| WO/2022/112886 | CURABLE DENTAL COMPOSITIONS AND USES THEREOF |
| WO/2000/021489 | DIMENSION STABLE BINDING AGENT SYSTEMS |
| JP7422994 | dental curable composition |
JIANGUO LI (SE)
| DE3934008A1 | 1990-04-12 |
CHEMICAL ABSTRACTS, Volume 107, No. 2, 13 July 1987, (Columbus, Ohio, US), PROSSER, H.J. et al.: "The cement-forming properties of phytic acid", see page 358, abstract 12872b; & PHYTIC ACID. SYMP. "APPL. PHYTIC ACID", 1986, (), 291-302.
| 1. | A tooth filling material, particularly for a temporary use, composed of two components, which have been com¬ bined and reacted with each other, c h a r a c t e ¬ r i z e d in that one of the components (A) is pulveru¬ lent and mainly is composed of a first powder, which is in its turn mainly composed of zinc oxide, and a second powder, which is a filler material, which is composed of one or several ceramic materials, which are chemically stable in relationship to phytic acid, in that the second component (B) is in a liquid state and is composed of 35 55 % phytic acid, the rest being mainly water, in that the material after a careful mixing of the two components with each other is hardened in 210 minutes, and in that the compressive strength of the hardened material is 35 55 MPa. |
| 2. | A material according to claim 1, c h a r a c t e ¬ r i z e d in that the first powder has a grain size (sieve size) < 10 u , and in that the main portion of the se¬ cond powder has a grain size (sieve size) of at least 25 um and not more than 125 u . |
| 3. | 3 A material according to claims 1 or 2, c h a r a c ¬ t e r i z e d in that said second powder is composed of one or several calcium phosphatebased materials and/or one or several metallic compounds , which do not react with phytic acid, e.g. metal oxides, metal nitrides, me¬ tal carbides and/or metal borides. |
| 4. | A material according to claim 3, c h a r a c t e ¬ r i z e d in that said metal compounds belong to the group A1203, TiO, Zr02, Si02, SiN och SiC. |
| 5. | A material according to any of claims 14, c h ¬ r a c t e r i z e d in that said second powder mainly is composed of the calcium phosphatebased material. |
| 6. | A material according to claim 5, c h a r a c t e ¬ r z e d in that the calcium phosphatebased material " is composed of one or serveral of hydroxyl apatite, Cag(P04)30H, tricalcium phosphate, CajPO.)2, dicalcium ortophosphate, CaHPO., calcium biphosphate, Ca(H2P0.)2 and fluor apatite Ca5(P04)3F. |
| 7. | A material according to claim 6, c h a r a c t e ¬ r i z e d in that said second powder mainly is hydroxyl apatite. |
| 8. | A material according to any of claims 17, c h a ¬ r a c t e r i z e d in that said first and second compo¬ nents are added in an amount ratio A/B, which satisfies the expression 4 > A/B >1.5, the amount of component A being expressed in grams and the amount of component B being expressed in millimeters. |
| 9. | A material according to any of claims 18, c h a ¬ r a c t e r i z e d in that the pulverulent component A also contains 15 % lubricant, preferably in the form of one or several polymeric surface tensionreducing sub¬ stances. |
| 10. | A material according to any of claims 19, c h ¬ r a c t e r i z e d in that the amount of phytic acid in component B is 4555 %. |
| 11. | A material according to claim 1, c h a r a c t e ¬ r i z e d in that the first powder besides ZnO also con¬ tains MgO, and in that for the ratio MgO/ZnO : 01 < MgO/ZnO < 1, preferably 0.2 <MgO/ZnO < 0.8. |
Technical field
The present invention relates to a tooth filling material, particularly for temporary use, composed of two compo¬ nents, which have been combined and reacted with each other.
Background art
Materials which are composed of zinc oxide and eugenol are conventionally used as temporary tooth filling mate¬ rials or materials for preparatory treatment when apply¬ ing gold crowns, porcelain inserts and plastic fillings. However, eugenol has several drawbacks. It seems to be toxic to some extent, it adheres to the dentine and it is difficult to remove it. Also, it is absorbed to some ex¬ tent in the dentine and thus it interferes with the poly¬ merization process in connection with the application of a permanent plastic filling, which may easily result in a loosening of the plastic filling. Consequently, several different tooth filling materials have been developed, which do not contain eugenol and which are designed for either a temporary use or a more permanent use. The US patent documents 4 235 633, 4 542 167, 4 677 140 and 4 684 673 describe such materials. However, none of these materials completely meets the requirement called for at least as regards temporary tooth filling materials.These materials specifically must have an acceptable compres¬ sion strength and at the same time they must not be too strong but rather be brittle to some extent, because they must be comparatively easily removable. Also, the hardening must be done comparatively quickly but on the other side not too quickly.
A brief disclosure of the invention
The object of the present invention is to suggest a new eugenol-free tooth filling material, particularly a mate-
rial designed for temporary use, which meets- the above- mentioned requirements. The present invention is charac¬ terized in that one of the components (A) is pulverulent andmainly is composed of a first powder, which in its turn mainly is composed of zinc oxide, and a second pow¬ der which is a filler, composed of one or several cera¬ mic materials, which are chemically stable in relation to phytic acid, in that the other component (B) is a li¬ quid and is composed of 35-55 % phytic acid and the rest mainly water, in that the material after a careful mixing of the two components with each other is hardened in 2-10 minutes, and in that the compressive strength of the har¬ dened material is 35-55 MPa. When this invention was de¬ veloped, it was found that the grain-size distributionof the zinc oxide, which reacts with the phytic acid, and of the filler material is very important in order to partly obtain the required hardening speed, i.e. between 2 and 10 minutes, and partly obtain a compressive strength of between 35 and 55 MPa. For these reasons the first pow¬ der, i.e. apowderwhich mainly is composedof zinc oxide, will have a grain-size (sieve size) <" 10 um, whereas the pulverulent filler material will be considerably coarser, the main portion of the latter powder having a grain-size (sieve size) of at least 25 um and not more than 125 um. In the following examples the second powder, i.e. the fil¬ ler material, is hydroxyl apatite, i.e. a biocompatible material. However, other calcium phosphate-based materi¬ als are at least potentially feasible, e.g. tricalcium phosphate, Ca-.(PO.) 2 , dicalcium ortophosphate, CaHPO., calcium biphosphate, CafH-PO.),, and fluor apatite, Ca.. (PO,)-.F. Among feasible bioinert materials various me¬ tal oxides, metal nitrides, metal carbides or metal bo- rides can be mentioned, which do not react with phytic acid, e.g. Al-0 3 , TiO-, ZrO_, SiO_, SiN och SiC.
The relationship between the first pulverulent component A and the second liquid component B in the preparation is
also important in order to obtain an optimal strength in combination with an optimal hardening time. Thus, in the compositions of components A and B according to the inven¬ tion the ratio A/B must be < 4 and > 1.5. In case the ratio A/B is 4 or larger the strength will be too high, which means that it is difficult to remove a temporary filling. Also, the preparation will be difficult to work when it is applied, and the hardening reaction will be too fast. In case on the other side the mixture ratio A/B is 1.5 or smaller, the preparation will initially be too loose and not allow a shaping in the required way, when it is applied. Also, the hardening reaction will be too slow and the strength of the hardened material will be too low. In said ratio A/B the amoutn A is expressed in grams and the amount of component V in milliliters.
Said first powder preferably will contain also a small amount of magnesium oxide, MgO, in order to, in a way known per se, moderate the reaction speed of the zinc oxide. If MgO is used, its percentage in relation to the amount of ZnO is to be chosen according to the expression: 0.1 < MgO/ZnO < 1- preferably 0.2 < MgO/ZnO < 0.8. Among other possible additives to the powder mixture lu¬ bricants can be mentioned, which can be admixed in an amount of 1-5 % in order to make it easier to apply the preparation. Such lubricants suitably are one or several polymeric surface-active (surface tension-lowering) sub¬ stances, e.g. polyvinyl alcohol or tensides, e.g. tween 20, tween 30 etc.
In this text the percentages mentioned are always weight percentages.
Additional characterizing features and aspects of the in¬ vention will be explained in the following description of a few embodiments and the obtained results.
Embodiments and results
In a preliminary development work the importance of the grain size of the respective powder in the first compo¬ nent as well as the importance of making this component contain a non-reactive filler having a certain grain sice. More specifically it was found that the reactive powder, i.e. in the first place zinc oxide, was to have a grain size of < 10 um , whereas the main portion of the non-reactive filler powder was to have a grain size of at least 25 u and not more than 125 um , i.e. much coarser than the zinc oxide. In the following table the compositions of the two components (A) and (B) are shown as well as the compressive strength, which was attained after 24 hours.
In the examples 1-9 in the table the ratio A/B was in all the cases 3/1, the amount of component A being ex¬ pressed in grams and the amount of component B being ex¬ pressed in milliliters.
Phytic acid has the following structural formula:
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