Physical Science Lesson 8 the Structure and Properties of Matter

The Structure and Properties of Matter The Structure and Properties of Matter - The Uses of Different Materials According to Their Properties and Structures

Objective  At the end of the lesson, lesson, you should be able able to relate the properties properties and structures structures of medical implants to their function.  Atoms and molecules molecules combine combine to form hundreds hundreds of thousands of different materials materials people use every day. The properties of these materials are influenced by their chemical structures. In turn, their properties determine their uses. In this lesson, you will focus on the materials used for medical implants. How are the  basic structures structures of implants implants related related to their their properties properties and uses? uses?

Last Updated: 08.12.16

Learn about it!  A medical implant is implant  is a chemical substance or a device used to replace, support, or improve a part of the human body. It should be stable, inert, heat-resistant, heat-resistant,  biocompatible,  biocompatib le, and long-lasting. Materials Used for Medical Implants In general, the materials used for implants can be categorized into three, namely, metals metals,, ceramics ceramics,, and polymers polymers.. Metals Metals have particles that are held together by strong metallic bonds. They are strong Metals have and durable. They are also good conductors of electricity because of the free flowing electrons.

 Alloys are combinations of one or more metals held together by metallic bonds. They contain atoms that have different sizes, which distort the regular arrangement of atoms. This distortion makes it more difficult for the layers of atoms to slide over each other, so alloys are harder and stronger than most pure metals.

Examples

 Alloys are often used for load-bearing implants because of their high strength, durability, and inertness. For example, stainless steel is one of the most common alloys used in orthopaedic implants, which are medical devices that can replace a missing joint or support a damaged bone.

Pure metals can also be used as implants. Pure titanium is best used as a pacemaker case. A pacemaker is a device which uses electrical impulses to regulate heart beats. Titanium is used because of its high resistance to corrosion and superior  biocompatibility.

Learn about it! Ceramics Ceramics are nonmetallic, inorganic solids with ionic or covalent bonds. They are commonly used in dental implants, such as crowns, cement, and dentures. They are hard, inert, and durable materials.

Example

Zirconia ceramic () is a crystalline solid held together by covalent bonds. The strong  bonds and the regularity of the crystalline structure give rise to the high strength and toughness of the material.

Zirconia is often used in restorative crowns because of its biocompatibility and smooth surface finish.

Learn about it! Polymers Polymers are molecules with a large number of repeating units of covalently bonded chain of atoms. They are versatile biomaterials with applications on facial, orthopaedic, and dental prosthesis.

Example  A common polymer used in implants is silicone. Silicone is polymerized siloxanes. It contains silicone-oxygen backbone chain with organic side groups bonded to the silicon atoms.

Silicone has a long polymer chain. The intermolecular forces of attraction between the chains are very strong. Therefore, silicone has high strength and durability. Also, its long chains can uncoil and slide past each other, making the material flexible. Because of its strength and flexibility, silicone is often used to replace original joint surfaces.

Try it! Interview a person that works in the medical field (e.g. nurse, doctor, dentist) or someone who has experience with medical implants. Try to find out the pros and cons of having medical implants and the proper ways of taking care of them.

What do you think?  What are the properties of materials used for bone replacements?

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Medical implants are substances or devices used to replace, support or enhance a biological part of the human body. Materials used for medical implants can be categorized into three types: metals, ceramics, and polymers. Metals for implants can be pure or alloys (combinations of one or more metals). They are held together by metallic bonds. Ceramics are made up of inorganic and nonmetallic atoms held together by ionic or covalent bonds. Polymers are molecules with a large number of repeating units of covalently  bonded chain of atoms.

Question 1  What are the basic uses of a medical implant? Incorrect!

3support organs and tissues4replace a missing body part Medical implants are tissues or devices that can replace a missing body part, monitor body functions, and provide support to organs and tissues. Next question

1attack foreign substances in the body 2monitor body functions Question 2  Which of the following is not a general type of medical implants? Correct!

2ionic Ionic is a type of bonding between a metal and a nonmetal. Next question

1ceramic3metallic4polymeric Question 3  Which of the following is an ideal property of a medical implant? Correct!

1 biocompatible Medical implants should be biocompatible. They must not be harmful or toxic to the living tissues. Next question

2 brittle3reactive4unstable Question 4  Which of the following compounds is an example of a ceramic implant? Correct!

4zirconia Zirconia is a nonmetallic inorganic material commonly used in dental implants. Next question

1zinc alloy 2titanium3silicone Question 5  Which of the following is not a metallic implant? Correct!

3silicone Silicone is a polymer that contains silicone-oxygen backbone chain with organic side groups bonded to the silicon atoms. Next question

1stainless steel2cobalt-base alloy 4titanium alloy  Question 6  Which properties of polymers make them usable as replacements of original joint surfaces? Correct!

1strength2flexibility  Strong and flexible polymers are best used f or replacements of dysfunctional joints surfaces.

Next question

3 brittleness4softness Question 7  Which properties of metals make them usable as pacemakers? Incorrect!

2reactivity 3stability  Stable, inert, and strong metals are used in making pacemakers, which are electronic biomedical devices that regulate human heartbeat. The device contain metallic electrodes that are in direct contact with the heart. Next question

1corrosiveness4electrical conductivity  Question 8  A person suffers from a neck injury. The doctor performs surgery by removing a damaged bone and filling the space with a substitute bone material. Screws and connecting rods are then used to secure the bones.

 Which of the following can be used as the material for the screws and rods? Incorrect!

1zirconia Titanium can be used as screws and connecting rods for neck and spinal injury because of its high resistance to corrosion and superior biocompatibility. Next question

2iron oxide3titanium4silicone Question 9 Cornea is the transparent front part layer of the eye. It can be damaged by diseases, infection, or injury. Some people need corneal implants to save their sight.

 Which of the following materials can be best used as artificial cornea? Correct!

3polymer  An artificial cornea must be transparent, biocompatible, and elastic. Among the choices, only polymers can be elastic and transparent. They can be used as cornea implants. Next question

1pure metal2alloy 4ceramic Question 10  A person loses several teeth in an accident.

 Which of the following pairs of materials is best used as teeth replacement? Incorrect!

1zirconia screw and silicone crown Titanium screws or cylinders act as replacement root for the missing teeth. Zirconia is then used as the dental crowns because of its smooth surface finish. Finish quiz

2stainless steel screw and titanium crown 3titanium screw and zirconia crown 4silicone screw and titanium crown