DE2065824A1 - FLUORALUMINUM SILICATE GLASS POWDER AND ITS USE FOR SELF-HARDING MEDICAL CEMENT COMPOUNDS - Google Patents

Description

Description of the patent application

NATIONAL RESEARCH DEVELOPMENT CORPORATION Kingsgate House, 66-74 Victoria Street London, England

concerning:

Fluoroaluminosilicate glass powder and its use for self-setting medical cement compounds

Cement compounds for medical purposes are used in a variety of ways, e.g. instead of plaster of paris or glue bandages. In dentistry in particular, they are used as filling material for teeth, for cementing inlays and crowns, as the basis and / or lining of a tooth cavity, for. temporary fixation and connection of dental regulating devices with the teeth as well as for closing root canals after a root canal treatment. The known Silicate tooth cement is considered the most important, despite its disadvantages Material considered for repairs to the front teeth. Since it is translucent, it can be adjusted to that its color corresponds to the enamel of the tooth to be treated. It is also abrasion resistant and possesses high compressive strength. Its disadvantages are that it irritates the pulp tissue because of its alkalinity can, which is why it is necessary to first

609812/0920

-Z-

clothe before the cement paste is poured in. This cement is also quickly washed out by acids in the mouth and it tends to change color significantly over time. The 2 & nentmasses based on zinc oxide are also used. This metal oxide powder hardens to a solid product through a reaction with high-percentage aqueous phosphoric acid. However, because of its acidic character, zinc phosphate cement also has the disadvantage of being able to cause pulp irritation.

From GB-PS 1,139,430 self-curing cement compositions have become known, the powder and about 40% aqueous solutions of polymers of acrylic acids, particularly polyacrylic acid and its copolymers are obtained by mixing zinc oxide of W. The carboxylate cement mass obtained by the reaction of the zinc oxide with polycarboxylic acid in the presence of water has good adhesive strength, but after curing leaves something to be desired with regard to compressive strength. There is therefore a need for a cement powder which optimally combines the advantageous properties of the known carboxylate cements with a high compressive strength of the hardened material.

It has now surprisingly been found that a new h Fluoraluminiumsilicatglas composition, wherein the weight ratio of silica to alumina according to the invention 1,5 - 2 and the weight ratio of fluorine to alumina from 0.6 to 2.5 or wherein the weight ratio of silica to alumina 0 .5-1.5 and the weight ratio of fluorine to alumina is 0.5-2.0, is an improved material for a carboxylate cement paste after pulverization. By mixing the powder with an aqueous solution of a medically compatible polycarbonate

609 812/092 0

acid polymer based on polymers of acrylic acid, this polymer should have a relative viscosity of 1.05 to 2.0, a self-hardening cement paste is obtained which, after hardening, shows particularly high compressive strength values. The relative viscosity of the polymer is the viscosity measured with a capillary viscometer with a 1% (weight / volume) solution of the carboxylic acid polymer in 2η sodium hydroxide solution at 23% , based on the viscosity of the 2η sodium hydroxide solution.

The fluoroaluminosilicate glass powder of the present invention is reactive; by mineral acids, e.g. hydrochloric acid it decomposes. It reacts with the carboxyl groups of the polymer in the mixing liquid in a similar way to the zinc oxide in the known ones Carboxylate cement masses within a period of about 1.5 to 10 minutes after mixing to form a solid mass.

The mixing liquid should be the carboxylic acid polymer in one Contain an amount of about 20-60% by weight.

For practical use, it is recommended to use the new fluoroaluminosilicate glass powder together with that of the carboxylic acid polymer containing mixing liquid in a pack separately from each other available to the consumer. According to the invention, the weight ratio in the pack should from powder to solution in the 2 parts are preferably 0.5: 1 to 5: 1. When these two pieces of packaging are mixed with each other, you then get the self-hardening plastic cement mass, which then within a Cures for a maximum of 10 minutes. With another Pack, the powder can be contained in a special capsule, with the total amount of powder in the pack and the Total amount of liquid in the pack in the desired ratio. With another pack form, the both ingredients in the same capsule in the desired one

609 812/0920

Relationship lie. In a further pack form, the two ingredients can be in the same capsule in the desired one Ratio must be included provided facilities are in place to avoid premature response.

In these packs, which are particularly advantageous in practice, the amount of glass powder is 15 to 85% by weight, of carboxylic acid polymer 3 to 50% by weight and of water 5 to 70% by weight of the total mass obtained therefrom by mixing.

Compared to the known cements based on zinc oxide £ and polyacrylic acid is used when using the cement combination according to the invention twice as high compressive strength of the hardened mass obtained, which is translucent in contrast to the opaque, cloudy zinc oxide cement.

The new fluoroaluminium-silicon.cat powders can be produced by mixing mixtures of silicon oxide (SiOp) , aluminum oxide (Al ₂ O,), cryolite (Na ^ AlFg) and fluorite (CaFp) in the appropriate quantities at temperatures of more than 950 C melts together. The preferred melting temperatures are in the range from 1050 to 1350 ^° C. After melting, the glass is poured out and quickly cooled, for example in air or water or a combination of air and water. The proportions of the various elements in the glass generally correspond to the proportions of the same elements in the mixture before melting. However, some fluorine can be lost during the reaction, for example up to 20% by weight, which should be taken into account When determining the proportions of the reactants for the mixture to be burned. The fluorine loss depends on the time that the glass is kept at the melting temperature. In order to keep the fluorine loss as low as possible, the glass should be heated as briefly as possible Times of 30 to 120 minutes are preferred.

The exact content of fluorine in the glass can be determined by the method of A.C.D. Newman in Analyst 1968, Volume 93, Page 827

6098 12/0920

It is not necessary to determine the amounts of aluminum oxide and silicon oxide in the glass, since there is no noticeable loss of these components during the reaction. Consequently, the amounts of silicon oxide and aluminum oxide in the glasses according to the invention correspond to those of SiOp and AlpO, in the mixture before the melting reaction .. Various changes in the composition of the fluoroaluninium compounds can be made within the scope of the invention. For example, it is often advantageous ^{to add aluminum fluoride (Ali 1} -,) and aluminum phosphate (AlPO.) to the mixture of aluminum fluoride to aluminum oxide in the mixture is preferably 0 to 1.0 and the weight ratio of aluminum phosphate to aluminum oxide is also preferably 0 to 1.0 The fluoride can be partially or completely replaced by lanthanum fluoride (LaF.,), magnesium fluoride or both The alumina can be partially replaced by another oxide Elements of the. Group III titanium dioxide or zirconium dioxide can be replaced. The cryolite can be completely or partially replaced by mixtures of lithium fluoride and aluminum fluoride. Two preferred groups of fluoroaluininosilicate glasses that can be used in the present invention were made by fusing together mixtures of the following compositions:

Al ₂ O ₅ SiO ₂ total metal fluorides calculated as fluorine

AlF ₃ AlPO ₄

I. - 190 II 100 100 - 150 100 150 160 100 75 - 100 105 125 50.00 125 0 - 150 0 - 100 0 - 0 - 0 - 50 -

609812/0920

The following are particularly suitable mixtures for Manufacture of such glass masses indicated :.

(ι) (ii) (iirr (IV) (ν) (VI) (viii (viii) (ix) (x)

SiO ₂ 176 176 175 175 175 176 95 95 95 95 95 ^A1 2 ° 3 100 100 100 100 100 90 100 100 100 100 100 TiO ₂ - - - - - 10 - - - - - Na ₃ AlF ₆ 135 135 - 30th 65 135 76 76 76 76 76 CaF ₂ 87 87 240 207 168 87 56 56 56 - - MgF ₂ - - - - - - 45 - · LaF ₃ - - - - - - - - - - 94 AlF ₃ I. ■ 32 32 32 32 32 32 - · - 96 96 - 1
AlPO ₄ j 56 100 60 60 60 56 73 121 73 73 73

The degree of unity of the powder should be chosen so that when mixed with the chosen liquid a smooth Cement paste is created that hardens in a clinically favorable time. Preferably the grain size of the powder should be less than 0.1 mm and more preferably less than 0.04 mm.

The medically acceptable water-soluble carboxylic acid polymer has a relative viscosity as defined above from 1.05 to 2.0 and it has been found that the relative viscosity range given above has an average Molecular weight of 1500 to 150,000 corresponds to that according to the method indicated by Sakamoto (Chemical Abstracts 58, 13160c) has been determined.

The preferred carboxylic acid polymers are those obtained by homopolymerization and copolymerization of unsaturated

B 09812/0920

ten aliphatic carboxylic acids and copolymerization of these acids with other unsaturated aliphatic monomers such as acrylamide and acrylonitrile have been obtained. Particularly preferred are the homopolymers and copolymers of acrylic acid. Although carboxylic acid polymers with a relative viscosity of 1.05 to 2.0 are readily soluble in water, the concentrations and molecular weight should be chosen so that a solution is obtained which is not too highly viscous, otherwise a problem with the drawing of threads will arise when the desired amount of the solution is removed from the container and mixed with the glass powder. A concentration range of 40 to 55% by weight and a relative viscosity of 1.10 to 1.60 are preferred to produce a good cement. Particularly preferred cements can be made using concentrations of 44 to 52 % of a polyacrylic acid having a relative viscosity of 1.20 to 1.30. In choosing the appropriate concentration and molecular weight combinations, it must be borne in mind that stronger solutions of any particular polymer will be more difficult to mix and weaker solutions will result in lower cement strength.

The cements according to the invention should be produced in the usual way immediately after use. For this the substances from the one-part or multi-part pack are brought together and mixed to form a plastic mass, the in the short time in which the mixture has its plastic properties, then poured into a casting mold or on other way can be brought into the desired shape. For example, a certain amount of the polycarboxylic acid solution, sufficient to produce a small amount of cement, sufficient with a dental spatula or similar instrument removed from their packaging container or pushed out of a tube or similar container. This solution can then be mixed with a certain amount of the glass powder of the pack on a suitable surface will. The ingredients can be very quick

609812/0920

be mixed together to form a uniform coffin that starts to harden in a few minutes, and in general hardens within 10 minutes of mixing.

Raising the other parameters given above are the curing speed and the strength of the final product determined by the ratio of powder to liquid, which should preferably be as high as possible, as far as one can still is given a suitable processing time. The best ratio for a given powder and liquid can easily be determined by preliminary tests. Too little or too much powder usually results in a mixture that more difficult to bring into the desired shape. Particularly good results have been obtained with powder-to-liquid ratios from 2 to 3? 1 received. With a careful choice of powder and liquid one obtains a suitable plastic one A mass that hardens in a convenient time.

The carboxylic acid polymer solution used in a preferred method of the invention is by any of the usual polymerization processes. For example, the polymerization can be in aqueous Solution can be carried out in the presence of ammonium persulfate and various chain transfer agents, with solutions arise that contain up to about 30> of the polymer, This solution can then, if necessary, be concentrated to obtain a more viscous solution, or they can be freeze dried to give a solid, finely divided carboxylic acid polymer to manufacture.

Various other acrylic acid monomers can be included in the polymerization system to make carboxylic acid copolymers produce that have modified properties, provided that the carboxylic acid copolymer in water / water is sufficient is soluble, and with a fluoroaluminosilicate powder

609 812/0920

responds in the required manner.

The invention is further illustrated by the following examples explained *

example 1

The following ingredients were mixed by grinding together and then heated in a crucible to sillimanite 11QO ⁰ C, until the mixture became homogeneous (about 2 hours).

SiO ₂ 1000 g

Al ₂ O ₃ 618 g

Na ₃ AlF ₆ 73Og

AlPO ₄ 303 g

470 g '174 g

The resulting opal glass was rapidly cooled and dried and then mashed until a sample when using a 45% aqueous polyacrylic acid solution (relative viscosity 1.24) in a powder-to-liquid ratio of 3.1 J 1 was mixed, a curing time of 3 1/2 to Gave 4 1/2 minutes. It was made with a bpaüel on one Glass block mixed.

A lot of cement was made by mixing the crushed glass with a 50 ounce (weight by weight) Solution of polyacrylic acid (relative viscosity 1.24) with a powder-to-liquid ratio of 3.1! 1 manufactured. The cement had the following properties.

a) Hardening time: 3 3/4 minutes (determined with a 0.45

Gilmore needle at 37 ⁰ C).

- 10 -

6098 12/0 92 0

- ίο -

b) Compressive strength after 24 hours at 37 ° C: 10o2 kg / cm

(15 450 psi)

c) Acid resistance: The surface of the cement was initially

Protected for 24 hours and then remained after being exposed to an acid (pH = 4.0) for 24 hours was in touch, shiny and smooth. A common silicate that treats similarly became dull and powdery.

d) Resistance to discoloration: The cement shows a much greater resistance

Resistance to discoloration from tea, which is typical of one naturally occurring discolouring substance ^ than a common silicate cement.

Example 2

The following compounds were mixed by grinding together and then placed in a sillimanite crucible Heated at 1150 C until a homogeneous mixture was formed (approx 2 hours).

SiO

Νβ, ΑΙΡ, -3 b

AlPO ₄

AIP

175 g 100 g

30 g

60 g

207 g 32 g

The opal glass was produced according to Example 1 and mashed until it passed through a 0.04 mm (350 mesh) mesh. The glass possessed a plus of 21.6? 6 (theoretically $ 22.8 if no fluorine would be lost in the reaction).

-1t: -

609 8 12/0 920

By mixing the crushed glass with a 50% (weight by weight) aqueous solution of polyacrylic acid (relative viscosity 1.34) with a powder-to-liquid ratio of 3: 1 a cement was produced. The cement had the following properties:

a) Hardening time: 4 3/4 minutes (with a 0.45 Gilmore needle

at 37 ⁰ C).

b) Compressive strength after 24 hours at 37 ^° C.: 1935

The acid resistance and discoloration resistance were the same those of the cement of Example 1.

Example 3

■ The following ingredients were mixed by milling and then heated for 2 hours at 110o C ⁰ in a sillimanite crucible.

SiO ₂

Including _{3 AlF 6} AlPO ₄

176 G 100 G 135 G 56 G 32 G 87 G

The resulting opal glass was produced according to Example 1 and crushed until it passed through a sieve with a clear glass width of 0.04 mm. The glass had a fluorine content of 21.595 ». F / Al ₂ O ₃ 1.26 (theoretical amount if no fluorine had been lost in the reaction 23.4 '/ ° FAl ₂ O ₃ 1.38) «

It made a lot of cement by mixing the powdery Glass with a 41% (weight per weight) aqueous solution of polyacrylic acid (relative viscosity 1.24)

- 12 -

60 98 12/0920

with a powder-to-liquid ratio of 3: 1.

The client possessed the following properties:

a) Hardening time: 3 1/4 minutes (with a 0.45kg Gilmore needle

at 37 ⁰ C)

Id) Compressive strength after 24 hours "at 37 ^° C.: 1550 kg / cm ²

(22,000 psi)

The acid resistance and discoloration resistance were the same those of the cement according to the example

Example 4

The following ingredients were mixed with one another by grinding and then ^{heated to 120O 0} O for 2 hours in a Sillimanit crucible.

SiO ₂ . 95 g

Al ₂ O ₅ 100 g

76 g

56 g

73 g

The opal glass was produced according to Example 1 and crushed until it passed through a sieve with a mesh size of 0.04 mm. The glass had one Fluorine content of 16.2 ^ o (theoretically 175 *, if there is no fluorine in the lieaktion 'would have been lost).

It became a cement mass by mixing the glass powder with a 50% (weight by weight) aqueous solution of polyacrylic acid (relative viscosity 1.24) a powder-to-liquid ratio of 2: 1. The cement had the following properties:

'■ -13, -

609812/0920

Hardening timeϊ 3 1/4 minutes (with a 0.4 kg Gilmore needle

at 37 ⁰ C)

' ^On - 1670 kg / cm ²

(23 700 psi)

The acid resistance and the discoloration resistance were equivalent those of the cement according to Example 1.

Compressive strength after 24 hours at 37 ^W C: 1670 kg / cm '

Example 5

In this example, the production of a dental cement using a glass powder according to the invention and a Copolymers of acrylic acid and acrylamide described.

200 ml v / ater and 2.5 g ammonium persulfate were in placed in a flask, heated to 80 to 84 C and continuously degassed with nitrogen. Within 2 hours were the following solutions added:

a) 80 ml of distilled acrylic acid, 20 g of acrylamide

100 ml of water

20 ml isopropanol

b) 60 ml of water

2.5 g ammonium persulfate

after the addition was complete, the solution was further Maintained at 80 to 85 ° C. for 2 hours and flushed with nitrogen. The solution was then concentrated to the point where it polymerized Acrylic acid or 51 ^ total solids. The copolymer had a relative viscosity of 1.26.

The concentrated liquid, when mixed with the glass powder of Example 2 in a weight ratio of 3 * 1 was mixed, a dental cement with good physical Properties.

- 14 609812/0920

Example 6

The procedure of Example 5 was repeated using 20 g of acrylonitrile in place of the acrylamide. The solution was concentrated to such an extent that it contained 46 to ΑΊ ° / ° polymerized acrylic acid or 5b? » Contained total i ¹ est substances. The copolymer had a relative viscosity of 1.26.

The concentrated liquid yielded when used with the Glass powder of Example 2 in a weight ratio of 3: 1 was mixed, a dental cement with good physical Properties.

Claims

- 15 609812/0920

Claims (11)

Claims '■ 1. Fluoraluminiumsilicatglaspulver with a weight ratio of silica to alumina of 1.5 ms 2.0 and a weight ratio of fluorine to aluminum oxide of 0.6 Ms 2.5 or with a weight ratio of silica to alumina of 0.5 ms 1, 5 and a weight ratio of fluorine to alumina of 0.25 Ms 2.5. 2. Glass powder according to claim 1, characterized in that the glass also has some phosphorus oxide contains, wherein the ratio of aluminum phosphate to aluminum oxide can be up to 1.0. 3. Glass powder according to claim 1 or 2, characterized in that it has a grain size of less than 0.104 mm. 4. The method for producing the glass powder according to claims 1-3 by melting the glass component at a temperature of more than 95O ⁰ C, preferably, 1050 to 1350 ⁰ C, cooling the melt and pulverizing, characterized in that starting from a mixture of the following composition SiO ₂ Total metal fluoride
calculated as fluorine AlF AlPO Na 100 160-190 105-150 0-100 0-125 0-150 609812/0 920 5. The method according to claim 4, characterized in that that one starts from a mixture of the following composition Al ₂ O ₃ 100 SiO ₂ 75-100 Total metal fluoride calculated as fluorine 50 - "150 AlF ₃ 0-100 AlPO ₄ 0-125 Na ₇₅ AlF, - 50 - 100 6. The method according to claim 4 or 5, characterized in that one starts from a mixture in which the fluorite completely or partially by lanthanum fluoride and / or Magnesium fluoride is replaced. 7. The method according to claim 4-6, characterized in that one starts from a mixture in which partially replacing the alumina with another oxide of a Group III element, titania or zirconia is. 8. Use of the fluoroaluminosilicate glass powder according to claims 1-3 together with a medically acceptable water-soluble carboxylic acid polymer based on polymers of acrylic acid with a relative viscosity of 1.05 to 2.0 for the production of a self-hardening medical cement mass. 9. Use according to claim 8 in an amount of 15 to wt .-% of the fluoroaluminosilicate glass powder together with up to 50% by weight of the carboxylic acid polymer and 5 to 70% by weight Water based on the total weight. 60981 2/0920 10. Use according to claim 8-9, wherein the carboxylic acid polymer is in the form of an aqueous 20 to 60% by weight, preferably 40 to 55% by weight, solution. 11. Pack for use according to claim 8-10, characterized in that the fluoroaluminium sileate glass powder and the water-soluble carboxylic acid polymer, optionally in the form of the aqueous solution, in separate
Containers are available. 609812/0920