Biomateriales. Materiales y materias primas.

The Evolution of Biomaterials

Introduction to the Concept of Biomaterials

• In 1972, a popular science fiction series featured a protagonist with advanced prosthetics, highlighting early ideas about human enhancement.

• Over 35 years later, advancements in biomedicine and technology have significantly narrowed the gap between fiction and reality regarding implants.

Materials Used in Medical Devices

• The same materials used in space shuttle engines (titanium-aluminum-vanadium alloys) are also found in hip prostheses and dental implants (nickel-chromium alloys).

• These materials were initially developed for industrial applications but later adapted for medical use, becoming known as biomaterials.

Defining Biocompatibility

• Biomaterials are substances designed to interact with biological systems, aiding in the treatment or replacement of tissues or organs.

• Not all materials can be classified as biomaterials; they must be biocompatible—able to coexist with living tissue without causing adverse reactions.

Historical Context of Biocompatibility

• The concept of biocompatibility dates back approximately 9,000 years, illustrated by a man from Kennewick who lived with an arrowhead embedded in his hip.

• Biocompatibility is defined as a material's ability to be accepted by the body without causing irritation or inflammation.

Advances in Biomaterial Development

• Historically, biomaterials were repurposed industrial materials that met biocompatibility standards; now many are specifically engineered for medical applications.

• The first total hip replacement occurred in 1938; World War II accelerated surgical techniques and orthopedic developments due to practical experiences gained during wartime.

Case Study: Harold Ridley’s Innovation

• British pilots suffered eye injuries from aircraft windshields. Surgeon Harold Ridley utilized similar acrylic materials to create intraocular lenses for cataract surgery.

• Ridley's work on biocompatibility revolutionized ophthalmic surgery and improved millions of lives through enhanced vision restoration techniques.

Progression Through Decades

• In the 1950s, titanium-based alloys emerged for implants; previously stainless steel was common. Teflon was introduced for total hip replacements by the late '60s.

• By the '70s, porous materials became popular to promote bone growth around implants; significant improvements continued into the '80s with better surgical techniques.

Future Implications of Aging Population on Biomaterials

• Projections indicate that by 2050 there will be more individuals over 60 than under 15 years old. This demographic shift necessitates advancements in biomaterial technologies.

• With over 50 million people currently using some form of prosthesis, ongoing research is crucial for developing effective biomedical devices that integrate seamlessly with human tissues.

Conclusion: The Role of Gender Representation

Advances in Biomaterials and Their Applications

Overview of Biomaterials

• The discussion begins with various types of biomaterials, including maxillofacial implants, cardiac valves, artificial kidneys, and more.

• By the early 2000s, advancements in science and technology began to blur the lines between fiction and reality, exemplified by the story of Jess Sullivan, who became known as the "bionic man" after receiving a complex prosthetic arm.

Types of Biomaterials

• The four main classes of biomaterials are metallic, ceramic, polymeric, and composite materials. A significant focus is on ceramics due to their hardness and high-temperature resistance.

• Ceramics are poor electrical conductors; thus they are used as insulators in high-voltage lines. They were introduced into biomedical applications in the 1970s for non-load-bearing devices.

Properties and Applications of Ceramics

• Inert ceramics produce minimal biological reactions and are commonly used for bone defect filling in oral surgery and joint coatings.

• Bioactive ceramics create direct chemical bonds with tissues; hydroxyapatite is crucial for bone integration in implants.

Innovations with Titanium

• Titanium emerged from laboratory curiosity to a vital biomaterial that has significantly advanced medicine. It is widely used in aerospace technology due to its strength-to-weight ratio.

• The Airbus A380 utilizes titanium extensively; it was also pivotal in constructing Apollo capsules.

Characteristics of Titanium as a Biomaterial

• Discovered over 150 years ago but only commercially produced since 1946, titanium boasts high corrosion resistance while being lighter than steel yet stronger than aluminum.

• Its unique properties make it ideal for medical implants such as hip joints and dental pieces.

Manufacturing Processes for Metal Implants

• Metals like titanium alloys are essential structural components for load-bearing applications. They must meet specific requirements like biocompatibility and corrosion resistance.

• Despite many metals existing chemically, only a few are suitable for biomedical devices due to stringent requirements on their properties.

Commonly Used Metals in Biomedical Devices

• Stainless steels and cobalt-chromium alloys are among the most utilized metals alongside pure or alloyed titanium for implant manufacturing.

• The manufacturing process involves mineral extraction followed by purification to create alloys suitable for various implant forms.

Manufacturing Processes for Metal Implants

Overview of Metal Processing Techniques

• The process of metal casting and molding utilizes the lost wax method, machining, and forging, which involve applying pressure and temperature.

• Various manufacturing methods are necessary due to the differing processing requirements of implant alloys; surface treatments may include macro or microporous coatings to enhance bone integration.

Types of Alloys Used in Dentistry

• Dental alloys are categorized into two groups: precious metals (gold, platinum, palladium) and non-precious metals (silver-based alloys, nickel, copper, cobalt, iron, titanium).

• A fundamental requirement for these alloys is high corrosion resistance against saliva and other bodily fluids; gold was traditionally favored but is often combined with other metals for strength.

Applications of Precious vs. Non-Precious Alloys

• Non-precious metal alloys were developed as cost-effective alternatives to precious ones for crowns, fixed/removable dentures, implants, soldering materials, and orthodontic devices.

The Role of Teflon in Biomedical History

Historical Context of Teflon

• Teflon's connection to a significant biomedical milestone traces back to World War II when it was kept secret by the U.S. government after its invention in 1938 by DuPont.

• Known for its high chemical resistance and thermal insulation properties, Teflon was first used in total hip replacements by surgeon John Charl in 1959 but later abandoned due to failures.

Polymers in Biomedical Applications

• Since the late 20th century, synthetic polymers have gained popularity; they are derived from petroleum and offer versatility in forms such as fibers and films.

Specific Polymer Uses

• High-density polyethylene is utilized for drainage tubes and sutures due to its moldability; PVC serves both flexible (e.g., catheters) and rigid applications (e.g., pipes).

Notable Polymers

• Polymethyl methacrylate (PMMA), known commercially as Lucite or Plexiglas, is valued for its clarity and stability in intraocular lenses.

Innovations in Biomaterials

Development of Nylon

• Nylon was created by DuPont in the 1930s as the first artificial fiber; it revolutionized textiles while also being applied as a biomaterial for surgical sutures.

Versatile Use of Polydimethylsiloxane

• This polymer is crucial for various medical applications including catheters and pacemaker insulation due to its flexibility.

Case Study: Oscar Pistorius

The Impact of Composite Materials on Technology and Medicine

Understanding Composite Materials

• Composite materials are formed by combining two different materials to leverage the best properties of each.

• An example is fiberglass, which consists of tiny glass fibers encapsulated in polyester resin, resulting in a material that is much more resistant to breakage than its individual components.

• Fiberglass is used in various applications, from automobile bodies to surfboards.

Applications of Advanced Composites

• Kevlar is another composite known for its high mechanical resistance and low weight, commonly used in manufacturing bulletproof vests and vehicle bodies.

• In biomedical applications, composites are utilized for fracture fixation, bone cement, cartilage replacement, tendons, ligaments, and have been successful in creating prosthetic limbs.

Innovations in Biomaterials

• Carbon fiber combines high mechanical strength with low weight; it has replaced aluminum in racing bicycles due to these advantageous properties.

• The collaboration among engineers, medical professionals, chemists, physicists, dentists, and scientists has led to significant advancements in biomaterials since the first artificial heart was implanted by Domingo Liotta and Denton Cooley in 1969.

Future Prospects and Ethical Considerations

• Future developments may include new materials for sensors and artificial organs alongside the application of nanotechnology.