Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
1999-04-23
2001-05-08
Azpuru, Carlos A. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C523S114000, C523S115000, C523S116000, C623S016110
Reexamination Certificate
active
06228386
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to compositions and methods useful to repair osseous defects, for example, in various parts of the body of a human or animal. More particularly, the invention relates to compositions including, and methods using such compositions, bioactive, biocompatible glass particles having defined chemical make-ups and particle size distributions which provide substantial osseous defect repair benefits and substantial cost benefits.
Glass particles have previously been suggested for repairing osseous defects. For example, Low et al U.S. Pat. No. 4,851,046 discloses using glass particles having a broad size distribution of 90 to 710 microns to repair periodontal osseous defects. This patent discloses that a mixture of glass particles having a larger or wider particle size range, including particles having a size range of 500 to 710 microns, might produce a clinically more desirable product. This patent discloses glass particle compositions having a wide overall size distribution and including particles of 500 to 710 microns in size.
Schepers et al U.S. Pat. No. 5,204,106 discloses compositions of glass particles at least 95% by weight of which have sizes between 280 and 425 microns for use in a process for filling an osseous defect or deficiency. This narrow particle size distribution adversely impacts the cost of the product. Moreover, this patent make clear that if the particles are too small, that is smaller than 280 microns, the particles have a tendency to break, and if these particles are present in excessive amounts, that is 5% or more by weight, the desired performance is not achieved. Thus, although the narrow particle size composition is more costly, this patent concludes that such narrow size distribution provides enhanced performance benefits.
Ducheyne et al U.S. Pat. No. 5,658,332 discloses methods for forming osseous tissue in defect sites in the appendicular skeleton or in sites exhibiting reduced metabolic state using glass particles having a size from 200 to 300 microns. This narrow particle size distribution, which is even more narrow than disclosed in the above-noted Schepers et al patent, disadvantageously increases the cost of the product.
It would be advantageous to provide a product which is effective in repairing osseous defects, meaning to include osseous deficiencies as well, and which is cost effective to produce and use.
SUMMARY OF THE INVENTION
New compositions and methods useful to repair osseous defects have been discovered. Such compositions provide performance benefits, for example, in terms of effectiveness in repairing osseous defects and/or in being able to be effectively handled or manipulated prior to such use relative to many of the prior art compositions. In addition, since the present compositions have a relatively broad particle size distribution range, the present compositions are cost effective to produce and use, often more cost effective to produce and use relative to prior art compositions. Moreover, the present compositions can be easily produced and used, for example, employing conventional techniques which are well known in the art.
In one broad aspect of the present invention, compositions useful to repair osseous defects are provided and consist essentially of particulate bioactive and biocompatible glass. The present glass particles have the following chemical make-up:
Silica
40 to 58% by weight
Calcia
10 to 32% by weight
Soda
10 to 32% by weight
Phosphorus pentoxide
2 to 10% by weight
In addition, the particles have the following size distribution:
53 microns to less than 297 microns
20% to 65% by weight
297 microns to less than 350 microns
20% to 45% by weight
350 microns to less than 420 microns
15% to 40% by weight
The particle size distributions set forth herein are based on a measurement using calibrated sieves.
The relatively broad particle size distribution of small and intermediate sized particles, in accordance with the present invention, has been found to provide very effective osseous defect repair, to be easily handled or manipulated during use, and to be cost effective to produce, for example, when compared to the compositions of the prior art, as described elsewhere herein. Such findings are indeed surprising since such prior art is directed to compositions which include a broad particle size distribution including particles of 500 to 710 microns in size, or to compositions which include very narrow particle size distributions. The present compositions are different from these prior art compositions, and provide benefits which are substantial and unexpected from the prior art.
Any and all features described herein and combinations of such features are included within the scope of the present invention provided that the features of any such combination are not mutually inconsistent.
These and other aspects and advantages of the present invention are apparent in the following detailed description and claims.
DETAILED DESCRIPTION OF THE INVENTION
The present compositions include bioactive and biocompatible glass particles including a combination of silica (SiO
2
), calcia (Cao), soda (Na
2
O) and phosphorus pentoxide (P
2
O
5
). Further, such particles have particles size distribution ranging from 53 microns to 420 microns or more.
As noted previously, in one broad aspect of the invention, the particulate bioactive and biocompatible glass has the following chemical make-up:
Silica
40 to 58% by weight
Calcia
10 to 32% by weight
Soda
10 to 32% by weight
Phosphorus pentoxide
2 to 10% by weight
and the following particle size distribution:
53 microns to less than 297 microns
20% to 65% by weight
297 microns to less than 350 microns
20% to 45% by weight
350 microns to less than 420 microns
15% to 40% by weight
Measuring particle size distributions using calibrated sieves may result in a limited degree of variation. For example, the sizes of glass particles in the present compositions may vary by an amount of ±1% or less, or ±3% or ±4% or even ±6% of the nominal particle size. Such variations in the nominal sizes of the glass particles of the present compositions are within the scope of the present invention.
In one embodiment, the amount of particles from 53 microns to less than 297 microns is 20% to 50% by weight.
The present compositions have been found to be very effective in repairing osseous tissue defects (and deficiencies), for example, by implanting the present compositions in such defects.
The present compositions provide for effective bone fill in the osseous defects filled with the compositions. In addition, the speed of bone fill in the defects filled with the present compositions is increased relative to various prior art compositions. Further, more excavations are apparent in the particles of the present compositions, for example, relative to many of the prior art compositions. As used herein, the term “excavation” is defined as the formation of a central cavity through the interior of a particle at the time of full reaction of the particle which includes gelation and calcium phosphate layer formation. Excavation is evident by observation of cells within a particle. Excavations in a composition are advantageous, for example, to increase the amount of bone fill and the speed of bone fill in an osseous defect implanted with the composition.
The chemical make-up of the glass and/or the particle size distribution may be varied in accordance with the present invention to advantageously provide benefits in the specific application in which the present compositions are used. Such compositions, in generally, can be characterized as including small and intermediate sized particles which are often more effective in repairing osseous defects relative to prior art compositions and which are often more cost effective to produce relative to prior art compositions.
Preferably, the glass of the present compositions has the following chemical make-up:
Silica
42 to 54% by weight
Calcia
15 to 29% by weight
Soda
14 to 30% by we
Azpuru Carlos A.
Stout, Uxa Buyan & Mullins, LLP
Unicare Biomedical, Inc.
Uxa Frank J.
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