Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
2002-08-02
2004-08-03
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
C424S057000, C433S215000, C433S216000, C433S228100, C106S035000
Reexamination Certificate
active
06770265
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tooth surface treatment material and a tooth surface treatment method for treating a dental cavity during undergoing restorative for a deficient part of a tooth structure in the dental therapy. More particularly, the present invention relates to a tooth surface treatment material and a tooth surface treatment method for more enhancing and stabilizing an adhesive force between a glass ionomer cement and a tooth structure within a dental cavity.
2. Description of the Related Art
In the present dental therapy is usually employed a restorative in which a dental caries part is cut to form a cavity by using a diamond point, etc., and the thus formed cavity is filled with a filling material such as a glass ionomer cement and a composite resin. If such filling material does not firmly adhere to a tooth structure within a dental cavity, the filling material comes off so that a patient must take again the therapy. Alternatively, even if the filling material does not come off, when a gap is present, there is a high possibility to generate a crisis of secondary dental caries. Accordingly, relative merits of the adhesion between the filling material and the tooth structure within the dental cavity is one of the important factors in clinching the restorative.
However, when the tooth is cut to form a cavity, its cutting wastes, saliva, etc. are rubbed on the tooth surface to form a smear layer having a thickness of 1~5 &mgr;m. This smear layer cannot be eliminated by water, hydrogen peroxide, etc. When the smear layer is present between various filling materials and the tooth structure within the dental cavity, the adhesion becomes very instable, possibly resulting in decrease in and scattering of the adhesive force.
As a method for eliminating the smear layer, there has hitherto been used an acid-etching method using a phosphoric acid solution of 30~60% by weight. This method that a tooth surface within a dental cavity is treated with a phosphoric acid solution for a predetermined period of time to dissolve a smear layer therein and then rinsed with water to eliminate the smear layer. In the case where the tooth structure cut is of an inorganic component-rich enamel, after eliminating the smear layer by phosphoric acid-etching, a glass ionomer cement is filled, an improving effect of the adhesive force is observed. However, since the glass ionomer cement exhibits adhesive properties to the tooth structure by bonding between the inorganic component in the tooth structure and a carboxyl group of the glass ionomer cement, in an inorganic component-poor dentin, the healthy dentin is also demineralized by the phosphoric acid-etching. In this case, when the inorganic component is lost, the adhesive force was likely lowered.
Thus, there was required a tooth surface treatment material that can eliminate the smear layer so that the glass ionomer cement can obtain a strong adhesive force to the tooth structure within the dental cavity and is able to feed the inorganic component to the tooth structure.
In order to meet such require, West German Laid-Open Patent OLS No. 2,452,969 discloses a method in which a first solution is prepared as a solution of a water-soluble calcium salt of 0.005~5% having a pH of less than 5, a second solution is prepared as a solution of a water-soluble phosphate of 0.005~5% having a pH of 2.5~4, and the first solution and the second solution are mixed to prepare a solution having a pH of from 2 to 5, which is then applied onto a tooth surface. According to this method, since the solution prepared by mixing the two solutions is low in acidity being pH 2~5, it takes a long period of time to eliminate the smear layer. Also, since the mixed solution is applied onto the tooth surface after mixing the calcium component in the first solution and the phosphoric acid component in the second solution, prior to the contact with the tooth surface a calcium ion and a phosphoric acid ion are already reacted with each other to form a crystal. Accordingly, the penetration properties of the calcium ion and the phosphoric acid ion into the interior of the tooth structure are poor, and the reactant only accumulates on the tooth surface, so that an improvement in the adhesive force between the glass ionomer cement and the tooth structure within the dental cavity cannot be expected.
Further, JP-B-86367/1994 titled “TREATING AGENT OF TOOTH SURFACE” discloses a treating agent of tooth surface for treating an enamel surface and/or a dentin surface, which consists of 5~50% by weight of an organic carboxylic acid or an anhydride thereof, 5~50% by weight of calcium chloride, and water. According to this treating agent of tooth surface, the smear layer can be eliminated, and the calcium ion can be made to penetrate into the tooth structure. However, the calcium ion is only dissolved in the penetration solution. When a time elapses, the calcium ion is taken into a body, so that an effect for keeping the adhesion between the glass ionomer cement and the tooth structure within the dental cavity over a long period of time cannot be expected.
SUMMARY OF THE INVENTION
The present invention is aimed to overcome the above-described defects of the related art and to provide a tooth surface treatment material and a tooth surface treatment method capable of eliminating a smear layer, delivering an inorganic component of a tooth structure within a dental cavity to the tooth structure, and making a glass ionomer cement firmly adhere particularly to a dentin.
The present inventor has made extensive and intensive investigations in order to achieve the above-described aim. As a result, it has been found that with respect to a tooth surface treatment material comprising an aqueous solution containing 2~30% by weight of a water-soluble calcium salt and an acid which does not react with the water-soluble calcium salt so as not to form a compound in an amount of
½ or less of the weight of the water-soluble calcium salt and having a pH of
2 or less, and another aqueous solution containing from 2 to 30% by weight of a water-soluble phosphate other than a calcium salt, and a tooth surface treatment material comprising an aqueous solution containing 2~30% by weight of a water-soluble calcium salt and another aqueous solution containing 2~30% by weight of a water-soluble phosphate other than a calcium salt and an acid which does not react with the water-soluble phosphate so as not to form a compound in an amount of
½ or less of the weight of the water-soluble phosphate and having a pH of
2 or less, when the acid-containing aqueous solution is first applied onto a tooth surface, not only a smear layer can be dissolved by the acid, but also the water-soluble calcium salt or the water-soluble phosphate other than a calcium salt contained in the acid-containing aqueous solution can be delivered to a tooth structure within a dental cavity; when the other aqueous solution not containing an acid is subsequently applied onto the tooth structure, the water-soluble phosphate other than a calcium salt or the water-soluble calcium salt contained in the other aqueous solution is delivered to the tooth structure and reacts with the water-soluble calcium salt or the water-soluble phosphate other than a calcium salt as previously delivered to the tooth structure to form a compound, so that when the tooth surface is then rinsed with water, though the smear layer is eliminated, the inorganic component delivered to the tooth structure remains on the tooth structure, thereby enabling to improve and stabilize an adhesive force between a glass ionomer cement and the tooth structure, leading to accomplishment of the present invention.
Specifically, the present invention is to provide a tooth surface treatment material comprising an aqueous solution containing 2~30% by weight of a water-soluble calcium salt and an acid which does not react with the water-soluble calcium salt so as not to form a compound in an amount of
½ or less of th
Ishihara Yoko
Yoshii Eiichi
GC Corporation
Rose Shep K.
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