Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-12-11
2001-01-30
Kulkosky, Peter F. (Department: 1615)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06180688
ABSTRACT:
The invention relates to composite materials on the basis of one or more non-acid, non-ionic, hydrophilic crosslinker monomers and one or more non-acid, non-ionic, hydrophilic dilution monomers having a viscosity of <1 Pas, which are suitable in particular as dental materials.
Dental materials which are capable of releasing ions, such as for example fluoride, calcium or hydroxide ions, in the oral cavity are increasingly of interest because of their remineralizing, bioactive and cariostatic action.
Restorative dental materials which display a caries-inhibiting action because they contain sources of fluoride, such as special chlorohexidine-fluoride compounds, are known e.g. from U. Salz, Phillip Journal 14 (1997) 296.
Further examples of ion-releasing dental materials are glass ionomer cements and compomers whose organic matrix is made up at least in part from acid monomers, oligomers or polymers (A. D. Wilson, J. W. McLean, Glasionomer Cement, Quintessence Publishers, Chicago 1988; J. Nicholson, M. Anstice, Trends Polym. Sci. 2 (1994) 272; R. Hickel, L. Kremers, C. Haffner, Quintessenz 47 (1996) 1581).
Glass ionomer cements are water-containing, two-component cements on the basis of polymeric organic acids such as for example poly(acrylic acid) and powdery, solid bases such as calcium-fluoride-aluminium silicate glasses. The curing of the cement takes place through ionic reaction between polymer-bound COOH groups and the calcium or aluminium ions emerging from the filler, so that the components of the glass ionomer cement can be mixed only shortly before use. This is laborious, and moreover the inclusion of air is unavoidable in most cases, which adversely affects the strength of the material. Because of their poor bending strength, glass ionomer cements are not suitable for occlusion-bearing fillings.
The term compomers is taken to mean compositions which are composed of polymerizable acid monomers and ion-releasing glass particles. They are anhydrous single-component systems which cure through radical polymerization of the monomer matrix. Acid-base reaction takes place to a small extent only when water is absorbed into the filling via saliva. The non-cured materials are moisture-sensitive, and uncontrolled contact with water, for example during production or storage, leads to a premature curing which makes the material unusable. Compomers have a greater mechanical strength than glass ionomer cements, but frequently display a smaller ion release.
Both glass ionomer cements and compomers generally display a high ion-release capacity when the matrix of the materials has an adequate hydrophilic character which encourages absorption of water. In the case of glass ionomer cements, the matrix is formed by polyalkene acids, whereas in the case of compomers it is above all carboxylic acid-containing monomers that are used as matrix materials. However, since a high water content or a high water absorption has a disadvantageous effect on the mechanical properties of polymers, it was not previously possible to produce materials having a high ion-release capacity which simultaneously display a high mechanical strength.
EP 0 449 399 B1 discloses as underfilling materials suitable composites on the basis of ion-releasing fillers and a mixture of customary dental monomers, such as e.g. the di-methacrylate of ethoxylated bisphenol-A, a hydrophobic dimethacrylate, with the urethane dimethacrylate comprising 2-hydroxyethyl methacrylate and 2,2,4-trimethyl hexamethylene diisocyanate, which do not contain acid monomers but do display only a small ion release.
The object of the invention is to provide composite materials having a high ion-release capacity and high mechanical strength capacity which are storage-stable in the uncured state even under moist conditions and whose mechanical properties are not substantially impaired after curing by the addition of water.
This object is achieved by composite materials on the basis of polymerizable monomers which are characterized in that the material contains a mixture of
(a) at least one non-acid, non-ionic, hydrophilic crosslinker monomer,
(b) at least one non-acid, non-ionic, hydrophilic dilution monomer having a viscosity of <1 Pas and
(c) at least one ion-releasing filler.
The term crosslinker monomers is taken to mean monomers which contain at least two, preferably 2 to 4 groups capable of polymerization per monomer molecule.
The monomers are hydrophilic, i.e. they are capable of hydrophilic interactions with the filler. Monomers are preferred which contain one or more, preferably 1 to 2 urethane and/or OH groups, preferably OH groups. It was also found that these groups promote ion transport or ion emission.
The term non-acid compounds is taken to mean monomers which carry no strongly acidic groups such as carboxyl, phosphoric acid, phosphonic acid, phosphinic acid or sulphonic acid groups and which preferably also contain no weakly acid groups such as phenolic OH groups or SH groups or CH-acid groups such as &bgr;-diketone or &bgr;-diketoester groups.
Non-ionic monomers within the meaning of this invention are those which contain no ionic groups such as cationic ammonium or sulphonium groups or anionic acid residue groups of the strongly acid groups named above.
Preferred crosslinker monomers are 2,2-bis-4-(3-methacryloxy-2-hydroxypropyl)-phenylpropane) (bis-GMA), i.e. the reaction product of glycidyl methacrylate and bisphenol-A (containing OH groups), and 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12-diaza-hexadecan-1,16-diyl-dimethacrylate (UDMA), i.e. the urethane dimethacrylate comprising 2 moles of 2-hydroxyethyl methacrylate (HEMA) and 1 mole of 2,2,4-trimethyl hexa-methylene diisocyanate (containing urethane groups). Also preferred as crosslinker monomers are reaction products of glycidyl methacrylate with other bisphenols, such as e.g. bisphenol-B (2,2′-bis-(4-hydroxyphenyl)-butane), bisphenol-F (2,2′-methylene diphenyl) or 4,4′-dihydroxydiphenyl), as well as reaction products of 2 mol HEMA or 2-hydroxypropyl(meth)-acrylate preferably with 1 mole of known diisocyanates, such as e.g. hexamethylene diisocyanate, m-xylylene diisocyanate or toluylene diisocyanate.
The term dilution monomers is taken to mean monomers having a viscosity of <1 Pas, preferably <100 mpas, which are suitable for diluting the generally highly viscous cross-linker monomers and thus permit the production of composites with a high filler content. The viscosity data relate to a temperature of 23° C. The viscosity is measured by means of a plate or rotation viscometer in accordance with DIN 53018.
The dilution monomers likewise contain at least two, preferably two to three groups capable of polymerization and at least one, preferably 1 to 2 OH and/or urethane groups, preferably OH groups. They are non-ionic and non-acid compounds.
A particularly preferred dilution monomer is glycerol dimethacrylate (GDMA). Other preferred dilution monomers can be produced by reaction of low-viscosity di- or triepoxides, such as for example ethylene glycol diglycidyl ethers, glycerol triglycidyl ethers or trimethylolpropane triglycidyl ethers with (meth)acrylic acid. Further preferred are also the reaction products of 2 or 3 moles of methacrylic acid with glycerol triglycidyl ether or trimethylolpropane triglycidyl ether. The term “low-viscosity” is taken to mean substances having a viscosity of <200 mPas, preferably <100 mPas (23° C.).
Preferred groups capable of polymerization are, in the case of both crosslinker monomers and dilution monomers, methacryl and/or acryl groups, in particular methacryl groups.
To produce composite materials, crosslinker monomers and dilution monomers are mixed with fillers, initiators for radical polymerization and optionally other auxiliaries. Single-component composite materials, i.e. composite materials which contain all the necessary components, are preferred.
The composite materials according to the invention preferably have the following composition:
(a) 1 to 40 wt.-%, particularly preferably 10 to 30 wt.-% and quit
Fischer Urs Karl
Grabher Kurt
Moszner Norbert
Rheinberger Volker
Rumphorst Andr{acute over (e)}
Ivoclar AG
Kulkosky Peter F.
Nixon & Peabody LLP
LandOfFree
Ion-releasing composite material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ion-releasing composite material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ion-releasing composite material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2510695