneously to the reaction medium at the
; rate o~ 162.7 .ljmin acid and 315.7 1/min sodium silicate while
maintalniny the reaction temperature at 91 ~ 1C. The silicate
addition was discontinued after ~7 minutes but the acid addition
was conti.nlled until the slurry p~ was between ~1.6-q,8. The
~ Jl -- .
reac~ion slurr~ was boiled at 100C~ for twenty minutes and
~he reaction pl-l was adjusted again between 4.6-4.~. The resultiny
silica slurry was filtered and washed to remove sodium sulfate
by-produc t .
The washed fil-ter cake was theII reslurried without
wa-ter addition at ambient temperature with agitation. While
under agitatioII the slurry was treated wiLh 510 grams of
Coclex grade (U.S. purity food grade) hydrated lime (calciurn
hydroxide) to provide 125 ppm of calcium ion treatment based on
the total weight of the dry recoverahle silicon dioxide abrasive
present in the slurry form. After treatment with the calcium
ion, the cake slurry was agitated vigorously for 15 minutes to
provide the effective level of calci~n ion treatment onto the
surface of the silicon dioxide abrasive. The resulting product
was then spray dried at an inlet temperature of 483C. and an
outle-t temperature of 122C., milled and then characterized. ;
EXA~lP~E 6
This example was the same as Example 5 except that 1608
liters of sodium silicate solution was initially charged to the
reactor as reac-~ion medium and the acid ra~e was increased to 170.3
l/min but the sillcate rate was maintained at 315.7 l/min.
The washed fi.lter cake was treated with ~16 grams of
calcium hydroxide to provide 200 parts per million of calcium ion
; treatment onto the sur~ace of silica abrasive. The product was
~,
then characterized~
EXAMPLE 7
This example was the same as Example 2 except that the
calciurn ion addition ~Jas 2,040 grams of calcium hydroxide to provide
S00 parts per million o-F calciurn ions. The product was then
characterized. ;
Ater preparation of the products of ExampleS 1 to 7
the~ ~ere characterized for physical properties and tlle results
are set ~orth in tlle followillg Table I.
3~?
rl
r I
o
o
a~
r-l ~
rl u~ O
~ O ~
w ~ o u-) ~g r l
O E; ~ 1 r~ O
h O ~
~ -rl ~
~c tO
~ _ r l ~r ~ r l o l (~
U~ ~ ~ ~ ~ ~ ~ ~ ~ h r l
m ~ 'I H
~ 'o ~ O
O ~
h .q ~
~¢ h
`
~1 ~1 o I
~ ,_ ~ ~1 ~
- rl ~1 1~) ~ O ~1 1~ 0 ~ O
~ O O O O O O O ~ ,~
h
O
H ¦ O ~ ~ o ~r r~
o~o (~
a '~ ~
~ * *
x o
Z
-- 33 --
83(;~
, , .
Several representative toothpastes of the present
invelltlon ar~ set forth in the fo}.lowing examples that
u~ilize the instant precipitated silica abrasives.
EX~MPLE 8
~ toothpaste is formulated utiliziny the ~recipi-
; . , tated silica abrasive of Exarnple 2 which has the follow-
ing composition: .
mount
; Componen-t .(Wt. ~)
Preci.pitated Silica Abrasive 160 0
(EY.ample 2)
Sodi~n Fluoridc (~aF) .. 0.28
`, Sorbitol Solution (70%) 32.0
Glyceri.n . 130 0
Sodium Carrageenan 0.75
Monosodiurn Orthophosphate Monohydrate 2.15
(NaH2PO~ H20)
Dlsodium Orthophosphate Dihydrate 8.34
~H~04 2~12o)
Sodium Alkyl Sulfate Solution (28.8%) 6.0
: Coconut Monoylyceride Sodi~ Sul~Eona-te 0.9
. Flavor 1.22
Sodi.um Saccharin 0.3
Color (F~G Blue #1 Solution 1%) 0~35
2S Ti-taniurn Dioxide (Tio2~ 005
Trisodi.urn Citrate Dihydrate 0.25
(C~;H5~1a307~ 2H20)
Distilled Water'~ . . q'S'
100. 0
Total
.
. , ~ 34 - ~~
831D .
~he above toothpaste compositi.on is prepared by
~dmi~ing the components thereof in the normal manner of
too}hpas-~.e pxeparcltior~. Pxefe.rably, the water component
is first added to a sultable conta:iner to which thereafter '
.is aclded ~ith moderate agitation, in order, the pellicle
~ilm penetratioII agents, the flavor, the humectant and
~he.reafter, the remaining components.
~ 3:1 weight slurry o the above freshly prepared
composition with water (3:1 is water to composition) pro-
duces a pH o about 7.1.
Such a toothpaste composition provides beneficial
~luoride treatment for dental tissue brushed therewith
due to the high toothpaste fluoride compatibility. The tooth-
paste also provides good cleaning and an RDA oE lOU. When
s~ored for prolonged periods of time at 80Fr. such a
toothpaste exhibits minim~l loss o soluble fluoride.
Toothpastesproviding substantially simi.lar ~luor-
ide treatment benefits, toothpaste 1uoride compatibility,
and cleaning per~ormance are realized when in the Example
8 composition, the sodium fluoride is replaced w:itll an
~qui~alent amount of stannous fluoride, sodium chlorofluor-
i.del potassium fluoride, potassium stannous fluoxide, lndium
;~luori.de, ~inc fLuoride or ammonium fluoride.
3~
~ oo~llpastes providing substantially similar fluoride
treatilletlt b~ne;.ts and substall~ially si.milar cleaning per-
form~ce a:re reali~ed when, in the Example 8 composition,
1;hQ. phospllclte salt mixture is repl.aced with an equivalent
C)Ill~ 0~ Na~l2Po~ aH2P04 H20~ MaH2P04~ 2H20~
'1~ 2~1P~ 2~I2lNa2HP04 71~120~Na3PO~'6H o
~ N~3Po~ g~i20; KH2P04~ K2HPO~r K2}~Po4D2}~20~
~ 4 I20l ~3P04 3H20- ~3P04-7H2or K3P0~ 9H20, (NH ) H PO
- ~Nil,~)2HPO~, tNH~)3PO~, other mixtures of NaH2PO~ O
and Na2IlPO~lo2H20 in monosodium to disodium weight ratios
o~ rom about 1 3 to 1: 5, mixtures o~ NaH2P04 H20 and K2HP04 2H20
in sodium to potassium salt weight ratios o~ from about
].:3 to 1:5, tetrapotasslum pyrophosphate, tetrasodium pyro-
~,
.i phosphate, disodium pyrophosphate, sodium tripolyphospha.te~
; 15 po-tassium tripolyphosphate, monopotassium metaphosphate,
~ ~ sodium -trimetaphosphate, sodi.um hexametaphosphate or sodium
; . hep-tametaphosphate; provided such composi tions provide a
3-1 slurry pH of from 4.0 to 8Ø
.;
3~
F.X~PLF, 9
A high abrasive level toothpaste is for~ulated
utilizing the p~eclpitated silica abrasive of ExaMple 3
which has the following compositionO
.
~mount
Component (Vwt~%)
Precipita~ed Sillca Abxasive 35.0
~Example 3)
8Odium Fluoride ~NaF~ 0o22
Glycerin 5.0
. Sorbito]. Solution ~70%~ .20.0
Carboxymethyl Cellulose 10.7 D.S.) O.S
Magnesium Aluminum Silicate (Veegum Flakes) 0.3
Monosodium Orthophosphate Monohydrate 0.3
(Na~l2PO~ H2O) 0 3
Disodium Orthophosphate Dihydrate
~Na2~P04 2H2)
Sodium Alkyl Sulfate Solution ~28.8%) ~-3
Coconut:Monoglyceride Sodium Sulonate 0.7
Flavor 0 9
Sodium 5accharin 0.2
Ti~anium Dioxide (TiO~) 0.5
Speckles 0.5
Distilled Water ~
Total - 100.0
~ - 37 ~
3~
Toothpastes providirl~ subst~ntially ~imilar ~luoride
~.reatment beneits, toothpaste fluo.ride compatibility~
and cleaning performance are reali~.ed when in the Example
9 compositi.on, the preclpita.ted si.li.ca abrasive componen~
5 ; prepared as in Example 3 is replaced with an equivalent
amount o~ abrasives prepared by Examples 2, 4j 5 and 6.
Toothpastes pro~iding substantially similar fluoride
treatment benefits and substant.ially sirnilar cleaning
performance are realized when, in the Example 9 composi-
tion, the phosphate salt mixtuxe is replaced with an equi
valent amount of NaH2PO~,NaH2PO~ H2O, NaH2PO4 2H2O,
Na2HPO~Na2HPo4 2H2O,Na2HPO4 7H~O,Na3PO4 6EI20
Na3po4~8H2o~ KH2PO4,~ K2EIPO~r K2 ~ 2
K~PO~ 6H2O, K3PO4 3~2~ I~3PO4-7H2O~ K3PO4 9H2O~ (NH4) H2P4
~N}i4)2ilPO4, (NH4)3PO~, other mixtures o Na}l2PO4 H2O
and Na2HPO4 2H2O in monosodi.~ to disodium weight ratios
of rom about 1:3 to 1:5, mixtures of Na~PO,1 H2O and K~HPO~2H2O
in sodium to potassi.um salt weicJht ratios of from about
1:3 to 1:5, tetrapotassium pyrophospha-te, tetrasoclium
pyrophosphate, disodium pyrophosphate, sodium -tripolyphos-
phate, potassium tripolyphosphate, monopotassium metapilos-
phate, sodium trimetaphosphate, sodium hexametaphosphate
or sodium heptametaphosphate, pxovidecl such compositi.ons
provide a ~:1 slurFy pE~ o~ from 4Øto 8Ø
,
-- 38 --
3~
.
EX~MPLE 10
A clear toothpaste is formulated utilizing the
precipitated silica abrasi.ve of Example 4 which has the
following composition:
Amount
Component ~Wt
Precipitated SiLica Abrasive 20.0
(Example 4)
Sodium Fluoride (NaF) ~24
; : 10 Sorbitol Solutian (70~) 57.0
Glycerin
,
Sodium Carrageenan 0.5
Phosphoric Acid (85~) 0.10
Sodiu~:Alkyl Sulfate Solution (28.8%) ~0
1 0
Flavor
Sodium Saccharin 0.2
Color (FD~C Blue ~1 Solution 1~) . 0.05
Distilled Water . ~ s.
' 100. 0
: !To~al
,
.
:
, .
- 39 -
.: ,
~ .
~P~i8~
EXAMPLE ll
~ low abrasive level toothpaste is formulated
util.izing the precipitated silica a~rasive of Example 3
which has the followiny composition:
Amount
Component (Wt. ~)
Precipitated Silica Abrasive 6.0
(Example 3)
Stannous Fluoride (SnF2) 0.40
Sorbitol Solution ~70%) 51.0
Glycerin 25.6
Sodium Carboxymethyl Cellulose (.7 DS) l.0
Sorbitan Monoisostearate 2.00
Sodium Alkyl Sulfate Solu~ion (28.8%) 6.0
Flavor 1.20
Sodium Saccharin 0.28
Color ~FD ~ C Blue #l Solution 1%) 0.25
Pyrogenic Colloidal Silica (Aerosil~ 200V)* 5.00
Distilled Water q.s.
Total lO0.0
*Marketed by Degussa, Inc.
- 40 -
: . . . .
-
3(P
Toothpclstesprovldiny subst.an-tially similar fluoxide
treatment henefits, toothpaste fluoride compatibility and
cleaning pexformance are reallzed when in the Example 10
composition, the precipita-ted silica abrasive component
5 prepared as in Ex~ple ~ is replaced with an equivalent
amount o abrasives prepared by Examples 2, 3, 5 and 6!
A toothpaste providing substantially similar fluor-
ide treatment benefits and an i,mproved anticalculus benefit
is realized when the Example 10 composition additionally
contains about 1.0% by weight of disodium ethane-l-hydroxy-l,
l-diphosphonate.
~9~38~(~
TE:STI~G ~ND EVALOATION
The precipitated silica abrasives herein can be used
- to prepare especi.ally desirable therapeutic toothpaste
compositions conkaining soluble phosphate pellicle film
penetration agents~ Such compositions provide both high
abxasive-fluoride compatibility and yet have ~ood tooth- cleaning performance~ The ollowing tests and evaluation
' serve~ to demonstrate ~le excellent fluoride compatibility
- provided by the precipitated silica dental abrasives herein
- ~o in the -toothpaste composition of the presen-.,t inventionO
It is also shown hereinbelow that abrasives o~ the present
: invention provide higher abrasive fluoride compatibility
., ~
than similarly prepared abrasives which have not been treated
,~ so as to contain the essential amounts of alkaline earth
material~ The excellent cleaning performance of the -tooth-
paste compositions herein is additionally demonstrated.
,: ~inally, it is shown herein that abrasives made from a
sulfate liquor acidulation process --even though contain-
: :- ing an al~aline earth material-- fail to provide the high
20 ~ fluoride compatibility values of the "resh water" preci-
pitated silica abrasives provided herein.
. Abrasive Fluoride Cornpatibility
.
Precipitated silica dental abrasives can be screened
for their relative compatibility with fluoride materials
by means o a 24 hr~ abrasive slurry test~ Such a test
can be used to generate-data which c,an predict the avail-
- ability o soluble fluoride in certain types of fluoride ~ ~h-pas~ after storage ovcr approximately a four~~eek period at 80l
The 2~ hour abrasive slurry test i.s us~,d to ~'enerate
fluoride compatib1lity values wllich are dc~incd as that per-
t - centa~e of theoretical maximum availablc ~luoride which is
- actu~lly mcasurcd a~tcr ~ hours as solublc ~luori.de by
thc following tcst mc~hod. In this n~ctl~od (Orion ~ccif.ic
, - 42 -
330
Ion ~lectrode Method) a standaxd sodium fluoride stock
solution containing 1624 ppm of fluoride is prepared by
dissolving 2.80 yrams of soclium fluoride, 21.5 grams of
Na}l2PO4 and 83.4 grams cf Na2HPO~ 2ll?0 in 672.5 grams of
deionized distilled ~ater and stored in a polyethylene
bottlc. Thirty (30) grams of this solution is then weighed
out. Seven (7) grams of the silica abrasive being tested
is then dispersed into the solution and contacted for 24
hours at a temperature of about 100~. (37.8C.). After
24 hours~ the precipitated silica abrasive/fluo~ide solu-
tion is centri~uged for 20 minutes at 15000 rpm or until
the supernatant is clear. Then 10 ml. of the supernatant
is pipetted into a plastic vial. Thereafter, 10 ml. of
EDTA/TT~AM solution is likewise pipetted into -the plastic
vial. (The EDTA/THAM solution is a 0.2 molar in EDTA
(ethylene diaminetetraacetic ~ acid, disoclium salt) and
0.2 molar in TH~M (2~Amino-2-hydroxymethyl-1,2-propanediol)
and ad~usted to pH 8.0 with sodium hydroxide.) ~ magnetic
stirring bar is added and gentle stirring is initiated.
~o The fluoride ion concentration is determined by direct
potentiometxy with the Orion fluoride electrode (Model
9S-09). Emf is converted to parts pex million (pp~n)
fluoride in the supernatant by means of a logarithmic
equation. The fluoride compatibility value is then cal-
~5 culated by expr1~ssing the measured ppm soluble fluoride
as a percentage of the theoretically available soluble
fluoride.
Using this method, the relative abrasive fluoride
compatibili~y values are determined for the several abrasives
prepared according to Examples 1 through 7. The results
of such evaluation are set forth in the follo~ing Table ~I.
~ 43
~ ~91~133~
l`A L~ II
~brasive Fluoride Compatibility
. Abrasive
Calclum Treatment Fluoride .
Example No. (ppm) _ . Compatibi~
~ .
1 (control) 76
2 25 93~
3 50 94%
.
4 100 ' 93%
125 91% -
.10 5
6 . 200 90~
8U~ :
.
' '
,
- ~ . ,............................... '
~ ; ' :
:, .
,
' ' ,
. .
.
.
' .
~ . .
: ~4 ,~
"
.
.. ,
I'he Table II data demonstrate that the precipitated
silica abrasives herein containing particular amounts of
an alkaline earth material provide markedly superior abra-
sive fluoride compatibility in comparison with that provided
by an al]caline earth-~ree abrasive material which is other-
wise similarly prepared. Thus, precipitatecl silica abra-
sives prepared as in Examples 2 through 6 should be suit-
able for realizing toothpastes containincJ Eluoride and
pellicle film penetration agents that demons~rate high
abrasive fluori,de compatibility.
brasive Fluoride Compatibility in Toothpa,stes
Preferred ,toothpastes herein containing precipitated
silica abrasives and pellicle film penetration agents are
evaluated for abrasive fluoride compatibility~ The tooth-
pastes which are prepared for evaluation have the compo-
sition of the toothpaste of Example 8 and differ onl~ in
the variation of the abrasive component.
. To decermine fluoride compatibility values for the
: - toothpastes tested; a soluble fluori.de determination method
:~ 20 is used which is similar to the method descri~ed above for
the determination of abrasive fluoride compati.bility values.
In this method, the toothpaste composi.-tions are stored for
a spe,cified length o~ time in a lami.nate tube. rrllereater~
15.0 grams o~ the composition is placed in a lO0 ml n heaker
and then 45.0 g~ams oE distilled water is added. The
mixture then is sti.rred to form a slurry in which the tooth-
paste is uniformly dispersed. The ~slurry i5 subsequently
centriEuged ~or 20 minutes at lS,000 rpm or until th,~.super-
natant is clear.
-- ~5
3~
Th~ supernatant is then treated as in the abrasive
fluoride compat.ibility determination method described
above. Solub.le fluoride concentration is similarly mea~
sured and an abrasive fluoride compatib.ility~value for
each toothpaste is similarly calculated. The toothpaste
fluoride compatibilit~ values of the respective toothpastes
evaluated are shown in Table III. The abrasives evalllated
are those prepared as described in Examples 1 through 7
above and characteri.zed in Table I aboveO
.
'
.
'
'' ' ". ' ..' ' '
, ' ' ~ . '
' ''' ,'
'- : ,
:
. " ' :' ' . '
' '
' " ' '' ' , " ' ' ' , ,.
.;
:
- 46 -
~' .
~98~3~
T~BLE III
Toothpaste Fluoride Compatihility
Toothpaste
Fl~ri~e
Abrasive Calcium Treatmen-t Compatibility
! (Example No.) ~ pm) _ (1 wk. 80F.)
~_ .
1 ~Control) 0 76%
. 2 , 25 99%
3 5 0 9 8.~i
' ~ 100 99%`
125 97
6 . 200 94
7 500 90
,
' ~ . .
~ . .
`'' ' .
. '
.
.
- 47 -
3~
The Table III clata demonstrate that ~he pre~erred
toothpastes herein whlch utilize the instant precipitated
silica abrasives provide superior abrasive fluoride compati-
bility values in comparison with that provided by a similar
too-thpaste composition COntaininCJ the non-alkallne earth
treated precipitated silica abrasive prepared by the method
of-Example 1~ The data of Table III further demonstrate
that the soluble fluoride avai.lability from the fluoride
ion source material is not significantly diminished upon
storage when the silica abrasives of the present invent~on .
ara employed in the preferred toothpastes herein.
Of course, it is to be recognized that the amount
of available soluble fluoride in even the toothpas-te com-
positions herein will decrease to some extent as a Eunction
o inc.reasing time and temperature of storage. Thus, tooth-
paste fluoride compatibility values for too-thpastes stored
for longer periods or at more severe temperatures are gener-
ally lower than those exemplified above.
Additional abrasive fIuoride ~ompatibili-ty dclta
for several toothpastes demonstrating storage for longe.r
periods ancl higher temperatures are shot~n in Table` IV o
: . ~ 4~
9~3
E~
~Sl oo ~D I I I ~ I CO
." ..
~ ~ I .
~ ~ ~ o~o
a)
h ~ '
n ¦
~ ~ o
H E~ 3 ~ o~ -C~ o~O
~ ,1
m
g ~ ~
: : ~ ~
~ ~ ~
¦
' ~, .
o
` :
g _
~ ._ .. .
31~33~
.,
The Table IV data.demonstra~e that the preferred
~oothpastes herein maintain their relatlvely high fluoride~
a~rasive compati.bility levels ~ven under prolonged stora~e
or under severe storage conditlonsO
l Cleaning Performance :
, The dental cleaning ability of the silica ab'ra-
sives herein can be estirnated by means o Radioactive
Dentin Abraslon (RDA) testin~3. RDA values can be used
to estimate the xelative cleaning perormance of various
- abxasives fQr any given type of dentifr.ice abrasive.
Thu~, for precipitated silica abrasives, an RV~ value
(measured by the method provided below) of at least 40,
prefera~ly between 70 and 120, is needed to insure that;
the abrasive has su~icient abrasi.vity to be an ef~ec-
tive dentifrice cleaner. Prior art precipitated si.lica
abrasives which do exhibit high toothpaste fluoride com-
patibility generally are poor cleaners for oral hyglene
purposes as evidenced by low RDA values. The'alkaline
-earth treated abrasives, however, provide both effective
.
:20 tooth cleaning and high fluoride compatibility.'
: ' Several commercial precipitated silica abrasives
; which demonstrate relatively high toothpaste 1uoride
compatibility as measured herein are selec-tecl for evalua-
tion for RDA values~ Testing is conducted within a standaxd
25~ toothpaste ma~rix having the composition of the tooth~aste
of Ex~mple 8, which d.iffers only in the variation of the
' abrasive component.
The method which is employed for determining the ~DA
. ~alues for toothpastes that are tabulated in Table V is
3~' described below. This test method is described more full~
in the Journal of Dental 1~esearch, July - August, 1976, by
~Seferren, pp7 563-573. 'l~he specific steps for determi.n-
ing RDA values are set ~o~h as follows-
- 50 -
.
, . . ....
3~
A. Selection and preparation of teeth
. _
Sound, single-rooted permanent teeth tlat are
caries-free and vital at extraction are selected. Teeth
are then scraped clean with a scalpel~ ~he crown and root
tip of each too~h are removed using an abrasive disc so
as to prepare a dentin sample 14 n~ long and at least
2 mm wide at the narrower end. Cut pieces of root ~dentin
chips~ or, alternatively, an additional tooth,are also
prepared to be later used in determining a correction
factor for self~absorption o~ radiation.
B~ Irradiation of dentin
. The prepared roots and dentin chips described in
Step ~ are exposed to a neutron ~lux of 2 x 101 neutrons/
cm2 for three hours.
C Mountiny_of roots
~, .
After irradiation, the irradiated roots are embeded
in a mount of cold-curing dental methacrylate resin and
mounted onto a cross-brushing machine. Too~hbrushes used
throughout the test are 50-Tuft, mediuml flat~ "Pepsodent"~
toothbrushes.
D. ~reconditionin~ the dentin surfaces
Prior to initial test run, the freshly mounted,
irradiated roots are brushed with a reference slur~^y
(l~g calcium pyrophosphate ~ 50 ml of a O.5% CMC-10~
. glycerine solut~on) for 6,000 brush strokes. At tlle
: beginniny of each subsequent dayls test run, t'~e roots
are brushed for 1,0~0 strokes.
:.
- 51 -
~ 3
~ . !
.,
"" ~. ' ' .,
3~
E. Test run
Ater precondi-tioning, the dentin samples are then
conditionecl wi.th the reference slurry (same slurry as in
Step D) fox 1,500 brush strokes at the beginning, during
and end of each test runO The test run consists of brush-
. ing dentin samples or 1,500 brush strokes with a slurry
of test product (25g denti.fri.ce -~ 40 ml deionized of
distilled water).
F. Preparation o~ correction factors
.The correction factors are prepared by dissolving
the dentin chips or, alternati~ely, an additional tooth,
from Step B in 5 ml~ conc. HCl brought to a volume of
250 ml. with distilled water. One ml~ of this solution is
~ added to test pastes and reference slurries which are pre-
pared similarly to those in Step E, and then neutrallzed
with 0~1 N NaOH.
Radioactive Tracer Countiny
The radioactivity of the slurry sarnples (1.0 ml.)
.
is determined with an I~tertechnique SL-30 liquid scintil-
lation counter~ Alternate counting procedure: 3 ml. ali-
quots of each slurry are transferred to stainless steel,
flat-bottom 1 inch x 5/16 inch planchets and counted using
Nuclear Chicago Geiger Counting System~
Calculations
~5 l`he radioactive dentin abrasion value (RD~) for
a particular paste will be the ra-tio of the average cor-
rected counts or that paste to the average count or
the reference multiplied by 100. The reference abrasive
is yiven an arbitrary dentin abrasion value o 100 units.
The results of such ~A value determination are set
for-th in the following Table V.
, ' ' ' .
- 52 ~
3~
TABLE V
Radioactive Dentin Abrasion Values
Toothpaste Fluoride
Compatibility
Abrasive RDA One Week (80UF)
A. (Example No.)
1. Control 75~7 76%
2. 80~21 99%
3~ 67-8 98%
4. 80+1 99%
5. 103~5 97%
. 111-5 9~%
7. 56+4 90%
B. Commercial Precipitated
S.ilica Products
8. Sident~ 3 1. 14~2 92%
9. Neosyl~ 2- 25-2 78%
10. QUSO~ G-30 3' 22-2 87%
11. Neosyl~ ET ' 26-4 84%
1. A precipitated silica marketed by Degussa, Inc. (N.Y.C.).
2. A precipitated silica marketed by Joseph Crosfield & Sons,
Ltd. (London, England).
3. A precipitated silica marketed by Philadelphia Quartz Co~
(Valley Forge, Pa.).
4. A precipitated silica marketed by Joseph Cros~ield & Sons
Ltd.
:~`
''
- 53 -
3~
The Table V data demonstrate that commerclal pre-
cipitated silica abrasives may well demonstrate high abrasive
fluoride compatibility but are not sufficiently abrasive so
as to be useful as dentifrice abrasives. Surprisingly, the
instant novel precipitated silica abrasives provide outstand-
ing abrasive fluoride compatibility yet simultaneously provide
excellent RDA abrasivity values, which values can be used as
an indicator of relative dental cleaning performance.
"Fresh Water" versus "Sulfate Li~uor" Abrasives
As indicated hereinabove the abrasive products of the
present invention are related to but distinctly different from
the calcium treated silicas of U.S. Patent 4,159,280. To
demonstrate such a difference, the following evaluation is
made to compare the fluoride compatibility of the products of
U.S. Patent 4,159,280 with that of the abrasive products of
this invention. The "sulfate liquor" silicon dioxide materials
tested are prepared in accordance with the process disclosed in
U.S. Patent 4,159,280 and U.S~ Patent 3,960,586, issued June 1,
1976, by the following procedure- ;^
Dry sodium sulfate was added to 10.0 gallons of
water in a 200 gallon reactor so that the sodium sulfate
concentration in the reaction medium was 10%~ The pH of
the reaction ~edium was then adjusted to 9.0 by the addi-
tion of sodium silicate. The reaction temperature was 65C.
(150F). The sodium silicate solution had an SiO2/Na2O
mole ratio of 2.5 and a concentration of 2.0 pounds per
gallon. Sodium silicate was added to the reaction medium
for 4 minutes. At this point the sodium silicate addition
was stopped and sulfuric acid of 11.4% of concentration was
added to the reaction medium until the pH of 9.0 was reached.
At this point the sodium silicate solution and the sulfuric
- 54 -
._
3~
acid solution were add~d simultarleously for a period oE
35 minute~. A-t -the end of the 35 minute period of silicate
acl~i.tion, the silicate was discontinued and the acid addi-
tion was continued until a slurry pH oi 5.5 was obtained.
The batch was digested at 77~C. for 20 minutes
and the resulting wet cake recovered and washed.
The wet cake was then treated in the manner describ-d
Eor Example 2 of this applica-~i.on, divided into six separate
portions and t.reated respectively with 50, 100, 200, 400 and
800 parts per million of calci~n from aqueous solutions of
calcium hydroxide. Each wet cake was then dried and
processed as described for Example 2 and characterized
in the following Table VI whexe the first ahrasive is a
control in which no calcium was added. Table VI se-ts forth
the resul-ts of such evaluation.
- 5S
3~
TABLE VI
Abrasive
Ca Addition Fluoride
"Sulfate Liquor" Abrasive ~ppml Compatibility*
A O (control) 88
B 50 89
: C 1~0 , 8~
D 200 88
E 400 86
F 800 82
*Determined by test descrihed for rrable II.
As can be seen rom the Table VI data, the calcium
treated "sulfate liquor" abrasives of U.S. Patent 4,159,280
provide abrasive fluoride compatibility values which are
generally lower than those provided by the "fresh water"
silica abrasives of the present invention (See Table II).
Furthermore, the addition of an alkaline earth metal to
abrasives made by the "sulate liquor" method does not
result in a dramatic improvement in abrasive fluoride
compatibility~ Conversely, as can be seen from a comparison
of Table II, the addition of equivalent amounts of alkaline
ear~h metal to the silica abrasives herein made by the
"fresh water" method does result in dramatic improvements
in abrasive fluoride compatibility.
~ 56 ~
