220 Australian Dental Journal, June, I964

tltantixt with i l l \ t~fficitwt i i i c ~ w of steriliz- ing iiistiwniwit s. However, the probltw of the sterjlr Iiantlpiec*e cannot be solved unless some other technique is used. The (Ii*y-lieat sterilizer coiild be a valuable iitljimct in this field. It is possible to w e such sterilizers for handpieces and I\iit\\y other iiistrnnients, if R well-planned It*chniqiie is ileveloped. The liaridpieces itre cleiliied, (lipped i n oil, and put i n a se;ilc.tl container which is then placed in the sterilizer for the appropriate time a t tlie right temperature. When the cycle is completed the container is removed and not opened until the handpiece is ivqiiired, The oil used, of course, must Iiave a flashlwint al)ove tlir tenil)ri*iitiii~~ raiigc. foi. sterilieiitioii diiriiig operation.

Letters to the Editor

Sir, 1’016 l ’ A CAN

My experience with the Porta Gas blow- pipe demonstrates that there is too small a margin in the melting of gold. A considerable improvement results if oxygen is added to the compressed a i r supply. The blowpipe designed for gas and air by the Porta Gas Company can be so used provided the main supply is a i r and not oxygen. I use a two-way adapter giving oxygen from a cylinder and compressed air in the other tube. In this way the main heating is done with gas and air, only letting in a small amount of oxygen towards the end of the operation. This immediately gives a temperature higher than the ordinary city gas and air types.

If oxygen enters alone a harmless bang blows out the flame, although of course there are blowpipes designed for Porta Gas and oxygen but such high temperatures are not needed iii dental work.

The adapter to th? oxygen cylinder and the two-way tube arrangement were made for me by A. D. L. Bulgin, 129 Buckland Road. Sydney.

STANLEY S. HAMILTON. 681 Pittwater Road, Dee Why. May 1, 1964.

(:Iieniical sterilizatioii is a possible alter- i i i i t ive procedure for some types of instru- nients bat since it is ii complicated aiitl time-coiisiirriing procediire i ts use is some- what limited. Tlie use of chemical solii- tions in tlie sterilization of hypodeimiic needles and syringes is contraindicatrd.

If antomatic sterilizers can be developed with a1)propriate safeguards to ensiiiw that tlierr can be no doiibt as to whether a Icirticular load has been subjected to sterilization, a tremendous advance will have been made. Since the uncertainty of rnaniial procedures rests upon the ~)i.obabil ity of Iinmnii error, such pro- cet1iii.e~ slioulcl be eliniinated w1icrc~vc.r poussible.

Sir, DENY’AL IZEb‘EARCH

It was my pleasure to accompany a team of research workers from the University of Oregon to the forty-second general meeting of the International Association for Dental Re- search held a t Los Angeles in March.

The programme ran for four days with three and four concurrent fifteen minute papers being read from nine in the morning till late a t night. The biological side of dentistry and dental materials were covered from many aspects.

The damage to pulpal tissue by opera- tive procedures and caries was intensively examined. Massler, Langeland and others presented beautifully prepared histological pictures of the pulp. While they cannot be said to be in agreement on the severity of the lesions seen in the pulp, when their work was viewed against the work of Zach and others i t was clear that our operative pro- cedures and various so-called sedative treat- ments are extremely insulting to the pulp; far more so than the original caries, except in the extreme. The work of these men further emphasized the great care we must take in instrumentation, particularly in close proxi- mity to the pulp. These histological studies also showed that the pulp has remarkable

Auatralian Dental Journal, .tune, I964

recuperative powers, for which we can be thankful; and also that the less the insult the quicker and more certain is the repair.

The “Materials” group is very active. A paper by George Wing of Sydney, read by Gunnar Ryge of Marquette, was well received, and it was interesting to see his amalgam etching technique for metalographic study being used by other workers.

Two unrelated Andersons from the United Kingdom read papers of interest. J. N. Anderson of St. Andrew’s read a paper on silicate while D. J. Anderson of Guy’s Hospital presented a study in control of sensitive dentine.

A new instrument, an electron probe, was used by Kame1 Asgar to investigate the micro- structure of amalgam. The probe is a minutely focused beam of electrons which can be con- centrated on a microscopic section of the sample. The secondary emission of X-rays can lie analysed to determine the composition of the surface at that point.

George Mumford, formerly of Sydney now a t Indiana, joined a n impressive symposium panel one afternoon and handled the subject of porcelain bonding to metal very capably.

Bernard Lilienthal, who is at present visit- ing the University of Illinois, wa8 also present.

I shared a room with David Mahler and Louis Terkla of Oregon and these men irttracted a large crowd to the room in the vvcmiiigs. These informal gatherings were as oiljoyable and informative as the organized sessions.

The meeting was a n interesting experience. There is a tremendous amount of work being done in dental research, some impressive some quite ordinary. There does not appear to be any great “break-through’’ in the offing, but there is a gradual fillingin of our knowledge of the complex field of dentistry.

BRUCE BUIINS. University of Oregon, Dental School, Portland 1, Oregon, U.S.A. April 22, 1964.

22 I

Sir, FOCAL INFECZ’ION

leecent correspondence culminating in letters in the February issue, on apparently quite different subjects, have had a n important effect, perhaps unrealized by their authors.

Without entering into the particular contro- versies with which they were concerned, I commend them on having drawn attention once more to the importance of dental infection in its relation to general health.

Over fifty years ago there was propounded a thesis which for many years was discussed and investigated under the name of “focal infection”. Let i t be freely admitted that some of the claims advanced during this era were

preposterous to the extent that it was aliiiost made to appear that all the ills of mankind were due to infected teeth. In the late 1930’s the “debunkers” moved in and, as so often happens, were, in order to prove their case, over-destructive in their criticism of a tre- mendous amount of honest investigation and clinical evidence. The pendulum acted in its usual fashion and swung too far.

Irrespective of the particular matters con- cerned, your correspondents have done a great deal of good in reawakening the dental pro- fession to its responsibility for the health of the patient.

135 Macquarie Street, Sydney. April 2, 1964.

F. E. HELMORE.

Sir, T H E FAMILY nENTIB1’

Animals, including man, are by nature born with all the elements necessary to grow and develop into normal healthy beings; beings with organs of special sensation that enable them to realize their environment and minutely examine and appreciate their surroundings. These organs form a cooperative unit consist- ing of the eyes, ears, nose, and mouth and make up the structural part of the facc. The teeth assume a n important part in this unit as they are concerned in the search, examination, and prehension of food, the cutting and grinding of food, and they act as a means of offence and defence. The import- ance nature attaches to teeth is expressed in the design and strength of skulls, in the structural changes that occur to serve the form and arrangements of the teeth of each particular animal, and in the durability and strength of tooth structures.

Teeth, the active instrument in the dentition, are mounted on a strong structure of bone- the skull. The design of skulls is that of a strong press, a press capable of withstanding and sustaining the stresses and strains exerted by the teeth. But this is not all for since the existence of most animals depends on the closest association and interaction of the teeth with the other organs in the unit of special sensation, the eyes, ears, and nose must be incorporated within the structure of this press: the face. The bony skeleton in the face of civilized man is degenerating. He alone in all creation exhibits defective eyes, ears, and teeth and requires the help of spectacles, hearing aids, and artificial teeth.

The importance nature attaches to teeth is certainly not shared by civilized man, for his only concern is with repair. There is little or no interest in preserving dental health or in development. The dental student is pre- pared for his life’s work in a dental hospital, a place where only those with tooth decay or in need of artificial dentures congregate, so the young graduate builds his practice on