Science & Technology in Action

10th Edition

Biocompatibility of Medical Devices

Boston Scientific

Medical devices that are implanted in the body generally come into contact with a variety of tissues and their interaction with each tissue type must be taken into account so that there is maximum benefit with minimal adverse reaction. This lesson considers some of the issues associated with biocompatibility.
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Contains the full lesson along with a supporting toolkit, including teachers’ notes.

Lesson excerpt

Introduction 
The practice of placing foreign objects into the human body has been around for an incredibly long time. One of the earliest instances of this was the insertion of fillings made from beeswax in a 6500 year old skull unearthed in Slovenia in 1911. These fillings were probably used to reduce temperature changes which would cause pain from the exposed nerve while eating. It was also common in ancient Egyptian high society to insert gold and precious stones into teeth in a very early example of purely cosmetic surgery. They also stapled lost teeth or false teeth made of ivory and other similar materials into gaps to improve both aesthetics and functionality. 

In the New World three teeth made from sea shell were found in an Aztec skull dating from around 600 AD. The shell had actually bonded with the jaw bone and was therefore a successful and functional implant. In more recent times, the famous astronomer and mathematician Tycho Brahe had a copper (probably gold for special occasions) prosthetic nose fitted after he lost the original in a duel over a mathematical formula in 1566. 

Biocompatibility 
Modern implant surgery began around the end of the nineteenth century with the introduction of single substance breast implants. A surgeon called Vincenzo Czerny (ca. 1895) successfully used body fat from a lumbar lipoma (fatty deposit on the lower back) to repair the symmetry of a breast from which he had removed a large tumour. A short time later another surgeon tried a breast implant using paraffin with disastrous consequences, thus alerting people to the importance of biocompatibility. Since that time very many materials have been used for implants with varying degrees of success. 

A substance or object is said to be biocompatible if it can exist together with living tissue, or a living system, without being toxic, injurious, or physiologically reactive and does not cause an immunological rejection; this can be classified as bioinert. In recent years biocompatibility has evolved to include the idea of fitting technology to enhance biological capabilities, as in the use of intraocular lenses and cochlear implants. Bioactive materials work in tandem with the body and allow the implant materials to bond with body tissues to form composite structures and behave as if they were natural materials. 

Quiz questions

  1. All substances placed into the human body produce an immune response false
  2. A defibrillator re-establishes the correct rhythm of the heart. true
  3. An antibody is a substance that causes the production of an antigen. false
  4. Neolithic man could put fillings into teeth. true
  5. Suppressor T cells stop disease causing cells multiplying in the body. false
  6. Cosmetic surgery is a modern invention. false
  7. Osseointegration is the placing of pieces of bone taken from one part of the body into another part. false
  8. Gutta percha an early form of rubber has been used for breast implants. true
  9. If two different metals are used in an implant they can in effect form a battery and cause one of the metals to corrode at an increased rate. true
  10. Dr. Per Ingvar Branemark was the first surgeon to implant a working pacemaker into a human. false