Dentistry – Method or material for testing – treating – restoring – or...
Reexamination Certificate
2000-07-03
2001-12-25
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
C623S011110, C623S013110, C623S016110
Reexamination Certificate
active
06332779
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an osteogenic osteoimplant made up of, at least in part, elongate bone-derived elements for use in the repair, replacement and/or augmentation of various portions of animal or human skeletal systems. More particularly, this invention relates to the use of an implant made up of a coherent mass of elongate bone-derived elements optionally in combination with bone powder. The elongate bone-derived elements and/or bone powder may be undemineralized bone, partially or fully demineralized bone, or any combination thereof. The method of the invention herein is especially useful in periodontal applications, e.g., guided bone regeneration; plastic and reconstructive surgery, e.g., where the contour of the bone must be modified; and filling of cranial defects; though other skeletal applications are also envisioned.
The use of pulverized exogenous bone growth material, e.g., derived from demineralized allogenic or xenogenic bone, in the surgical repair or reconstruction of defective or diseased bone is known. See, in this regard, the disclosures of U.S. Pat. Nos. 4,394,370, 4,440,750, 4,472,840, 4,485,097, 4,678,470, and 4,743,259; Bolander et al., “The Use of Demineralized Bone Matrix in the Repair of Segmental Defects”,
The Journal of Bone and Joint Surgery
, Vol. 68-A, No. 8, pp. 1264-1273; Glowacki et al, “Demineralized Bone Implants”,
Symposium on Horizons in Plastic Surgery
, Vol. 12, No. 2; pp. 233-241 (1985); Gepstein et al., “Bridging Large Defects in Bone by Demineralized Bone Matrix in the Form of a Powder”,
The Journal of Bone and Joint Surgery
, Vol. 69-A, No. 7, pp. 984-991 (1987); Mellonig, “Decalcified Freeze-Dried Bone Allograft as an Implant Material In Human Periodontal Defects”,
The International Journal of Periodontics and Restorative Dentistry
, pp. 41-45 (June, 1984); Kaban et al., “Treatment of Jaw Defects with Demineralized Bone Implants”,
Journal of Oral and Maxillofacial Surgery
, pp.623-626 (Jun. 6, 1989); and, Todescan et al., “A Small Animal Model for Investigating Endosseous Dental Implants: Effect of Graft Materials on Healing of Endosseous, Porous-Surfaced Implants Placed in a Fresh Extraction Socket”,
The International Journal of Oral & Maxillofacial Implants
Vol. 2, No. 4, pp. 217-223 (1987).
More recently, processed bone has been developed into new shapes for use in new surgical applications, or as new materials for implants that were historically made of non-biologically derived materials.
U.S. Pat. No. 5,556,430 describes the use of a continuous sheet of demineralized bone or partially demineralized bone, however, the sheet must be sufficiently flexible, therefore sacrificing strength, in order to conform to the skeletal site to which it is applied.
However, the prior art demineralized bone products have proven to be unsatisfactory for applications requiring a thin osteogenic material capable of displaying a variety of properties. Commonly assigned U.S. application Ser. No. 09/610,026 filed on even date herewith and incorporated herein by reference discloses a new osteogenic implant.
In one embodiment, the material is thin and conforming, i.e., able to be shaped closely to the exterior of bony surfaces, thereby minimizing stress on the overlying soft tissues. In a different embodiment, the material is form holding, i.e., able to maintain its three-dimensional architecture even after rehydration and deformation prior to or during implantation. This new thin osteogenic material capable of displaying a variety of properties is useful in surgical applications that previously were difficult to successfully treat, e.g., periodontal defects.
BACKGROUND OF THE INVENTION
Membrane barrier devices are used as physical barriers to epithelial cell migration in the treatment of periodontal defects through the principles of guided tissue regeneration (GTR). The concept of guided tissue regeneration was developed by Nyman, S. et al. “New attachment formation by guided tissue regeneration.”
J. Perio. Res
., 1987, 22(3) 252-254 and in practice involves the use of a biocompatible material capable of separating two cell populations in vivo. The principle is as follows: When an empty space is created in a living tissue, it is filled by the most rapidly multiplying cell line adjacent to this void, unless access is deliberately limited to a single cell type, which will then be the only one to colonize the void to be filled. The principle is utilized in guided tissue regeneration for directing the repair of damaged tissues in the manner desired by the clinician. Thus, for example, in the case of periodontology, it is very difficult to repair damaged periradicular ligamentaous tissue. In fact, during the periodontium healing process, the epithelium regenerates more rapidly than the ligament and tends to take its place. The guided tissue regeneration technique used in this case consists in isolating the region normally occupied by the ligament, so as to make it inaccessible to the epithelium. This operation can be performed with a biocompatible material implanted in the tissues.
The materials currently in clinical use, with a few notable exceptions, e.g., titanium-reinforced membrane and calcium sulfate (Capset), are non-rigid, non-space maintaining, and do not possess osteoinductive properties. Such currently available materials, e.g., resorbable barrier membranes, are typically fabricated from collagen or polymers and are generally understood to be inferior to the non-resorbable materials due to premature degradation of the barrier properties. The notable exceptions, titanium-reinforced membrane and calcium sulfate (Capset), are not without their limitations.
Although titanium serves to add rigidity and volume beneath the membrane, this material must be removed and is technically demanding to implant and maintain. Calcium sulfate, when placed atop a bone graft material during operative repair of a periodontal lesion, sets up (hardens) intraoperatively and is resorbable. However, calcium sulfate does not posses osteoinductive properties and its efficacy, as a barrier to epithelial migration or oral contaminants, is uncharacterized. U.S. Pat. No. 5,700,479 describes an element and method for selective regeneration of any tissues in a living human or animal body tissues subjected to healing. U.S. Pat. No. 5,032,445 describes the use of a biocompatible porous material, such as expanded polytetrafluoroethylene (PTFE), for separating the gingival tissue from the tooth surface in an area where periodontal disease is present, or for treatment of bony defects. Therefore one object of this invention is to provide a method of using an osteogenic barrier membrane which possesses physical membrane attributes while avoiding reoperative removal procedures.
In addition to the periodontal application, any bone or bone area throughout the whole body available for surgical intervention can be treated by using the method of the present invention. The aim of the treatment might be a predictable filling out of bone defects of different sizes and shapes in the edentulous jaw bone or adjacent to teeth or bone-anchored implants, as well as, bone defects anywhere else within the body such as in the maxillofacial bones, in the skull bones, in the long bones, in the hand and foot bones, and in the back bones. The defects might have well-defined borderlines or successively pass into the surrounding bones and their bottom and wall surfaces can contain more or less of compact (cortical) bone. The defects might be so narrow as to be defined as bone depressions rather than bone defects. In fact, there are many sites where the bone surface to be chosen for regeneration is flat or convex rather than concave, but where there are strong indications for building up rather than filling out bone. The bone defect can also include a fracture optionally in combination with skull bone and/or jaw bone defects. The method of the present invention may also be used in situations where there are indications for elongation (or shortening) of bones, for instance
Boyce Todd M.
Kaes David
Salkeld Samantha
Scarborough Nelson L.
Dilworth & Barrese LLP
Lucchesi Nicholas D.
Osteotech Inc.
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