Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/884—Preparations for artificial teeth, for filling teeth or for capping teeth comprising natural or synthetic resins
  • A61K6/887—Compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S525/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S525/902—Core-shell

Definitions

• the present invention relates to a material for the production of usable in the dental field plastic moldings, in particular dental prostheses, and their use.
• Dental prostheses can be produced:
• thermos to be used for carrying out the polymerization a distinction is made between hot- and cold-curing systems.
• the boundary between both systems is set at 65 ° C according to ISO 1567: 2000.
• Another possibility for classification is the method of introducing the polymerizable denture mass into the prepared cuvette.
• injection method is particularly advantageous.
• the powder-liquid system is the absolutely dominant and consists of a monomer mixture (predominantly methyl (meth) acrylate) and a powder of a polymer which consists in the majority of cases of a methyl (meth) acrylate homo- or copolymer and above may also contain other fillers and color pigments.
• the polymerization initiation system required in both cases is always included in the components.
• the initiator system In the self-curing systems, the initiator system is usually distributed over the two components (powder and liquid) and is combined during mixing of the components. Once the mixture is made, only a certain handling time remains until the curing has taken place. This can be shortened by increasing the temperature, as known in most chemical reactions.
• the initiator In hot-curing systems, the initiator is usually contained in the polymer component and is distributed in the monomer matrix after mixing. The activation of these heat-curing systems as well as the one-component systems, which usually contain peroxides, takes place predominantly by supplying energy (heating, microwave energy, etc.).
• Thermoplastic injection processes similar to plastic injection molding, process a usually non-crosslinkable thermoplastic material which is injected into the cuvette above the softening point of the plastic. Due to the lack of crosslinking, the mechanical and chemical properties are in many cases insufficient, so that these methods have never prevailed.
• the disadvantage of this method is that it uses a self-activating initiation system that works evenly in the prosthesis mass and that is where the most heat is generated, which is the fastest. In this case, it is not possible to compensate for the volumetric shrinkage occurring during the polymerization, so that a rework is often necessary when fitting the prosthesis to the patient situation.
• the advantage of this method is the shorter process time.
• thermosetting denture materials In the processing of thermosetting denture materials, the polymerization is triggered by increasing the temperature.
• the advantage in the processing of these materials is the high monomer conversion and thus a low residual monomer content and a high chemical resistance of the prosthesis to see, however, the process time is significantly longer and the fit accuracy often worse.
• the most advanced process is the Ivocap process of Ivoclar Vivadent AG (also a hot-curing process), which can almost completely compensate for the ever-present chemical polymerization shrinkage. This is ensured by a directed supply of heat during the polymerization and a high injection pressure of still unpolymerized material. Only the thermal shrinkage, which occurs when cooled from polymerized moldings to room temperature, can not be compensated.
• DE 940 493 discloses a composition of two (meth) acrylate-based bead polymers. The object of this composition is to advantageously modify the batching and processing properties. This goal is achieved by bringing the dough as quickly as possible into a plastic, kneadable state, so that it can be introduced into a cuvette without sticking.
• DE 24 08 640 proposes a solution to the shrinkage problem of casting plastics based on (meth) acrylate.
• the occurring considerable polymerization shrinkage of the monomers should be reduced by reducing the proportion of the monomer phase in the mixture. This is achieved by adding to the monomer solids partially dissolved in the monomer.
• a well-balanced particle size distribution also reduces the space between the individual fillers or polymer beads and thus enables optimized flow properties with the lowest possible monomer content.
• the initiators or co-initiators are free in the system. They are therefore extremely reactive and not suitable for thermally controlled polymerization.
• the published patent application DE 199 41 829 A1 discloses a paste-paste system consisting of two components, which is distinguished by stable mixtures which can not be further changed in their theological properties.
• the polymers or fillers do not swell in the monomer phase.
• the disadvantage of such mixtures is that the composite between filler and matrix is missing and the storage stability of the mixture with initiator is insufficient.
• an inorganic microfiller for dental composites is known.
• the material is preferably used for filling and dental masses. Also denture plastics are mentioned on the edge.
• US 5,154,762 describes a medical or dental cement consisting of two components. These two components each contain a component of the redox system, each of which can also be microencapsulated. This should increase the storage stability of the two cement components. At least one of the two microencapsules is advantageously water-soluble.
• the object of the present invention is now to provide a system which has the advantages of cold polymerization (low polymerization temperatures, low thermal shrinkage, short process times) with the hitherto outstanding properties of the injection process (good tooth adhesion, virtually complete compensation of the polymerization shrinkage, high surface quality and good clinical stability).
• Suitable materials for component A are virtually all monomers which are suitable for dental technology, in particular for the production of prostheses. Particularly preferred is the use of (meth) acrylates, very particularly preferred is the use of methyl methacrylate.
• Component B preferably contains an initiator system, which preferably consists of several components. These can be multiple initiators or multiple activators. Likewise, mixtures of initiators and activators are possible. In a particularly preferred embodiment, the initiator systems are in the form of a combination of activator and initiator in spatially separate form. Particularly preferred here is an initiator system containing at least one activator and at least one initiator.
• the o.g. Spatial separation of the individual components of the initiator system understood that the separation of these components by e.g. whose encapsulation takes place in polymers and thus can not initiate any polymerization start. It is also possible that individual components of the initiator system may also be contained in component A.
• the initiator system comprises at least one initiator which initiates the polymerization reaction by radical formation.
• an activator can be used which accelerates this radical formation and thus the start of the polymerization reaction. If a redox system is used, even more can be used Components are used.
• at least one of the components of the initiator system required for the polymerization is phlegmatized.
• the activator or the initiator can be phlegmatized.
• Phlegmatization in the sense of the invention is understood to mean the reduction of the reactivity. That is, the initiator system allows only a delay in the start of polymerization. This ensures that the components A and B have a longer shelf life and during processing sufficient handling time can be guaranteed and no premature polymerization takes place.
• the phlegmatization is preferably achieved by encapsulating the initiator system components, preferably in a bead polymer.
• a physical encapsulation of the reactive components is accordingly desired.
• This can be achieved, for example, by a monomer-soluble, heat-permeable protective sheath or copolymerization into a microbead.
• Possible methods for microencapsulation are the in-situ polyreaction, coacervation, interfacial, double emulsion, phase separation, etc.
• the components can react directly after release by the addition of heat and thus ensure high monomer conversions.
• Preferred materials according to the invention for the production of plastic moldings which can be used in the dental sector, in particular dental prostheses, consist of a polymerisable component (A), which usually consists of a liquid mixture of polymerizable dental monomers and suitable solid fillers and least one initiator in phlegmatized form (B) for the polymerization of the dental monomers. It is particularly preferred that the initiator or the components of the initiator system be present or provided in phlegmatized form in the filler.
• A polymerisable component
• B phlegmatized form
• the phlegmatization of the initiator system takes place in such a way that the components of the initiator system are encapsulated in a bead polymer in such a way that swelling of the beads can take place only after mixing with the liquid monomer mixture. The swelling also results in a delayed release of the initiator components.
• initiator systems For initiating the polymerization reaction, a large number of initiator systems are known from the prior art, which can also be used according to the invention, ie, phlegmatized. However, preference is given to using initiators for free-radical polymerization. As initiators for the radical polymerization, the known initiators for cold and hot curing are suitable, with a suitably equipped device, the light curing is possible.
• Suitable initiators are described, for example, in the Encyclopedia of Polymer Science and Engineering, Vol. 13, Wiley-Intersci, Pub. New York, etc., 1988, p. 754 et seq.
• Preferred initiators are peroxides, such as dibenzoyl peroxide, dilauroyl peroxide, tert-butyl peroctoate, tert-butyl perbenzoate, or di- (tert-butyl) peroxide or azo compounds, such as azobis (isobutyronitrile) (AIBN) or azo bis (4 -cyanvaleriankla).
• perketals and benzpinacols are also suitable for hot curing.
• redox systems can furthermore be used, in particular combinations of dibenzoyl peroxide, dilauroyl peroxide, or camphorquinone with amines such as N, N-dimethyl-t-toluidine, N, N-dihydroxyethyl-p-toluidine, diethyl p-dimethylaminobenzoate or other structurally related tertiary amines.
• redox systems which contain, in addition to a peroxide or ascorbic acid or derivatives thereof, a barbiturate or a sulfinic acid as a reducing agent.
• Suitable photoinitiators for the UV or visible range are described by JP Fouierier, JF Rabek (ed.), Radiation Curing in Polymer Science and Technology, Vol. IL, Elsevier Applied Science, London and New York 1993, pages 155 to 237, described.
• Preferred photoinitiators are benzoin ethers, dialkylbenzilketals, dialkoxyacetophenones, acylphosphine oxides, bisacylphosphine oxides, ⁇ -diketones, such as 10-phenanthrenequinone, diacetyl, furil, anisil, 4,4'-dichlorobenzil, 4,4'-dialkoxybenzil and camphorquinone.
• the polymerization is started at low temperature. Although the temperature during polymerization increases (exothermicity of the reaction), the temperatures are significantly lower than in the hot polymerization. As a result, two other important process and product parameters are positively influenced at the same time. On the one hand, the thermally induced shrinkage of the prosthesis on cooling to room temperature and the fit of the dental prosthesis is improved and, on the other hand, the process times are reduced, since on the one hand the temperature increase to the required level for hot polymers is eliminated, and on the other hand the cooling process by the lower temperature difference between the highest point during the polymerization and the space or Entformungstemperatur is shorter.
• Another great advantage of the invention is that the known from the prior art and the users (dental laboratories) existing technology can be used and the purchase of new equipment is not required. Very particular preference is given to the use of the material according to the invention in the Ivocap process.
• the shrinkage compensation is easily possible during the polymerization and the shrinkage caused by the polymerization is compensated by a re-pressing unpolymerized prosthesis mass into the cuvette. Since high pressures are used in this process, a high material quality (high homogeneity, no bubbles in the denture material), smooth surface and thus a good clinical resistance (reduced plaque deposition and tendency to discoloration) achieved.
• the release of the encapsulated initiator component can be accelerated.
• This encapsulation has the advantage that when mixing the liquid component with the powder component a sufficiently long time for handling the polymerizable system is available and that after introduction of the polymerizable material in the cuvette by targeted temperature increase (temporally and locally controlled) the Release of the encapsulated initiator component can be accelerated and thus the process time of the size of the plastic molding can be adjusted.
• a reservoir with unpolymerized prosthesis material outside the cuvette is not heated, so that material can be pressed into the cuvette from this reservoir and thus the polymerization shrinkage of the plastic in the cuvette can be compensated.
• the heating of the material in the cuvette preferably takes place in such a way that the temperature increase takes place in the form of a "temperature front" which starts at the cuvette opposite the reservoir with the unpolymerized material and thus starts the polymerization at the "remote” location within the cuvette.
• the exothermicity of the polymerization reaction further accelerates the release of the initiator and extends the heating to the adjacent regions within the cuvette until finally the initiator is completely released and the polymerization is complete.
• the polymerization can thus be controlled by targeted introduction of heat.
• the respective temperatures are in the range of 20 ° C to 90 ° C, preferably 30 ° C to 50 ° C. That is, via the controlled supply of heat, the polymerization is started and controlled.
• further energy is supplied in the further course of production and processing. As a result, a temperature gradient is generated, by the setting reactions can be controlled.
• the temperature gradient in the processing of the inventive materials is based on an initial temperature of 2 ° C to 35 ° C, preferably from 12 ° C to 28 ° C. In stages, the temperature can be increased afterwards. Here are the temperatures of the individual stages at temperatures of 20 ° C to 90 ° C, preferably from 35 ° C to 45 ° C. With the materials according to the invention, it is possible to compensate for the resulting polymerization shrinkage by re-pressed material. The container used in the injection process retains its original temperature and delivers the re-pressed material.
• the materials according to the invention are preferably used in the dental sector; the use for dental prostheses is particularly advantageous.
• the material according to the invention can be used particularly advantageously in combination with the initially described injection method.
• the polymer powder is added in the predetermined mixing ratio to the monomer and thoroughly mixed.
• the pigments are completely distributed in the system.
• the resulting mixture is poured into a front-sealed disposable sleeve.
• the consistency of the unpolymerized masses should ideally be fluid after the mixing of the two components, so that entrained air bubbles can rise and, if possible, there are no air bubbles in the capsule reservoir.
• the material continues to thicken, so that an injectable dough forms with increasing "maturity" of the mixture Injectable means that the consistency of the dough has increased so much that segregation can no longer take place during injection and as much as possible during inflow This consistency is reached after about 5 to 10 minutes from the start of mixing.
• Cooling takes place either directly in the injector via, for example, air cooling, or else the cuvette is removed from the injector and cooled at room temperature in the air or in cold running water. After that she will be put away as usual. It is important that the temperature in the cuvette has fallen so far that the dimensional stability is given under mechanical stress.
• the polymer is a PMMA bead polymer. 7.5% pigments, modifiers, stabilizers, carrier polymers for pigments, etc.
• the initiator polymer is a bead polymer and consists of a copolymer of MMA (85%) and ethylene glycol dimethacrylate (15%).
• thermosetting systems examples include thermosetting systems
• the initiator system for the hot curing consists of the thermal initiator AIBN (N, N-azobisisobutyronitrile), which for the purpose of phlegmatization in
• the initiator copolymer (bead polymer) consists of urethane dimethacrylate (70%), MMA (25%) and ethylene glycol dimethacrylate (5%).
• Production method for prostheses Formulations 1 and 2 can be processed into prosthesis bodies which meet the standard ISO1567: 2000 for cold-curing polymers as well as for hot-curing polymers.
• Formulations 1 and 2 can be used as conventional cold-curing polymers with greatly extended processing time in the casting and the stuffing technique. Furthermore, it can be used as a repair material.
• Formulation 3 can be used in a hot polymerization process, in the so-called stuffing method.

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• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Plastic & Reconstructive Surgery (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Preparations (AREA)
• Graft Or Block Polymers (AREA)

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Citations (12)

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• 2006
  • 2006-03-04 DE DE102006010075A patent/DE102006010075B4/de not_active Expired - Fee Related
• 2007
  • 2007-03-02 JP JP2008557726A patent/JP5455378B2/ja not_active Expired - Fee Related
  • 2007-03-02 EP EP16163084.3A patent/EP3090724B1/de active Active
  • 2007-03-02 EP EP16163080.1A patent/EP3090723B1/de active Active
  • 2007-03-02 US US12/224,699 patent/US8067482B2/en active Active
  • 2007-03-02 WO PCT/EP2007/051975 patent/WO2007099158A2/de not_active Ceased
  • 2007-03-02 EP EP07712418.8A patent/EP1991197B1/de active Active

Patent Citations (12)

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