Conference reports

patients to car driving. They concluded that driving is a moderate stress for most cardiac patients, comparable with mental stresses such as arithmetic or examination, as well as stair climbing, and this stress is just slightly higher than at rest but consid- erably less than in most sport activities. Additional remarks included the use of nitrate as well as the use of beta-blockers by car-racing drivers who otherwise have heart rates constantly between 190 to 200.

V.E. Manoilov, Y.V. Stupin, V.I. Lebedev and N.A. Zotov discussed a two-channel ECG radio tele- metry system for application in swimming. The transmitter, an FM/FM system is also applicable for diving in fresh water down to approximately 2 m. They used the system for 35 different types of experiments.

J. MacGregor, R.F. Levy and T.G. Grassie pre- sented storage telemetry equipment using a 4 track tape recorder for data acquisition in rehabilitiation. They included in the discussion some specific prob- lems inherent to the diagnosis from patients in the unusual hospital environment, as well as cost aspects. An example showed the acquisition of ECG and body acceleration. N. de N. Donaldson had presented a paper on

encapsulation techniques for long terms implants. It is generally recognized that the penetration of body fluids into implanted devices is a major cause of failure and all synthetic polymers are permeable to water vapour. He described the failure mecha- nisms and methods developed at the MRC Neuro- logical Prostheses Unit in London for reducing the failure rate of devices during encapsulation and after implantation. This is one of the most neglec- ted areas of device production and it is good to see such painstaking work going into the investigation; the results of which will be utilized by all those working in the implant field. The fact that most of the contributors and audience at this conference were workers from Bio- logical and Zoological disciplines served as a refresh. ing reminder that Biological Engineering does really cover all the Life Sciences, and the pro- gramme was successful in bringing together for detailed discussions workers from many fields of biology and medicine. A book of abstracts is avail- able and a complete book of proceedings will published later this year.

Charles J. Amlaner, Jr. and

David W. Macdonald

ELEVENTH INTERNATIONAL BIOMATERIALS SYMPOSIUM

Clemson University, South Carolina, USA. April 28-May 1

The International Biomaterials Symposia origi- nated at Clemson University in 1969 and were held there annually until 1975 since when the combined meeting with the Society for Bio- materials has been held at various centres in the United States. For many of the members, and particularly for the immediate Past-President of the Society of BiomateriaIs, Dr. Francis Cooke, this year’s meeting was an opportunity to welcome the society back to its home town. The town of Clemson is a small community which is very much linked to the University. The University campus is a beautiful sweep of treelined lawns and lakes covering 600 acres. During the meeting there was no spare hotel accommodation for miles around and each day over 400 delegates from 14 countries converged on the conference centre. The delegates to the meeting reflected the inter- national nature of this society. Besides being inter- nationally supported it is also a society with a truly multi-disciplinary membership. Members include surgeons, dentists, orthopaedists, patho- logists, bacteriologists and other whose interests are clinically based and also materials scientists, polymer chemists, physicists, engineers and even

some of that vanishing breed who used to be known as pure scientists. There are also veter- inarians and medical men who manage to have a foot firmly in both fields. At no other meeting in my experience do so many different experts find common ground. The ‘common ground’ was exemplified in the various small groups sitting on the lawns and by the lake on the campus during the meeting. In one instance, there was held an official committee meeting of those responsible for the World Biomaterials Congress in 1980.

A scientific meeting is more than the sum of the place and the people, although if these two are right the success of a meeting is almost ensured. The programme after all is one of the reasons those people are together in that place. Each day began at 8 am with a tutorial address on one of the many aspects of “Good Laboratory Practices”. A measure of its importance in this as in the wider field of toxicology, was the presence, pencil at the ready, of people who do not usually rise and con- centrate at such an hour. Keynote addresses given by invited speakers covered dentistry, orthopaedics, materials science and wound healing. The speakers were Professor Ivar Mjar from Norway, Dr Vernon

298 J. Biomed. Engng. 1979, Vol. 1, October

Frankel and Dr David Buckley, from the USA and Dr George Winter from Great Britian.

The range of topics in the symposium sessions was wide including oral/dental, cardiovascular, ortho- paedic, maxillofacial and orthodontic application of materials as well as materials for transcutaneous use, wear testing and its clinical relevance, corro- sion problems, failure analysis of devices, tissue mechanics, tissue reactivity, tissue healing and biocompatibility and of course the seemingly ubi- quitous legislation and regulations. No mere cata- logue of session titles here but the opportunity to share recent advances on all fronts in this rapidly developing field.

Awards were made by the Society this year to honour people who are at the beginning and at the summit of their professions. Student awards were made for the first time and the Clemson awards for the seventh successive year. The two student awards went to a Japanese student, Masa- yuki Arakawa, for his studies on artificial red blood cells and to an American, Steven Gitelis. for

Conference reports

his work on total hip arthroplasty.

The annual dinner of the Society is the major social occasion at each meeting and it is during this dinner that the Clemson Awards are presented. These awards are made for outstanding contribu- tions to the field of Biomaterials. The award for contributions to the area of basic science went to Dr Jenifer Jowsey of John Hopkins University for her work in orthopaedics. The award for applied research went to another prominent worker in orthopaedics, Dr Victor Frankel, of the University of Washington. The third award was to Dr George Winter, lately of the University of London and was given in recognition of his major contribution to the scientific literature both in orthopaedic path- ology and in wound healing. The emphasis on orthopaedics was coincidental, but the Society has demonstrated its freedom from chauvinism, although they are now both working in the United States, Dr Jowsey and Dr Winter are both clearly British!

June Wilson

A selection of papers concerned with dental materials and wear are reported below:

The area of dental restoratives was the topic of a number of sessions. R.A. Draughn (Univ. of South Carolina) reported on studies of the compressive fatigue of composite materials as a function of the type size and volume fraction of filler particles. The results of this study indicate that: (i) fatigue lifetime of a composite is significantly reduced when the material contains a small volume fraction of relatively large (> 80 pm) filler particles, (ii) materials with lower volume fractions of filler have longer lifetimes in the test and (iii) fatigue life is improved when quartz filler is replaced by silicate glass.

The corrosion of dental restorative alloys was the topic of several presentations. M. Marek (Georgia Inst. Technology) reported critically on studies of amalgam by a variety of techniques, including: weight loss, electrochemical corrosion potential measurement, anodic polarization, free-corrosion rate measurement and controlled potential coulo- metry. The conclusion of this study is that electro- chemical techniques are best suited for evaluation of corrosion resistance and the controlled poten- tial coulometry method is the most reliable. In a related paper, the corrosion and tarnish of dental gold alloys was studies by T.K. Vaidyanathan and A. Prasad (NYU Dental Center and Jeneric Indus- tries). The results suggest that yellow dental alloys with high copper content have poorer corrosion and tarnish characteristics than the pure noble metal alloys. These results should be contrasted to those found in an investigation of the corrosion products from conventional a? i copper-rich dental

amalgams by S.J. Marshall and G.W. Marshall (Northwestern Univ.). Both clinically retrieved and laboratory specimens of amalgam were consistent with corrosion of Sn, Hg phase to give Sn, (OH)6C12 and SnO. Moreover, these products were much more prevalent in the conventional Ag-Sn alloy than in the Cu-admix amalgam. This same group also demonstrated that the creep of dental amalgam, which has been correlated with clinical performance, is dependent on the Cu6 Sn, content: higher creep is found for amalgams having lower Cu6 Sn, concentration.

A keynote address by D.A. Buckley (NASA Lewis Research Center- on, ‘Wear: Fundamental Mecha- nisms and Recent Advances’, stressed the impor- tance of a biomaterial’s history (surface character- istics, method of preparation, storage, temperature, etc.) in evaluation of its wear response. This topic was discussed further in a paper by G.B. McKenna and R.W. Penn (Natl. Bureau of Standards) which presented a theory of wear for biomedical polymers in terms of the concept of cumulative damage. In short, if the rate at which damage accumulates is dependent only on the current level of stress, then a simple empirical expression relating the stress history to time of failure may be constructed. The theory seems to be consistent with experimental data from polyethylene, polymethylmethacrylate and urethane-silicone systems. A large number of papers were devoted to the characterization wear in biomaterials. W.F. Bailey (Univ. of Connecticut) described a multistation pin-on-disc sliding wear apparatus for evaluation of

J. Biomed. Engng. 1979, Vol. 1, October 299