Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-05-07
2001-09-18
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C106S035000, C433S214000, C524S403000, C524S442000, C524S494000, C524S506000, C524S731000, C524S862000, C524S863000, C528S032000
Reexamination Certificate
active
06291546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silicone composition for oral mucosa impression, which is used for undergoing oral mucosa impression taking with a good accuracy in the preparation or adjustment of dentures in the dentistry.
2. Description of the Related Art
In the dentistry, it is necessary to precisely reproduce the shape of an oral mucosa at the time of preparation or adjustment of a denture. If the shape of an oral mucosa is not precisely reproduced, the fittness between a denture base and an oral mucosa is lost, the denture likely becomes inferior in stability. As the result, when a patient masticates, not only the patient feels a pain on the oral mucosa, but also the mastication itself may become impossible with the denture coming out from the oral mucosa when the patient opens his or her mouth. For these reasons, there have been made various efforts for obtaining impression of the shape of an oral mucosa with a good accuracy using various impression materials. However, there are still various problems as described below, and the present state is that the impression taking with a good accuracy is not carried out.
In order to obtain the oral mucosa impression with a good accuracy, it is a necessary condition that in the impression taking, an impression material impresses precisely the shape of an oral mucosa without deforming the oral mucosa. For this, in bringing the impression material press-contacted with the oral mucosa, it is necessary to make a pressure to be applied to the mucosa press as low as possible. As the impression materials capable of obtaining the impression without applying an excessive pressure to the oral mucosa, there has since long been known a zinc oxide eugenol-based impression material. However, since this impression material has an irritation to the oral mucosa and gives an extreme pain to a patient at the time of impression taking, it is hardly used at the present time. For these reasons, dental impression materials developed mainly for the impression taking of crowns, bridges, and the like, such as an alginate, a polysulfide polymer, and a silicone, are usually used. However, since these impression materials do not flow unless a relatively high pressure is applied, an excessive pressure is applied to the oral mucosa at the time of impression taking, resulting in an incomplete impression with an inferior accuracy. In addition, the majority of patients who set a denture is a relatively aged person and is low to a vomiting reaction. Thus, in case of an impression material that readily flows spontaneously, there may be a danger that the impression material comes into the innermost part of a throat at the time of press contact.
Accordingly, in order to effect the oral mucosa impression taking with a good accuracy, an impression material is required to have such properties that although it flows by a very low pressure upon which the oral mucosa does not cause deformation, it does not come into the innermost part of a throat. Even materials having such properties can not be put into actual use if they have a large irritation to the mucosa.
SUMMARY OF THE INVENTION
Thus, an object of this invention is to provide an impression material for oral mucosa impression taking, having such properties that it flows by a very low pressure; in case where no pressure is applied, it does not substantially flow; and that it has a very low irritation to an oral mucosa.
In order to attain this object, the present inventors made extensive and intensive investigations. As a result, it has been found that if an organopolysiloxane having at least two aliphatic unsaturated hydrocarbons in one molecule and having a specified viscosity, an organohydrogen polysiloxane having at least three hydrogen atoms directly bonded to a silicon atom in one molecule, a silicone-soluble platinum compound, a linear methylphenyl polysiloxane having a specified viscosity, an inorganic filler, and a surfactant are compounded with each other in a specified ratio, owing to a mutual effect among the organopolysiloxane having a specified viscosity, the linear methylphenyl polysiloxane having a specified viscosity, and the surfactant, a silicone composition for oral mucosa impression that flows by a marked low pressure as compared with impression materials which have hitherto been used in the dentistry, does not substantially flow in a portion to which no pressure is applied, and that does not have an irritation to an oral mucosa, can be obtained, leading to accomplishment of this invention.
That is, the silicone composition for oral mucosa impression according to this invention comprises:
(A) 100 parts by weight of an organopolysiloxane having at least two aliphatic unsaturated hydrocarbons in one molecule and having a viscosity at 25° C. of 500~1,500 cS;
(B) 0.1~20 parts by weight of an organohydrogen polysiloxane having at least three hydrogen atoms directly bonded to a silicon atom in one molecule;
(C) 10~500 ppm, based on the total amount of the components (A) and (B), of a silicone-soluble platinum compound;
(D) 1~20 parts by weight of a linear methylphenyl polysiloxane having a viscosity at 25° C. of 30~10,000 cS;
(E) 10~200 parts by weight of an inorganic filler; and
(F) 0.5~5 parts by weight of one or more than two surfactants selected from nonionic surfactants.
DETAILED DESCRIPTION OF THE INVENTION
(A) As the organopolysiloxane having at least two aliphatic unsaturated hydrocarbons in one molecule and having a viscosity at 25° C. of 500~1,500 cS, the preferred organopolysiloxane are linear and terminated by vinylsilyl groups at the both ends of the molecular chain thereof. This terminal vinyl group may be present in the plural number, and the vinyl group may be included in the chain. This organopolysiloxane is a base material, and for its kneaded impression material to have such properties as it flows by a very low pressure, the viscosity at 25° C. must be from 500 to 1,500 cS. If the viscosity at 25° C. of the organopolysiloxane is lower than 500 cS, the resulting set material is brittle, whereas if it exceeds 1,500 cS, the pressure by which the kneaded impression material flows is too high. Accordingly, the both cases it is not suitable for the oral mucosa impression taking.
(B) The organohydrogen polysiloxane having at least three hydrogen atoms directly bonded to a silicon atom in one molecule functions as a crosslinking agent and is required to have at least three hydrogen atoms directly bonded to a silicon atom in a molecule thereof. If the amount of the organohydrogen polysiloxane is less than 0.1 part by weight based on 100 parts by weight of the component (A), not only the hardness of a set material is lowered, but the setting rate is slow, whereas if it exceeds 20 parts by weight, when a kneaded impression material comes into contact with the oral mucosa, the setting extremely proceeds so that the impression material is set while it flows on the mucosa. Accordingly, in the both cases it is not suitable for the oral mucosa impression taking.
(C) Examples of the silicone-soluble platinum compound include known addition reaction catalysts such as chloroplatinate, alcohol-modified chloroplatinate, and a complex of chloroplatinate with an olefin. In particular, a chloroplatinate-vinylsiloxane complex is preferably used. A suitable amount of the component (C) is in the range of 10~500 ppm based on the total amount of the components (A) and (B). If the amount of the component (C) is less than 10 ppm, the setting rate is slow, and in case where a trace amount of a substance which hinders the catalytic ability of the platinum compound is present, the setting becomes slow. On the other hand, if it exceeds 500 ppm, not only the setting rate is too fast, but the production cost is high, resulting in an economic disadvantages. Incidentally, it is preferred to use the silicone-soluble platinum compound such as chloroplatinate after being dissolved in an alcohol-, ketone-, ether- or hydrocarbon-based solvent, a polysiloxane oil, etc.
(D)
Kamohara Hiroshi
Takeo Makiko
GC Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Szekely Peter
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