Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-09-21
2003-12-09
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S116000, C523S118000, C524S183000, C524S184000, C524S413000
Reexamination Certificate
active
06660784
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dental catalyst for chemical polymerization used in the field of dental therapy, to a dental adhesive composition using the dental catalyst for chemical polymerization, and to use of the dental curable composition.
2. Description of Prior Arts
A method of curing a polymerizable monomer by using a catalyst for polymerization has been widely employed in the dental field by using, for example, a dental cement, a dental adhesive, a composite resin, a dental self-curing resin, a dental pretreatment material, etc.
These materials require catalysts for polymerization of different kinds depending upon their compositions, objects of use and required properties. The catalysts for polymerization may be divided into those for photo polymerization and those for chemical polymerization. It, however, becomes necessary to use a catalyst for chemical polymerization when the curable composition contains much filler which permits light to pass through little or when the catalyst is used for such applications where it cannot be irradiated with light. Further, the dental adhesive and the pretreatment material, in many cases, require the use of a catalyst for chemical polymerization depending upon the kind of the dental material that is to be adhered. Besides, the catalyst for photo polymerization must be irradiated with light by using a dedicated device. From the standpoint of easy operation, therefore, it is often desired to use the catalyst for chemical polymerization.
In restoring a tooth damaged by, for example, decaying or accident by directly filling the cavity of the tooth with a paste-like dental restorative as represented by a composite resin or a composite polymer followed by curing (direct restoring method), there has been used, as an adhesive (adhesive for directly restoring the teeth), a bonding agent comprising chiefly a polymerizable monomer which contains an acidic group-containing polymerizable monomer. As the bonding agent, there has been developed an excellent material which does not require the pretreatment that was so far needed (Japanese Unexamined Patent Publications (Kokai) Nos. 263604/1997 and 245525/1998). The above bonding agent, however, uses a particular catalyst for photo polymerization, and it has been desired to omit the operation for irradiation with light in order to simplify the adhering operation. Besides, when the above bonding agent is used in combination with a dental restorative of the chemical polymerization type, the unreacted acidic group-containing polymerizable monomer in the bonding agent reacts with an amine component in the organic peroxide/tertiary amine catalyst that is usually used as a catalytic component for chemical polymerization of the dental restorative. As a result, a sufficient degree of adhering strength is not obtained and, hence, the dental restoratives to be used in combination are limited to those of the photo-curable type only, which is a problem.
Further, according to a restoring method (indirect restoring method) by which a dental restorative such as an inlay or a crown prepared in advance outside the oral cavity by using a metal or a ceramic material, is adhered to a tooth, there is used, as an adhesive, a dental adhesive cement such as an adhesive resin cement or a resin-modified glass ionomer cement comprising, chiefly, a polymerizable monomer that contains an acidic group-containing polymerizable monomer and an organic or inorganic filler. These cements, however, often contain fillers in large amounts or are used in combination with metal materials that do not permit light to pass through. It therefore becomes necessary to use a catalyst for chemical polymerization that is capable of executing the polymerization in a dark place at ambient temperature.
A variety of catalysts for chemical polymerization have heretofore been proposed. Examples of the catalyst for chemical polymerization include those of {circle around (1)} a system using a trialkylboran or a partial oxide thereof (Japanese Unexamined Patent Publication (Kokai) No. 108102/1982), {circle around (2)} a redox-type cold self-polymerization initiator such as a system of a combination of an organic peroxide and a cobalt salt or a manganese salt or a system of a combination of an organic peroxide and a tertiary amine (Japanese Unexamined Patent Publication (Kokai) No. 92884/1976), and a system of a combination of hydrogen peroxide and an Fe2+ compound, {circle around (3)} a system of a barbituric acid, a Cu2+ compound and a Cl−compound (Japanese Unexamined Patent Publication (Kokai) No. 295013/1993), and {circle around (4)} a system of a combination of an aryl borate compound and an acidic compound (Japanese Unexamined Patent Publication (Kokai) No. 309811/1997) and a system of a combination of an aryl borate compound, an acidic compound and a transition metal compound (Japanese Unexamined Patent Publication (Kokai) No. 227325/1997). Among them, some catalysts have been put into a practical use.
Japanese Unexamined Patent Publication (Kokai) No. 169535/2000 discloses a self-curing resin composition that cures at ambient temperature obtained by blending a composition of a combination of (A) a polymerizable unsaturated compound, (B) a radical-generating catalyst, and a polymerization initiator of an organoboron compound represented by the following general formula (I),
with an acidic compound or with (A) the acidic polymerizable unsaturated compound. There has been described that this resin composition is effective in the FRP hand-lay-up molding, or in the FRP lining work in the fields of construction and civil engineering.
The system {circle around (1)} which uses the trialkylboran or the partial oxide thereof is an excellent catalyst for chemical polymerization which is very active but is chemically very unstable. Therefore, this catalyst must be packaged separately from other components, must be picked up in suitable amounts just before it is used and must be mixed with other monomer components, requiring cumbersome operation, which is a drawback.
The catalyst {circle around (2)} for chemical polymerization of a combination of the organic peroxide and the tertiary amine and the catalyst {circle around (3)} for chemical polymerization of the barbituric acid system, are most generally used in the field of dental materials from the standpoint of low beneficial/harmful action to the living bodies and easy availability involving, however, problems as pointed out below.
That is, the catalyst for chemical polymerization of a combination of the organic peroxide and the tertiary amine, involves such problems as tinting the cured product due to oxidation of the amine compound and discoloration, and impairing the polymerization due to oxygen and acidic components (the acidic component here produces a quaternary salt which does not exhibit reducing ability upon reacting with the tertiary amine). The problem of tinting or discoloration causes the color tone to become different from that of a natural tooth when the catalyst is used for a dental restorative as represented by a composite resin, and deteriorates the aesthetic value. The problem of impairing the polymerization means that the catalyst cannot be used for the dental adhesive that uses the acidic group-containing polymerizable monomer as an essential component. The catalyst for chemical polymerization of the barbituric acid type has such problems as difficulty in controlling the curing time and poor preservation stability.
The catalyst {circle around (4)} for chemical polymerization using the aryl borate is easy to handle, does not cause the cured product to be tinted or discolored, and exhibits excellent preservation stability without, however, exhibiting sufficient activity for polymerization. Therefore, further improved activity has been desired.
SUMMARY OF THE INVENTION
As described above, no dental catalyst for chemical polymerization has yet been known, which is chemically stable, easy to handle, highly active, les
Ibaragi Kazuya
Kazama Hideki
Oguri Makoto
Sherman & Shalloway
Tokuyama Corporation
Yoon Tae H.
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