CERAMIC BIOMATERIALS

CERAMIC BIOMATERIALS

BY:ROHAN THOMAS VARGHESE

CHRIST UNIVERSITY

 

WHAT ARE BIOMATERIALS?

Biomaterials play an integral role in medicine today—restoring function and facilitating healing for people after injury or disease. Biomaterials may be natural or synthetic and are used in medical applications to support, enhance, or replace damaged tissue or a biological function. The first historical use of biomaterials dates to antiquity, when ancient Egyptians used sutures made from animal sinew. The modern field of biomaterials combines medicine, biology, physics, and chemistry, and more recent influences from tissue engineering and materials science. The field has grown significantly in the past decade due to discoveries in tissue engineering, regenerative medicine, and more.

Metals, ceramics, plastic, glass, and even living cells and tissue all can be used in creating a biomaterial. They can be reengineered into molded or machined parts, coatings, fibers, films, foams, and fabrics for use in biomedical products and devices. These may include heart valves, hip joint replacements, dental implants, or contact lenses. They often are biodegradable, and some are bio-absorbable, meaning they are eliminated gradually from the body after fulfilling a function.

 

CERAMIC BIOMATERIALS

WHAT ARE CERAMICS?

Ceramics are defined as “inorganic, non-metallic materials”. They are hard and brittle, great strength and stiffness, wear and corrosion resistance, and low density; ceramics work great with compressive forces, and are electrical and thermal insulators. Conversely, ceramics are also at risk of having cracks or other defects, and have been used less extensively than metals and polymers. They are used in dentistry, orthopedics, and as medical sensors.

WHY BIOCERAMICS?

Bioceramics are important in the biomedical field due to their chemical similarity to bone; and are ideal for surgical implants due to their thermal and chemical inertness, and have high strength, wear resistance, and durability. Ceramic biomaterials also stimulate bone growth and have low friction coefficients. They do not create strong biologically relevant interfaces with bones, but they do promote strong adhesions to bones. The main applications of ceramic biomaterials include:
-Joint/tissue replacement
-Metal coating to improve biocompatibility
-Resorbable lattice to provide a temporary structure that is eventually replaced by the body’s tissues

Bioceramics are not exclusively resorbable, they can also be bioactive, biodegradable, and soluble; and are also available as composites with a polymer component and microspheres.

TYPES OF BIOCERAMICS

-Bioactive: Bioglass/glass ceramic

-Bioresorbable: Calcium phosphate

-Bioinert: Alumina,zirconia,carbon

BIOACTIVE GLASS

Bioactive glasses are a group of surface reactive glass-ceramic biomaterials and include the original bioactive glass, Bioglass. The biocompatibility and bioactivity of these glasses has led them to be used as implant devices in the human body to repair and replace diseased or damaged bones. Most bioactive glasses are silicate based glasses that are degradable in body fluids and can act as a vehicle for delivering ions beneficial for healing. Bioactive glass is differentiated from other synthetic bone grafting biomaterials (eg. hydroxyapatite, biphasic calcium phosphate, calcium sulfate), in that it is the only one with anti-infective and angiogenic properties.

MEDICAL USES: bioactive glass was first used in a clinical setting as an alternative to bone or cartilage grafts in facial reconstruction surgery. The use of artificial materials as bone prosthesis had the advantage of being much more versatile than traditional auto transplants, as well as having fewer postoperative side effects.

There is tentative evidence that bioactive glass by the composition  may also be useful in long bone infections.

Bioactive glass as seen through an electron microscope

BIORESORBABLE

These are the materials that degrade in the body while being replaced with regenerating tissues.

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂)

Hydroxyapatite can chemically bond rapidly with bone due to chemical similarities, and was first used in the 70’s before being accepted as an implant material in North America in 1988. It supports bone growth without degrading, but has a mechanical strength incapable of performing long-term load bearing. The applications of hydroxyapatite include metal coatings and porous blocks or beads to fill bone voids.

Calcium Phosphate

Compared to hydroxyapatite, Calcium phosphate is easily absorbed into the body. Calcium phosphates are known for their porosity, and normally bond to bones through an apatite layer.Examples of Calcium Phosphate compounds are Amorphous calcium phosphate (ACP), Dicalcium phosphate (DCP, CaHPO4), and Tricalcium phosphate (α-TCP, Ca₃(PO₄)₂. Calcium phosphates are used in skin treatments, dental implants, orthopedics, and more.

BIOINERT

Bioinert ceramics are one type of the bioceramics and which classified based on their biological response in human body. Bioinert ceramics are usually defined as biologically inert nature or bioinert ceramics when implanted into biological system do not instigate an appropriate response or interact with the adjacent biological tissue . In other way known as, introducing the bioinert ceramics to the human environment will not exhibits any chemical reactions between the implant and bone tissue, also act as permanent replacements for damaged or diseased bone in orthopedic and dentistry surgeries . Bioinert ceramics are corresponds to first generation of biomaterials and widely used as  hip, knee replacements and dental  implant, crown etc due to astonishing characteristics such as high mechanical properties like tensile, compressive, hardness, low wear, toughness and good anticorrosion in biological fluid . There are mainly three type of  metal  based  bioinert  ceramics  such  as  alumina,  zirconia  and  titania  have  been  used  in musculoskeletal applications.

 

 FUTURE TRENDS

Bioceramics have been proposed as a possible treatment for cancer. Two methods of treatment have been proposed: hyperthermia and  radiotherapy. Hyperthermia treatment involves implanting a bioceramic material that contains a ferrite or other magnetic material. The area is then exposed to an alternating magnetic field, which causes the implant and surrounding area to heat up. Alternatively, the bioceramic materials can be doped with β-emitting materials and implanted into the cancerous area.

Other trends include engineering bioceramics for specific tasks. Ongoing research involves the chemistry, composition, and micro- and nanostructures of the materials to improve their biocompatibility.

 THANK YOU

 

 

 

 

 

 

 

 

 

Reference

 

·        Ceramic Biomaterials, by Jon Velez

·        National institute of biomedical imaging and bioengineering

·        Biomaterials and its applications,slideshare

·        Wikipedia

·        Researchgate

·        Youtube