Bioactive glasses and their use

Details Bioactive glasses and their use Bioactive glasses and their use

1997-07-11

2000-04-25

Group, Karl

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

501 70, 501 7, 106 35, 4332121, 4332281, 633 16, C03C 3097

Patent

active

060544007

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to novel bioactive glasses with a large working range and controlled durability. Furthermore, the invention relates to the use of said bioactive glasses for tissue bonding purposes in the medical or dental field; for use in biotechnology; for controlled release of agents and for tissue guiding.


BACKGROUND OF THE INVENTION

The publications and other materials used herein to illuminate the background of the invention, and in particular, cases to provide additional details respecting the practice, are incorporated by reference.
In recent years intensive studies have been made on artificial materials called biomaterials to be introduced in the human body for repairing damages therein. The body conditions offer a severe environment for these materials. The combination of increased temperatures, salt solutions, destructive enzymes, organic acids capable of forming different complexes, proteins and dissolved oxygen in the body provides a most corrosive environment. The body is also extremely sensitive to foreign materials and easily shows signs of poisoning, rejecting reactions and allergic responses.
Only a very limited number of materials is accepted in soft or hard tissue as a substrate. These materials can e.g. be used as artificial implants supporting crowns and fixed bridges in dentistry, and in maintenance and augmentation of alveolar ridges (1). They may also be used as fillings in bone defects and in periodontal pockets, as capping materials in endodontics, and in orthopaedic, plastic, ear, nose and throat surgery (2). The materials can be used as granules and bulk materials to fill bone cavities and defects, and as coatings and bulk materials for artificial joints. The oral implants are in continuous contact with both hard and soft tissues, and the implant material should therefore develop an intime contact with both hard and soft tissue.
Biomaterials are defined as non-living materials that are used in the human body, and which are intended to interact with different biological systems. These materials can be either inert, resorbable or bioactive (1).
Inert biomaterials, e.g. carbon, some ceramics, metals, alloys and certain polymers, do not cause any measurable reaction in the body. The carbons include, for example, pyrolytic carbon, glassy carbon, carbon fibers and composites and they are used as heart valve stents and in orthopaedic surgery (1). Examples of inert ceramics are Al.sub.2 O.sub.3 and ZrO.sub.2. Metals and alloys used as biomaterials are e.g. stainless steel, titanium, tantalum and certain alloys. These metals and alloys are not surface active, i.e. a chemical bond does not develop between the material and the body tissue. Their durability is difficult to control in the body, and they are mainly used in orthopaedic and maxillofacial surgery (1).
Resorbable biomaterials are typically organic polymers, e.g. PGA (polyglycolic acid) and PLA (polylactic acid) which gradually degrade in the body and disappear (1).
Bioactive materials are surface active materials able to chemically bond to body tissue. This group includes bioactive glasses, glass ceramics and ceramics. The bioactive glass is amorphous. Bioactive glass ceramics are materials having crystalline particles embedded in the amorphous glass phase. Bioactive ceramics have a crystalline structure. When the bond between the bioactive material and the body tissue is a successful one, a layer of silica rich gel is found at the surface of the glass. The bone-bonding occurs when the build-up of bone-like apatite on top of this silica gel occurs (5,7,8,9). These bioactive materials are used as bulk materials, granules and coatings.
Ceramics as biomaterials can be either inert, resorbable or bioactive (1). Bioactive ceramics are e.g. calcium phosphates and aluminium calcium phosphates and they are used in orthopaedic surgery and as dental implants. The most common problems with these materials relate to crystallization. The crystalline structure makes them difficult to work and it is troublesom

REFERENCES:
patent: 5429996 (1995-07-01), Kaneko
patent: 5432130 (1995-07-01), Rheinberger et al.
patent: 5648301 (1997-07-01), Ducheyne et al.
patent: 5713994 (1998-02-01), Kramer et al.
patent: 5721049 (1998-02-01), Marolongo et al.
patent: 5735942 (1998-04-01), Litkowski et al.

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