Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1995-10-10
1998-02-10
Azpuru, Carlos A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
424426, 623 11, A61F 228
Patent
active
057170061
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/FR95/00150 filed Feb. 8, 1995.
The invention relates to an injectable composition of a biomaterial for filling support tissues, dental tissues, bone tissues and osteoarticular tissues, which is intended to generate a resorption/substitution function.
Bone substitutes based on calcium phosphate particles and a biological adhesive are known from the prior art.
Thus, in Ann. Oto. Rhino. Laryngol. 101:1992, G. DACULSI et al. have described the efficacy of a microporous biphasic calcium phosphate composition for obliteration of the mastoid cavity.
The same authors have also reported the efficacy of a macroporous biphasic calcium phosphate composition for surgical repair of long bones (Journal of Biomedical Materials Research, Vol. 24, 379-396) and in vertebral arthrodesis (Clinical Orthopaedics and Related Research, 248, 1989, 169-175).
Moreover, JP 3 011 006 describes a cement for hard tissues which comprises a mineral phase made up of at least 60% alpha tricalcium phosphate and hydroxyapatite and/or a calcium monophosphate; and a liquid phase comprising carboxymethylcellulose.
However, on account of the excessive solubility of .alpha. tricalcium phosphate, such a composition has the disadvantage of not being sufficiently stable to permit a process of absorption/substitution of the hard tissue. In addition, such a composition is liable to generate harmful inflammatory processes. In addition, this mixture constitutes a calcium ionomer which is unsuitable for injection after a few minutes as a result of the mixture hardening from the moment it is made up. This combination has a two-fold instability, a volumetric contraction with release of water after several days, and especially a drop in the viscosity after sterilization of the mixture in an autoclave. It does not permit the formation of a "ready-to-use", sterile, injectable material.
The present invention has been set the object of providing a biomaterial composition which is charged in the mineral phase, is rehabitable and can be injected by the percutaneous route,
In particular, this biomaterial must have the following properties: over time without harmful inflammatory reaction.
This object has been achieved by the present invention, the subject matter of which is a composition for biomaterial for resorption/substitution of support tissues, dental tissues, bone tissues and osteoarticular tissues, which is made up of: .beta. tricalcium phosphate (A) and hydroxyapatite (B), in a ratio A:B of between 20:80 and 70:30, or calcium titanium phosphate (Ca(Ti).sub.4 (PO.sub.4).sub.6) (C), and polymer derived from cellulose.
The calcium titanium phosphate (CTP) of formula Ca(Ti).sub.4 (PO.sub.4).sub.6 is preferably of the Nasicon-like calci-metallo-phosphate type.
The mineral phase advantageously comprises 40% compound (A) and 60% hydroxyapatite (B).
It consists of a high-temperature sinter which is ground and sized to powder or granules whose particles have a diameter of 80 .mu.m to 200 .mu.m upon preparation of the composition. The choice of the particle diameter is guided by the resorption kinetics on the one hand, and by the rheology upon injection on the other hand. Particles with a diameter smaller than 80 .mu.m have resorption kinetics which are too rapid, and those with a diameter greater than 200 .mu.m pose problems in terms of rheology upon injection.
The viscoelastic polymer of the liquid phase is a nonionic polymer, in particular hydroxypropyl methylcellulose. A preferred hydroxypropyl methylcellulose has a molar substitution by methyl groups of 19 to 24% and by hydroxypropyl groups of 4 to 12%. It has a high degree of polymerization. The mean weight-average molecular weight is greater than 100,000 and is advantageously between 500,000 and 1,000,000.
The aqueous phase is determining as regards the rheological properties and consequently the viscoelasticity of the final composition which is intended to be injected.
To this end, the polymer concentration is advantageously between 0.5 and 4%, preferably 0.5 and 2%, by weight
REFERENCES:
G. Daculsi et al., "Scanning and Transmission Electron Microscopy, and Electron Probe Analysis of the Interface Between Implants and Host Bone", Scanning Microscopy, vol. 4, No. 2, 1990, pp. 309-314.
G. Daculsi et al., "Effect of the macroporosity for osseous substitution of calcium phosphate ceramics", Biomaterials, 1990, vol. 11, pp. 86-88.
N. Passuh et al., "Macroporous Calcium Phosphate Ceramic Performance in Human Spine Fusion", Clinical Orthopaedics and Related Research, Nov. 1989, No. 248, pp. 169-175.
G. Daculsi et al., "Macroporous calcium phosphate ceramic for long bone surgery in humans and dogs. Clinical and histological study", Journal of Biomedical Materials Research, vol. 24, 1990, pp. 379-396.
Daculsi Guy
Delecrin Joel
Grimandi Gael
Guerin Fran.cedilla.ois
Passuti Norbert
Azpuru Carlos A.
Centre National de la Recherche Scientifique (C.N.R.S.)
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