TUBERCULOSIS.

Tuberculosis results from infection by a micro-organism called the tubercle bacillus. The essential lesion in tuberculosis is the development of tubercles either in a single organ or tissue (local tuberculosis) or throughout the body (general tuberculosis). The bacillus of tuberculosis may enter the body by means of (a) the digestive tract; by eating imperfectly cooked tuberculous meat, by drinking milk from tuberculous cows; and by direct infection from the sputum of phthisical persons. (b) By the respiratory tract; by inhaling dust impregnated with dried phthisical sputum. (c) By the skin by direct inoculation. It appears that tubercle is only rarely inoculated in this way and that even when inoculated it remains local and does not affect the general system. It is quite possible that the bacillus may affect the glands of the neck by having gained admission through a carious tooth.

In tuberculosis, as in all other microparasitic diseases, the vitality of the host must be lowered before the bacillus can gain a footing. The chief predisposing causes producing the necessary condition of lowered vitality are :

1. The strumous diathesis. This name is used to designate a general state of nutrition or constitution which is peculiarly suitable for the development of tuberculosis. Two distinct types are usually described; in the first known as the sanguineous or serous, the skin is fair and thin, the hair blonde or auburn, the features delicate, the eyes blue, the lashes long and silken, the intellect active and often precocious; in the second known as the melancholic or phlegmatic the general aspect is dull and heavy, the skin is thick, muddy and harsh, and the mind sluggish. In strumous subjects slight injuries are prone to produce inflammatory conditions characterized by great chronicity, feeble power of repair and tenddency to caseation of the inflammatory products. By some

pathologists these "strumous" inflammations are thought to be the result of actual deposit of tubercle and not of the general state of nutrition. Be this as it may, it is quite certain that some people (usually called strumous) although not actually tubercular are very prone to become so. It should be added that some authorities use the terms "struma" and "tuberculosis" as identical. This custom is to be regretted as it leads to confusion. It is better to apply the term "tubercular" to those who are actually afflicted with tuberculosis, and "strumous" to those who, although not actually afflicted, are in a condition of general health which predisposes to it. The term "scrofulous" largely used by the older writers is now used synonymously with "strumous" and had better be entirely discarded. The manner in which the strumous diathesis is produced is not fully understood; but it appears that it is often inherited from tubercular parents, and is apt to occur in the children of very young or very old, or dyspeptic or perhaps syphilitic parents.

2. Bad hygienic surroundings. damp, imperfect ventilation, etc.

Such as poor food,

3. Youth. Tuberculosis, although occasionally met with in old people, is almost entirely a disease of children and young adults.

4. Injury. The development of tubercular disease in a bone or joint is often determined by some slight injury which in a healthy person would produce no permanent evil result.

Structure of a Tubercle. Two varieties of tubercle are usually described, viz., the grey miliary tubercle and the yellow or caseous tubercle, the latter, however, is not a distinct variety, but is simply a degenerated caseated mass of miliary tubercle.

The miliary tubercle is globular in shape, varying in size from a pin's head to millet or hemp seed, and closely resem

bling a tiny nodule of cartilage in appearance, being hard and semi-translucent. When examined under the microscope it is found to consist of a central giant cell containing many nuclei; from the giant cell processes radiate out forming a reticulum or network in which are enclosed a number of cells. Those in the immediate vicinity of the giant cell resemble endothelial cells and are called "endothelioid"; the others are simply leucocytes, (see Fig. 9). A tubercle con

DIAGRAM OF A TUBERCLE.

In the centre is a giant cell containing tubercle bacilli and many nuclei. Around this are several endotheloid cells, outside which again are numerous leucocytes.

tains no blood vessels, and is consequently very prone to undergo caseous degeneration. By appropriate methods of staining, the tubercle bacilli can be demonstrated in the giant cell and the surrounding endothelioid cells. Various explanations of the structure of tubercle have been given by different authorities at different times. It seems probable that the

cluster of cells which constitute a tubercle are really phagocytic in nature, their aggregation constituting an attack upon the invading bacilli. The giant cells and endothelioid cells are probably of connective tissue origin, and the small round cells are derived from the blood.

There is scarcely any part of the body which is not at times affected with tuberculosis, but there are certain localities which are especially prone to be affected; these are the lungs, bones, joints, serous membranes and lymphatic glands.

The presence of tubercle in a tissue always sets up a certain amount of inflammatory reaction, in some cases, with the fortunate result that the tubercular deposit becomes encysted in a fibrous capsule, and is so rendered practically inert; it may then undergo caseation, and subsequent calcification. In other cases, the caseated tubercle may soften and form the focus of a chronic abscess, the necessary result being severe damage to the tissues; thus in bone disease caries usually results, in phthisis (pulmonary tuberculosis) the lungs become hollowed out with large suppurating cavities,

etc.

Symptoms. The symptoms of tuberculosis are necessarily extremely varied, as any organ or tissue in the body may be affected. It may be stated generally, that in the early stage of a tubercular lesion, the symptoms are chiefly those of irritation, and that in the later stages they are the result of destruction of tissue.

Treatment. The general principles of treatment of tubercular lesions are (a) to improve the general health in every possible way, so as to increase the resisting power of the tissues, (b) to provide mechanical and physiological rest for the affected part, and (c) to remove the diseased parts, when they are beyond the reach of natural repair, by excision, amputation, evacuation of abscesses, scraping, etc.

VULCANITE WORK.

By HARRY ROSE, L.D.S. Eng., Lecturer on Dental Mechanics, National Dental College.

[All rights reserved.]

(Continued from page 892).

GUM SECTION WORK.

Up to this point reference has been made only to the employment of the ordinary flat or vulcanite teeth, using, for the artificial gum, the pink rubber as sold at the depots.

If the patient does not expose the gums when talking, or laughing, this method of working answers very satisfactorily. Many patients, however, present themselves to our notice, who show not only the whole of the front teeth, but a large portion of the gums also. In such cases the presence of the rubber would be objectionable, so one finds it necessary to use what are known as gum section teeth." One cannot imitate the colour and translucency of the natural gums with an opaque substance such as hard rubber, but such a result can be accomplished by the use of gum

sections.

These sections represent teeth with the gums attached, and are made of dental porcelain. A set of fourteen gum teeth is usually divided into six sections, and great care is required in fitting them, not only to conceal the joints, or divisions between the sections, but also to get a perfect arch.

They should be mounted on a matrix plate, such as would be blown up in the Steam Swager, or on a plate sufficiently rigid that the sections are not liable to be displaced when the case is tried in the mouth. It is perhaps the best plan to fit