Compositions: coating or plastic – Coating or plastic compositions – Dental
Patent
1990-04-09
1993-06-29
Bell, Mark L.
Compositions: coating or plastic
Coating or plastic compositions
Dental
106124, 106137, C09K 300, C08L 8900
Patent
active
052230295
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to hardening materials for medical and dental use (hereinafter simply referred to as "hardening material") which may be used for a bone cement, a cement for dental use, and root canal sealing material.
BACKGROUND ART
In recent years, cements for dental use have contained hydroxyapatite (hereinafter referred to as "HAp and .alpha.-tricalcium phosphate [.alpha.-Ca.sub.3 (PO.sub.4).alpha.-Ca.sub.3 (PO.sub.4).sub.2 : hereinafter referred to as ".alpha.-TCP"] powder and an aqueous solution of polyacrylic acid as a setting solution. A hardened product is made by mixing, and kneading of the powder with the setting solution. However, polyacrylic acid, which does not react during the hardening, sometimes remains and thus, there exists a problem that a body may suffer damage due to elusion of the acid.
Also, for cements for dental use and root canal sealing materials, there have been known cement and root canal sealers in a series of zinc oxide eugenol in which eugenol is mixed to a setting liquid with a purpose of a pain-killing effect. However, cell toxicity has been reported with eugenol and also, a composite resin, that is a material for recovery of a tooth crown part, is disturbed by polymerization with eugenol. Therefore, a number of problems exist for the materials in the eugenol series for dental use.
There has been marketed a bone cement in which a polymer material such as polymethylmethacrylate (PMMA) and methylmethacrylate (MMA) is used. However, the following three problems have been known for this bone cement in which a polymer material is used. First, a bone tissue in a host, which is subjected to plugging up, does not directly combine with the bone cement and, when the bone cement is plugged up in a living body for a long period, there exists a problem such as loosening due to interposition of a fibril tissue. Second, since the temperature is raised to 90.degree..about.100.degree. C. with heat-generation during hardening, there exists a problem that surrounding cells are killed. Third, there exists a problem that elution of a monomer or an oligomer which has not reacted creates a bad effect on the bone.
On the other hand, there have been proposed a number of hardening materials which are furnished with .alpha.-TCP powder or tetracalcium phosphate powder (Ca.sub.4 (PO.sub.4).sub.2 0: hereinafter referred to as "4CP"), which are substances analogous to HAp that is a main inorganic component of body hard tissue, and also furnished with a setting liquid composed of a solution of a type of organic acid. For example, in Japanese official patent provisional publication of Showa 60-36404, there is described a material furnished with .alpha.-TCP powder and a setting solution of 1 M tannic acid. In Japanese official patent provisional publication of Showa 62-12705, there is described a material furnished with .alpha.-TCP powder and a 30.about.60% (w/w) aqueous solution of citric acid. Also, in Japanese official patent provisional publication of Showa 62-83348, there is described a material furnished with .alpha.-TCP powder and a 45% (w/w) aqueous solution of hydroxysuccinic acid. The .alpha.-TCP and 4CP are of high chemical reactivity and can be converted into HAp under the conditions similar to those in a body or a mouth.
The hardening materials described in the above publications have properties such that they cause almost no damage to a body, have the capability to form a hardened product analogous to body hard tissue, and have the capability to combine with hard tissue. A hardening material furnished with .alpha.-TCP or 4CP as a powder component and with a solution of an organic acid as a setting liquid component is very useful for medical and dental use, so that its practical use is very acceptable.
The hardening materials and their hardened products cause no damage to a body, but if a ratio between calcium phosphate powder and the setting solution (hereinafter simply referred to as "powder: liquid ratio") becomes large, the time for hardening becomes extremely sh
REFERENCES:
patent: 4524824 (1985-06-01), Shimokobe et al.
patent: 4608088 (1986-08-01), Lokken
patent: 4776890 (1988-10-01), Chu
patent: 4865602 (1989-09-01), Smestad et al.
patent: 5001169 (1991-03-01), Nathan et al.
Hata Seiko
Ishii Takashi
Oonishi Hironobu
Sugihara Fumihito
Suzuki Kaneo
Bell Mark L.
Einsmann Margaret
Nitta Gelatin Inc.
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