Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1979-07-31
1983-02-08
Lieberman, Paul
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
523116, 524779, 524783, 433228, C08F 250, C08K 316
Patent
active
043728367
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Tooth filler material on the basis of unsaturated polyesters, e.g., diacrylate or dimethacrylate ester compounds which can be hardened quickly in situ by light in the presence of certain polymerization initiators, have been known for a long time. Thus, in British Pat. No. 569,974, photopolymerizable dental masses for fillings of teeth have been described, which consist of a mixture of polyacrylates and acrylate ester monomers and contain benzoin as photoinitiator. These masses are then hardened by irradiation by means of a UV light source, after application in the mouth. Also German OS 21 26 419 or the corresponding U.S. Pat. No. 3,709,866 as well as the German OS 21 35 645 describe such dental masses polymerizable by UV light, which additionally contain polymerization catalysts in order to achieve a quick and complete hardening. The light sensitivity of the polymerizable masses on the basis of acrylic acid esters can be further increased by certain activators, especially aliphatic or aromatic or mixed aliphatic-aromatic phosphites, as described in the German OS 26 46 416.
In order to achieve a safe and especially a complete polymerization and hardening of the fillings of the teeth, it is necessary for the material that is to be hardened in situ by radiation to have a good permeability for short wave light so that the rays can penetrate not only the surface area but also deep into the mass down to its rear surface, in order to initiate there as well the polymerization at the same intensity as is the case on the surface of the fillings facing the radiation source.
This good light permeability of the tooth filler masses, however, has some cosmetic disadvantages when they are used in the frontal area of the teeth for approximal cavities that no longer possess the palatinal wall, since in such a case these translucent fillers have a dark appearance because of the dark background of the oral cavity. A similar problem results in case of fillings of a small thickness lacking a tooth-colored background, e.g., with a translucently visible, protective base. Obviously, a difficult problem results in such a case of light hardenable tooth filler masses. That is, if for cosmetic reasons one uses a white pigmented material, e.g., a mass filled with lithopone, titanium dioxide or zinc oxide for fillings in such locations, only a thin surface layer of the tooth filler is hardened upon irradiation with light, because these pigments absorb not only the visible, but also more or less strongly the radiation in the UVA and the near-UVA range of the spectrum (about 320-500 nm). Consequently, such a filling must be built up by layers and hardening by irradiation must be carried out after the application of each thin layer. As a result, however, the dentist is under a heavy strain and the treatment is so greatly delayed that the advantages of the photohardenable tooth filler material are lost in the case of such applications in the frontal area of the teeth. Therefore, they have heretofore not established themselves for such lateral tooth fillings in the frontal area of the set of teeth.
Now, it was surprisingly discovered that a sufficiently penetrating hardening can be achieved if finely divided calcium fluoride is used as a pigmenting filler for these photohardenable dental masses. According to this invention, this pigment is preferably used in the case of such tooth filler material for the frontal area in a quantity of 1-20% by weight, most preferably 2-15% by weight, relative to the filler mixture. Calcium fluoride is physiologically harmless. The particle size is preferably below 60.mu.; calcium fluoride of <10.mu. being especially suitable. If desired, finely divided, so-called colloidal silica may also be present as a reinforcing agent in order to avoid settling phenonmena in the filler material, since this pure silicon oxide material, as is well known, is permeable to UV light, which is also more or less true for the visible region when it is sufficiently finely enough and uniformly dispersed in the resin
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Hubner Heinz-Joachim
Jochum Peter
Purrmann Robert
Schmitt Werner
Espe Fabrik Parmazeutischer Praparate GmbH
Koeckert A. H.
Lieberman Paul
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