Coating processes – Medical or dental purpose product; parts; subcombinations;... – Particulate or unit-dosage-article base
Patent
1981-09-11
1982-09-28
Silverberg, Sam
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Particulate or unit-dosage-article base
20415923, 433201, 433202, 430281, 427 541, C08F 246
Patent
active
043518532
DESCRIPTION:
BRIEF SUMMARY
For the production of the different prosthetic dental appliances, such as complete crowns, veneers of metal crowns as well as the visible part of dental bridge constructions, polymerizable masses on the basis of ethylenically unsaturated compounds are used on a large scale in addition to the ceramic materials. Due to their lower price, their easier processing and their lower brittleness, the appliances produced from plastic materials are frequently preferred to ceramic materials, especially since the ceramic appliances have an essentially higher hardness than the natural tooth substance, and thus, upon their use, the respective antagonist tooth is subjected to wear.
As monomer base for the production of the plastic materials and appliances, methylmethacrylate as well as difunctional or polyfunctional acrylic acid esters or methacrylic acid esters are mostly used as ethylenically unsaturated compounds, wherein fillers, dyes, fluorescent substances, and the like are added to the monomers prior to the polymerization for reduction of the shrinkage during the polymerization and for the increase of the mechanical strength as well as for the colour matching. to the natural teeth. Inter alia, previously pigmented beads of polymethacrylate or other pulverised organic polymerizates as well as also inorganic fillers, especially microfine fillers as e.g. pyrogenic silicic acid are suitable as fillers.
These monomer masses must be available in a wide range of shades for the production of esthetically unobjectionable appliances. Among them, there are also very light colours, e.g. for the masses used for the incisal part of the tooth and therefore, the raw materials must be feasible for the production of completely colourless polymerizates, thereby guaranteeing the colour stability up to more than one decade.
The polymerization and curing of the monomer preparations can be obtained in principle by the addition of conventional radical generating substances as polymerization catalysts. Due to the considerable demands on the colour stability, only the hot polymerization using peroxides, e.g. lauroylperoxide or benzoylperoxide has been proved useful. Due to the limited stability of the ready-prepared mixtures of monomer, fillers and additional ingredients as well as the peroxides, these masses are usually available as two component systems for the dental technician, wherein one of the components is a monomer preparation free of peroxide and the other a peroxide preparation free of monomer. Directly prior to the processing, both components are then mixed.
These two-component systems are, however, uncomfortable in the handling because of the required mixing step wherein incorrect dosage and, especially, an inhomogeneous mixture as well as inclusions of air within the mass lead to defects which jeopardize the success of the working. Moreover, the non-utilized residues of the respectively freshly prepared mixture must be discarded since they cannot be preserved.
Therefore, one-component systems have already been developed, having a photoinitiator system as radical generating substance. The curing of the polymerizable mass is then achieved by irradiation of light. Such preparations, which are stable during dark storage have been proved useful as tooth-filling materials in previous years. The photoinitiators such as benzoinalkylethers or benzilmonoketals, responding to UV-light, especially of a wave-length of 320 to 400 nm show, however, insufficient colour stability, especially in the very light dyeings required in crown materials and bridge materials, and lead, especially in the partly required darker dyeings of the monomer preparations to insufficient hardenings within the interior of the shaped bodies produced therefrom. Furthermore, the irradiation with UV-light requires technically complicated, and thus expensive, lamps which show a relatively poor durability, only.
The DE-OS No. 29 14 537 describes such mixtures for the production of tooth crowns, wherein benzil and benzoinalkylethers are used as photoinitiators. For achiev
REFERENCES:
patent: 3756827 (1973-09-01), Chang
patent: 4024297 (1977-05-01), Gruber
patent: 4071424 (1978-01-01), Dart et al.
patent: 4131729 (1978-12-01), Schmitt
Gasser Oswald
Jochum Peter
Espe Fabrik Parmazeutischer Praparate G.m.b.H.
Silverberg Sam
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