Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Nonwoven fabric – Including strand or fiber material which is a monofilament...
Utility Patent
1998-03-19
2001-01-02
Edwards, Newton (Department: 1274)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Nonwoven fabric
Including strand or fiber material which is a monofilament...
C442S365000, C442S414000
Utility Patent
active
06169046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an absorbable barrier membrane for use in guided tissue regeneration which is useful for regeneration of tissues of animals, including humans, and to a method for regeneration, using the absorbable barrier membrane, of a mandible, periodontal tissue, or defective tubulous bone, and particularly a defective tubulous bone which possesses a segmental bone defect in which both ends of the bone are in separate segments.
2. Description of Related Art
As methods for regeneration of bone, methods for filling or implantation of an absorbable cement or a sintered calcium phosphate as an absorbable ceramic has been known, in addition to guided tissue regeneration. Numerous patent publications and other literature exist with respect to these methods.
Japanese Language Publication (Kohyo), No. Hei 1-501289, corresponding to PCT Patent Application discloses a biological composite material containing contiguous pores, comprising a polymer and ceramics, and polylactic acid and calcium phosphate are disclosed as examples of the polymer and ceramics. An increase in alveolar protuberance is also disclosed. However, there is no apparent description about guided tissue regeneration. Also, there is no description about deactivation of a polymerization catalyst of the polymer.
Extensive literature exists regarding guided tissue regeneration in dentistry, and are disclosed in detail in “GTR No Kagaku To Rinsho (Science and Clinical Studies of GTR)”, written by Nakamura and Uraguchi, published by Quintessence Shuppan, Japan.
In particular, regeneration of the periodontal tissue for treating a periodontal disease is performed by preventing invasion of gum into the space at which the periodontal tissue should be regenerated, using a barrier membrane. As the barrier membrane, an unabsorbable polytetrafluoroethylene is mainly used. However, an unabsorbable membrane of polytetrafluoroethylene or the like has a drawback in that the burden on the patient is large because a surgery must be conducted in order to remove the membrane after the tissue is regenerated.
On the other hand, as the absorbable material, polylactic acid, a copolymer of lactic acid and glycolic acid, and the like have been reported. For example, Japanese Patent Publication, First Publication, No. Hei 2-63465 discloses a lactic copolyester such as a copolymer of lactic acid and &egr;-caprolactone, as a material for regeneration of periodontal tissue. However, there was a drawback in that the material is liable to deteriorate particularly during melt-molding because the polymerization catalyst is not deactivated. In addition, Japanese Patent Publication, First Publication, No. Hei 7-498 discloses a mixture of a piezoelectric polymer substance and inorganic micro particles. However, calcium phosphate was not described as an example of the inorganic micro particles and deactivation of the polymerization catalyst of the lactic polymer was not described.
Ossification includes membranous ossification and cartilaginous ossification. It is known that the cranium, mandible, clavicle, etc., are formed by membranous ossification, whereas tubulous bone (e.g., the humerus, femur, tibia, fibula, carpus, ulna, etc.) is formed by cartilaginous ossification. Regeneration of bone by guided tissue regeneration has been studied with respect to the mandible, mainly, and application of guided tissue regeneration to the tubulous bone formed by cartilaginous ossification has rarely been performed.
As an application of guided tissue regeneration to tubulous bone, application to an epiphysis defect is described in Japanese Patent Publication, First Publication, No. Hei 7-236688; however, this bone defect is not in segmented form.
Examples of use in segmented tubulous bone are disclosed in a study by Farso-Nielsen, et al., (Journal of Dental Research (special issue), Vol. 70, page 577, 1991) and a study by Lu Shibi, et al., (Chinese Medical Journal, Vol. 109, No. 7, pages 551 to 554). In the case of Farso-Nielsen, et al., a test using an absorbable polyurethane membrane was performed. However, since sufficient regeneration of bone cannot be performed by only using the membrane, decalcified bone must be used in combination. In the case of Lu Shibi, et al., since an unabsorbable silicone membrane is used, the membrane must be removed after regeneration of the bone.
As guided tissue regeneration for regeneration and bridging of a severed peripheral nerve, use of a tube of polyglycolic acid is known. For example, Japanese Language Publication (Kohyo), No. Hei 1-503204, corresponding to PCT Patent Application discloses mainly a device for nerve regeneration; however, there is a drawback in that the device is liable to degrade during molding because the polymerization catalyst is not deactivated.
That is, conventional bioabsorbable membrane of polylactic acid, a copolymer of lactic acid and glycolic acid, or the like had a drawback in that the heat stability, processability, and reproducibility are inferior because the polymerization catalyst is not deactivated in the production of the polymer, and furthermore, the storage stability is also inferior because a monomer formed during the melting acts as a decomposition catalyst of the polymer. If an inorganic powder is melted and is kneaded, together with a conventional lactic copolyester whose polymerization catalyst is not deactivated, a drastic decrease in molecular weight and a drastic increase in monomer formation occurred.
In addition, a conventional bioabsorbable membrane such as polylactic acid or a copolymer of lactic acid and glycolic acid had a drawback in that it was too rigid and too brittle to be used as an absorbable barrier membrane. This drawback has caused further problems in that the absorbable barrier membrane breaks easily when the membrane is implanted into a defective portion in an alveolar bone, tibia, or the like. Furthermore, since a composite material of such a membrane and calcium phosphate is even more brittle, such a composite material could not be used as a barrier membrane in view of its physical properties.
SUMMARY OF THE INVENTION
The objects of the present invention are to provide an absorbable barrier membrane for guided tissue regeneration which is useful for regeneration of animal tissues, including those of humans, the absorbable barrier membrane being superior in heat stability, processability, reproducibility, storage stability, bioabsorbablity, and tissue regeneration effects, and to provide a method for regeneration, using the absorbable barrier membrane, of a mandible, periodontal tissue, or defective tubulous bone, and particularly a defective tubulous bone which possesses a segmental bone defect in which both ends of the bone are in separate segments.
The present inventors have found that a barrier membrane which has suitable elasticity and rapid tissue guiding capability and is superior in processability, reproducibility, and storage stability, may be obtained by using a combined material of a lactic copolyester whose polymerization catalyst is deactivated, and calcium phosphate having a bone guiding capability. Thus, the present invention has been accomplished. That is, the present invention includes:
(1) an absorbable barrier membrane for guided tissue generation, comprising a lactic copolyester in which a polymerization catalyst is deactivated, as an essential component;
(2) an absorbable barrier membrane described in (1), further comprising a calcium phosphate;
(3) an absorbable barrier membrane described in (1) or (2), wherein the polymerization catalyst of the lactic copolyester is one which has been subjected to a deactivation treatment using a chelating agent and/or an acidic ester phosphate;
(4) an absorbable barrier membrane described in any one of (1) to (3), wherein the lactic copolyester contains a structural unit derived from lactic acid and a polyester structural unit derived from dicarboxylic acid and diol, and the content of the polyester structural unit derived from dicarbox
Kakizawa Yasutoshi
Kikuchi Masanori
Koyama Yoshihisa
Miyairi Hiroo
Shikata Toshiki
Armstrong, Westerman Hattori, McLeland & Naughton
Director-General of National Institute for Research in Organic M
Edwards Newton
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