Compositions: coating or plastic – Coating or plastic compositions – Dental
Reexamination Certificate
2001-03-26
2003-03-25
Koslow, C. Melissa (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Dental
C424S049000, C523S115000, C523S113000
Reexamination Certificate
active
06537360
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a tooth coating composition to be applied over teeth for attaining improvements in dental health and/or appearance.
BACKGROUND OF THE INVENTION
As people age, their teeth tend to turn to a natural yellow or dark color. Also, yellowing or darkening of teeth is sometimes caused by dental treatments. It is substantially impossible to remedy such undesirable cosmetic phenomena merely by brushing one's teeth with tooth powder or toothpaste. Currently, one general approach is to apply a coating film over the teeth to attempt to remedy these undesirable phenomena.
The tooth coating compositions for applying such tooth coating films that have been previously known include those comprising cyanoacrylate or derivatives thereof as main components, which were developed by the present inventors and disclosed in Japanese Patent Publication No. Sho 41-11000 and Japanese Patent Publication No. Sho 45-27225; and those comprising shellac resin as main components. Recently, there have been developed several examples of coating agents for teeth using dental cements such as glass ionomer cement, carboxylate cement and the like.
The tooth coating compositions comprising cyanoacrylate as their main component have, however, a defect in that after the coating has been applied and later becomes damaged so as to be unsightly, it is very difficult to remove from the teeth because the coating film formed using a tooth coating agent has extremely strong adhesion to the teeth and there is no suitable removing agent therefor.
On the other hand, the tooth coating agents using shellac resin as their main component are likely to peel off from teeth when the user is having a meal. Such a coating agent has further defects such as unnatural whitening to a plaster-like coloroccurring several hours after application, and unevenness of color generated in each application due to poor dispersing stability of pigments.
Those compositions based on dental cements also have a problem in removal because they also have strong adhesion to the teeth, and removal thereof requires special skills. Thus, the tooth coating agents using the dental cements cannot be easily used by ordinary consumers due to the extremely difficult removing operation.
SUMMARY OF THE INVENTION
Consequently, an object of the present invention is to provide a tooth coating composition kit that provides a color approximate to the color of natural teeth, causes little irritation to mouth, and attains both high durability and easy removability after use so that it can be easily utilized by ordinary consumers.
As a result of intensive research carried out by the present inventors in order to solve the above-mentioned problems and thus achieving the above-mentioned object, the present inventors have found that a tooth coating composition which provides a color approximate to the color of natural teeth, causes little irritation to mouth, and attains high durability and easy removability after use so that it can be easily handled by ordinary consumers, are obtained according to the present invention by using polycarboxylic acids, reactive metallic oxides, a coating film-softening agent and a reaction retarder.
The durability and natural tooth color of the tooth coating composition according to the present invention can, however, be further improved to even better inhibit any unnatural white or turbid appearance after several hours have elapsed from application of a coating film over teeth. In order to accomplish this improvement, the present inventors further developed an over-coating composition to be applied over the aforementioned film formed of the teeth coating composition applied to teeth. The combination use of the tooth coating composition and the over-coating composition therefor can realize a tooth coating film without occurrence of whitening or turbidity.
Specifically, the tooth coating composition kit according to the present invention comprises a component A comprising at least a reactive metallic oxide; and a component B comprising at least water; these components are mixed with each other when using the tooth coating composition. The tooth coating composition is characterized in that a polycarboxylic acid, a reaction retarder and a coating film-softening agent are contained in at least one of the component A and the component B.
The over-coating composition for the tooth coating composition according to the present invention is characterized in that it comprises as its main component one or more coating film-forming substances selected from the group consisting of shellac resin, polyvinyl acetate resin and alkyl acrylate copolymers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The details of the present invention will be described hereinafter with reference to but not limited to the following preferred embodiments.
Polycarboxylic acids have carboxyl groups within molecules and react with reactive metallic oxides under acidic conditions and in the presence of water, whereby tenacious coating films are formed. The durability of the coating film becomes lower when the average molecular weight of the polycarboxylic acid is less than 4000, whereas the applying properties would be deteriorated due to an over-great viscosity when the average molecular weight of the polycarboxylic acid exceeds 10000. As a consequence, the average molecular weight of the polycarboxylic acids is preferably within a range from 4000 to 9000, and preferably about 8000.
The polycarboxylic acids used in the tooth coating composition according to the present invention are one or more compounds selected from the group consisting of polymers and copolymers of acrylic acid, methacrylic acid, maleic acid and itaconic acid. Concrete examples thereof include polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic copolymers, acrylic acid-itaconic acid copolymers, acrylic acid-maleic acid copolymers, polymaleic acids, polyitaconic acids, etc.
The polycarboxylic acid reacts with the reactive metallic oxide in the presence of water to form a tenacious coating film. For practical use, the reactive metallic oxides in the tooth coating composition according to the present invention is one or more metallic oxides selected from the group consisting of zinc oxide, calcium oxide and aluminum oxide. Zinc oxide has rich reactivity and therefore can be used by itself. On the other hand, the reactivity of both calcium oxide and aluminum oxide is comparatively poor, and therefore using a mixture thereof especially with zinc oxide is recommendable.
In addition to the metallic acids stated above, magnesium oxide and silicon oxide have a similar effect. However, they need to be used in combination with at least one other metallic oxide, preferably zinc oxide, since the practical effects thereof are extremely small when they are singly used. In particular, magnesium oxide and/or silica oxide can be used to reduce the quantity of zinc oxide.
The content of the metallic oxides with respect to the entire composition (i.e., the total amount of the component A and the component B) is preferably within a range from 0.2% to 35%. If the content is less than 0.2%, the coating film is unduly week and easily peeled. On the other hand, if the content is greater than 35%, the coating film becomes hardened too quickly, thus causing difficulty in the applying operation. The content of the metallic oxides with respect to the entire composition is more preferably within a range of from 2% to 15%.
The content of the polycarboxylic acid with respect to the total amount of the component A and the component B is preferably within a range from 5% to 40%, especially from 10% to 20%. If the content is less than 5%, the coating film has the luster without the gloss and is unduly week and easily peeled. On the other hand, if the content is greater than 40%, the coating film does not dry well and it tends to dissolve in the mouth and becomes easily removed.
In the tooth coating composition according to the present invention, the reactive metallic oxides si
Aida Harumi
Inagaki Kenji
Matsumoto Takashi
Miyama Torao
Tanaka Kichizo
Browdy and Neimark , P.L.L.C.
Hanix Co., Ltd.
Koslow C. Melissa
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