Mrs. A. S.

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scribed above is a most serviceable instrument for this purpose. Extreme care must be observed in curetting the walls of a large cyst. The resorption of bone in the upper jaw may be so complete that the

The packing is removed after twentyfour hours, when the cavity is again lightly plugged, and the gauze tampon is changed about every fourth day until the cavity is completely lined with epithelium

from the ingrowing mucous membrane. The time involved in this continuous packing of the cyst may be materially shortened by using bone-wax. Mayrhofer has introduced a most ingenuous procedure for this purpose, and in the hands - of those who master the correct technique the results obtained are very gratifying. In using bone-wax or "bone plombe," as this material is known, the important point to be observed is to have a dry cavity, otherwise the bone-wax will not stick. Our method may be described briefly as

may be discharged. He is instructed to wash the cavity with warm salt water by means of a soft rubber ulcer-syringe. The rationale of using bone-wax for this purpose consists in completely obliterating the bony cavity with a sterile absorbable plug. The cavity will be filled with new bone tissue from the bottom up. It may take many months before the opening is fairly well obliterated, and more or less of a depression will always remain at the site of the operation. As the operation has been performed within the oral

follows: The patient, sitting in the dental chair, is placed in such a position that the long axis of the cyst cavity is in a perpendicular direction. The cavity is dried with gauze sponges, painted with iodin-acetone, and then coated with a thin film of sterile paraffin oil. The bonewax, which has been previously melted by placing the bottle containing it in very hot water, is now poured into the cavity until the latter is completely filled, and allowed to congeal. The surplus amount is wiped off. The patient reports about once a week for inspection. Usually in two or three weeks. the wax has to be removed, as it is loosened on account of the moisture secreted by the ingrowing mucous membrane. As soon as the cavity is completely lined with epithelium the patient

sistant, Dr. J. E. Aiguier, operated on 92 cases primarily for granulomas and chronic abscesses; 17 of these cases were cysts. The average time required for an ordinary granuloma operation by employing our present method of technique is less than ten minutes, not including the injection of the anesthetic.

In presenting the technique of root amputation to the general practitioner, the writer, in harmony with the maxim of the great Boerhaave "Simplicity is the seal of truth"-does not make any pretense of claiming originality for the method involved. He has endeavored to give credit to those who have assisted in the development of this most useful operation for the conservative treatment of those teeth which otherwise would eventually have to be sacrificed to the

forceps. Incidentally, this operation offers a rational procedure for the complete elimination of the most serious problem which confronts the practitioner of dentistry and medicine today, namely, oral focal infection. The writer merely reiterates the technique of this operation as it is practiced at present with most gratifying results in the institution with which he is connected, in the conviction. that this method once more vindicates the truism of the old medical axiom of Asclepiades: Curare cito, tute, et jucunde.

The writer is indebted to Mr. E. G. Van Valey for making the plain-line drawings, and to Messrs. A. E. and F. P. Croke and John Menzies for taking the photographs used in illustrating this article.

40TH AND SPRUCE STS.

T

HE term occlusion is relatively new to science. It was coined by the dental profession to convey an idea which had long been a subject of study by zoologists under the title of the mutual mechanical relations of the teeth of mammals. The studies of the mechanical relations of the teeth, now termed occlusion, the tooth forms, together with the anatomical structure of the jaws and skull in their relation to food habits and function, furnish the basic material upon which the science of orthodontia was founded.

From the evidence of these studies, reinforced with embryological data, a natural law, the law of occlusion, was recognized. There was seen to be, under normal conditions, a constant and ideal

relation of phenomena in the growth and development, racial and individual, of the masticatory apparatus. The order of sequence of the phenomena was seen to be so invariable that a definite conception of the normal was realized. If it were possible to follow in detail the evolution of the masticatory apparatus in an individual organism, none would be found that did not vary in some degree from the ideal. The ideal, the normal, embodied in the law of occlusion, is a conception of the normal growth and development of the dental apparatus derived from comparative studies of many organisms, fossil forms, and prehistoric skulls it is the uniformity seen in the diversity of organic forms. The significance of this should be fully appreciated,

as it is the very essence of scientific orthodontia.

The normal relation of the occlusal inclined planes of the teeth is but a phase of the law of occlusion. Occlusion is a tangible measure of conditions, and normal cusp relation one of the factors essential to the normal function of mastication. The normal growth and development of associated structures is as vital as normal cusp relation, and absolutely essential to it. The occlusion resulting from orthodontic treatment must often be a compromise of the ideal cusp relation, as in cases of missing or malformed teeth, or as the result of the inability to stimulate physiological cell activity in one or more of the supporting structures; in other words, because of factors beyond control the absolute is no more attainable in orthodontia than in other fields of biological science. From the above it is evident that a scientific diagnosis of a condition of malocclusion cannot be made from a plaster model alone, for orthodontia is concerned with occlusion in its relation to the organism as a whole.

As clinical experience and observations have gradually defined the field of orthodontia, the meagerness of our information has become more and more obvious. Although the innate principles and natural tendencies of growth and development conform to the same general laws in the human being as in other forms of life, it has been difficult to apply the conception of the law of occlusion derived from the older general morphology to orthodontic problems. The knowledge available has not been extensive enough to explain away some of the most common difficulties experienced in practice. In fact, it has become quite evident that the difference in the essential character and life-history of the human being from the lower and prehistoric organisms demands a more comprehensive knowledge of the law of occlusion.

Until quite recently animal morphology and physiology, as ordinarily presented, have been purely descriptive sciences. The material for the study of normal histology, anatomy, and paleon

tology has been of structures complete. Structures have been thought of as fixed in form, remaining the same throughout life. The forms of present-day organs have been attributed almost entirely to heredity, "while the vital activity of the living thing, so clearly shown in development and regeneration, has been ignored or forgotten."

Biological research of recent years has resulted in a transformation of the old ideas of morphology and physiology. They are being brought together on common ground. As experimental data have. pointed consistently to the fundamental unity of life phenomena, the truth has become more clear that the only possible justification for dealing with the constituents of an organism as if they were separate entities is in the convenience of study thus afforded. A knowledge of morphology or physiology, taken by itself alone, conveys little information of the process of development; but in the correlation of the different points of view pertaining to these sciences, i.e. physicochemical factors, physiological processes, morphological features, ecological correlations and adaptations and psychological events-in such correlation is revealed the vital phenomena of development in its real nature as a process essentially continuous.

We believe that orthodontia is in the main a study of growth and development; that it is a science of form development; that it seeks to know why structures take on the forms they do, and what is the nature of the factors which maintain the forms once they are established. We are concerned not so much with the forms as we are with the factors controlling the forms of the structures of the masticatory apparatus. We know now that knowledge limited to a description of the structure of the teeth and maxillary bones, together with the supporting and surrounding tissues, is not sufficient material on which to base the science of orthodontia-for such description shows merely the visible side of organic life, and leaves unknown the real processes of form development, form conservation, and their causes.

ORTHODONTIA A BIOLOGICAL PROBLEM.

To see nothing more in distinctive types than that each one is harmonious in design, and to be content with the assumption that the forms are due to a pre-established design and guiding force, which directs the working out of the design, will not carry orthodontia far in the field of science. The so-called "art requirements" in treatment was a valuable idea in emphasizing the harmonious character of the whole at the time when a realization of the normal was dawning in orthodontia, but it has little value now, since it conveys no conception of the nature of the factors involved in form development. It might be said that God makes the flowers grow, but who will deny that if something is known of the physico-chemical factors involved better blossoms are produced. If orthodontia is to survive as a science of human conservation it must be studied as a biological problem.

In the study of the individual organism it is logical to distinguish in the life of all parts two periods, in the first of which the part is formed prior to and independent of function, while in the second, differentiation and growth are dependent on functioning.

To W. Roux more than to any one man is due this conception of periods. of developments. E. S. Russell, (1) in review of Roux' work, says:

The first period is one of self-differentiation, in which the parts are formed in anticipation of functioning: and the second period is one of functional development, in which the organs are perfected through functioning, and only through functioning. The first period includes the directly inherited structures, growth and development taking place before they began their specific function. The second period includes the further differentiation and maintenance in their typical form of the parts laid down in the first period, and is brought about by the specific function of the part. This period brings to pass the finer functional harmonies of the organism.

The two periods of development cannot be definitely separated from one another, nor does the transition from one to the other occur at the same time in different

parts, and furthermore, in the transition both classes of conditions are effective, i.e. function is building on to the already formed.

The structures with which orthodontia is most immediately concerned are the teeth, bone, muscle, vascular, and ner

vous.

The teeth are one of the purest types of structure of the period designated by Roux as the first. Their form is directly inherited, and it is not known to be influenced in development to any appreciable extent during the normal life activities of the organism. Their form is evolved before they are brought within the influence of the specific function for which they exist, the function of masticating, and is not improved with use. the only change being from mechanical abrasion and disease. They are, in a word, non-functional structures.

Bone is of the second period, and is one of the clearest examples of functional structures. D. W. Thompson, (2) in his recent work entitled "Growth and Form,"

says:

we

In the biological aspect of the case, must always remember that our bone is not only a living, but a highly plastic structure; the little trabeculæ are constantly being formed and de-formed, demolished and formed anew. Here for once it is safe to say that heredity cannot and need not be invoked to account for the configuration and arrangement of the trabecula. If a bone be broken and so repaired that its parts lie somewhat out of their former place, so that the pressure and tension lines have a new distribution, before many weeks are over the trabecular system will be found to have been entirely remodeled, so as to fall in line with the new system of forces. This process of reconstruction extends a long way off from the seat of injury, and so cannot be looked upon as a mere accident of the physiological process of healing and repair. In cases of the transplantation of bone, for example, when a diseased metacarpal is repaired by means of a portion taken from the lower end of the ulnar, with astonishing quickness the plastic capabilities of the bony tissues are so manifested that neither in outward form nor inward structure can the old portion be distinguished from the new. About fifty years ago it was discovered by Herman Meyer (and