Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-09-20
2004-09-14
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...
C522S008000, C522S047000, C522S064000, C522S112000, C522S171000, C522S173000, C522S182000, C522S185000, C522S908000, C523S109000, C523S116000, C523S117000
Reexamination Certificate
active
06790877
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to bonding compositions suitable for dental use. More precisely, the invention relates to bonding compositions suitable for dental use, which exhibit good adhesiveness between a tooth and restorative dental materials in dental treatment, and which are for preventing the growth of cariogenic bacteria in the bonded area.
2. Description of the Related Art
In dental treatment, where partial defects in teeth are restored through prosthesis with restorative dental materials such as, for example, composite resins, monomers, metal alloys and ceramics for dental restoration, dental bonding compositions are often used. However, when such a restorative dental material is directly bonded to the surface of a tooth, it does not exhibit satisfactory bonding strength since it is not adhesive by itself. As a result, the restorative dental material as directly bonded to a tooth will peel off, or, as the case may be, bacteria will penetrate into the bonded interface between the tooth and the restorative dental material to cause secondary caries and odontitis.
In order to solve this problem, various dental bonding methods which include previous application of some tooth surface treating agents to defective teeth to be restored have heretofore been described. Some reports disclose that such tooth surface treating agents improve the bonding strength between a tooth having been pre-treated with any of them and a restorative dental material applied to the surface-treated tooth. For example, (1) Journal of Dental Research Vol. 34, pp. 849-854, 1955 discloses that some acid etching primers improve the bonding strength of restorative dental materials to tooth enamel; (2) Journal of Dental Research, Vol. 63. pp. 1087-1089, 1984 discloses that a primer composition comprising glutaraldehyde, 2-hydroxyethyl methacrylate (hereinafter referred to as HERA) and water enhances the bonding strength of restorative dental materials to tooth; (3) JP-A-62-223289 discloses that a primer as prepared by adding an acid such as maleic acid, nitric acid or p-toluenesulfonic acid to an aqueous solution of HEMA improves the bonding strength of restorative dental materials to tooth enamel and tooth; (4) JP-A-1-113057 discloses that a primer as prepared by adding a salt of an acid to an aqueous solution of HEMA improves the bonding strength of restorative dental materials to tooth enamel and tooth; and (5) Materials and Instruments for Dental Use, Vol. 9. pp. 65-73, 1990 discloses that a primer as prepared by adding a monomer having an amino acid residue such as N-acryloylaniline or the like to an aqueous solution of HEMA improves the bonding strength of restorative dental materials to tooth enamel and tooth. In addition, (6) JP-A-3-240712 discloses a dental bonding composition as prepared by adding a polymerizable monomer having an acidic group and a curing agent to an aqueous solution of HEMA; and (7) JP-A-4-8368 discloses that adding an amino compound to the dental bonding composition in (6) enhances the ability of the composition to improve the bonding strength of restorative dental materials to teeth.
In particular, a dental bonding method of using a self-etching adhesive primer is an extremely excellent technique, as being easy to perform and provides a high bonding strength to the tooth. The adhesive primer for use in the method comprises an acid (including acidic monomers), a hydrophilic monomer and water, and the method of using it comprises applying the primer to the surface of a tooth and directly applying a bonding material thereto without washing and drying the primer-coated tooth.
However, the self-etching adhesive primer which does not require washing with water is problematic in that the polymerizable monomer will partly remain in the surface layer of tooth even though most of the solvent such as water and the like could be removed through drying with a dental air syringe after its application. The remaining monomer may be polymerized and cured together with the overlaid bonding material by irradiation of light. However, the adhesive primer contains low polymerizable monomers such as hydrophilic monomers and acidic monomers, which could not be polymerized all at once. In order to enhance its polymerizability, some means of improving the adhesive primer have heretofore been tried by adding thereto a photopolymerization initiator, which, however, could not produce the intended effect up to the present. As a result, the polymerization of the monomers in the bonding material (including the adhesive primer) applied to the surface of a tooth is insufficient, and, in a certain period of time after the restoration of the tooth with a restorative dental material, a crevice is formed between the tooth and the butted material to cause marginal leakage, or the butted material is peeled off. Such problems with the adhesive primer have heretofore been often pointed out. In particular, it is said that the problems are remarkable when the bonding material is irradiated by light for a short period of time.
Improving the polymerization curability of the adhesive primer end the bonding material could be attained in some degree by increasing the amount of the photopolymerization initiator in those compositions. Increasing the amount of the initiator too much in those compositions is problematic in that the initiator remaining in the cured products of the compositions will be much released out, since the initiator has no polymerizable group, and, in addition, the mechanical strength of the cured products is lowered and the cured products are discolored with the lapse of time. In that condition, aesthetic tooth crown repairing is impossible. For these reasons, adding too much initiator to the compositions is impracticable.
There is still another problem of secondary caries and odontitis that may be caused by the penetration of bacteria into the bonded interface between tooth and the restorative dental material applied thereto, in addition to the bonding durability failure in the bonding material used. The problem is often pointed out as serious.
For preventing the penetration of bacteria into the bonded interface, antibacterial dental bonding materials have been proposed. For examples JP-A-1-17107 discloses dental cement that contains an antibacterial agent. JP-A-2-16176 and B-198723 disclose a pre-treating agent for dental use that contains a quaternary alkylammonium salt. In these, they do not specifically refer to the antibacterial property of the pre-treating agent, but the quatemaryalkylammonium salt used will have antibacterial ability. However, the antibacterial agent and the quaternary alkylammonium salt have no polymerizable group, and will be therefore released out into the mouth after the dental bonding composition comprising any of them has been polymerized and cured on a tooth. Prior to their dental application, therefore, the antibacterial agent and the quaternary alkylammonium salt require complete safety evaluation. Another problem with them is that the antibacterial agent and the quaternary alkylammonium salt do not exhibit the antibacterial ability for a long period of time.
JP-A-6-9725 and 7-215814 disclose dental compositions containing an antibacterial polymerizable monomer and an acid group-having polymerizable monomer. The antibacterial property as referred to in these is the non-releasing antibacterial property of the polymerized (or cured) products of the dental compositions. Here, the cured products do not release the antibacterial component from them. These publications indicate that the cured products as formed through copolymerization of the antibacterial polymerizable monomer and the other monomer exhibit the antibacterial ability on their surface. Specifically, in the cured polymer products of the dental compositions proposed, the unpolymerized antibacterial compound is exposed out on the surface of the cured polymer, and it may attenuate the bacteria having adhered on the surface of the cured products, but could not k
Ebisu Shigeyuki
Imazato Satoshi
Nakatsuka Kazumitsu
Okada Koichi
Tsuchitani Yasuhiko
Kuraray Co. Ltd.
Szekely Peter
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