keeps pace with the destructive process taking place in the subjacent tissues. The result is the formation of a pocket, bounded at one point by the extreme limit of bone necrosis, and at the other by the margin of the gum. Between these two points there may be and often is a pocket of considerable depth, depending upon the amount of bone loss and gum recession.

Laterally these pockets are bounded on the one side by the overlying soft tissues and on the other by the cementum with its investment of necrotic pericementum and calculary deposit. Into these pockets, even in their earliest beginnings, the bacterial flora of the mouth finds its way. These organisms are purely secondary invaders, having no direct etiological relationship to the disease. Comparative studies of the bacterial flora of these pockets show that they do not differ qualitatively from that of the normal mouth. There is, as might be expected, great quantitative difference, this being explained by the fact that these conditions are more favorable to bacterial growth and development than is the healthy mouth. This flora is a mixed infection of great complexity.

The pus-producing cocci are present in large numbers, and in every known strain. Spirochetes, fusiform bacilli, and organisms of unknown types are also present, as is the amoeba. There is no evidence that any of these sustain a direct causal relationship to the disease. They do, however, give rise to one of its characteristic symptoms of pus, for without infection there would be no discharge from these pockets. It is true, there are cases in which there seems to be no pus. This does not necessarily mean that there is none. This apparent absence may be due to shallow or wide open pockets, as a result of which the pus is washed away by the oral secretions as rapidly as it is formed, or it may be due to an inactive phagocytosis, or both. That bacterial growth is less in such cases, or that it is less pernicious in its influence, seems improbable. These bacteria give rise also to metastatic infections of the gravest import, in many

instances contributing to the ill health and inefficiency of the patient, and not infrequently are the indirect cause of death. About one thing there can be no doubt, namely, their potentiality for evil is an inherent quality dependent only for its exercise upon the virulence of the organisms and the resistance of the host.

This, briefly, is a picture of some of the pathological changes taking place in the investing tissues of the teeth as a result of the initiation and development of pyorrhea alveolaris-changes which, unless observed in their earliest beginnings, will eventuate in the loss of the teeth, with possible secondary infections of a serious nature.

ETIOLOGICAL FACTORS IN PYORRHEA.

For convenience sake, the etiological factors of pyorrhea may be divided into two groups, predisposing and exciting. Such a division is necessarily an arbitrary one, since it is impossible in all cases to draw an accurate line between the two, as under certain conditions a single factor may at once predispose and excite. An unsanitary mouth may be said to be an example of this kind. It is desirable, therefore, that every case presenting for treatment be carefully studied with a view to determining as accurately as possible the factors which have caused it; for no case can be intelligently treated in which there is not a clear comprehension of all the forces which have entered into its causation. It must be obvious that unless these are recognized and removed, all efforts. at correcting the pathological changes which have taken place in the tissues themselves will be more or less futile.

PREDISPOSING CAUSES.

Among the more common predisposing causes may be mentioned systemic diseases, localized malnutrition, frail bony investment of the teeth, and occlusal trauma. It should be remembered, however, that it is not by any one of these conditions that pyorrhea is caused,

but by a combination of them, including those in the exciting group.

SYSTEMIC DISEASES.

Little of an exact nature is known regarding the relationship between certain diseases, such as tuberculosis, diabetes, syphilis, etc., and pyorrhea. That diseases such as these, especially in advanced stages, may so impair body resistance as to predispose to pyorrhea, there can be little doubt; that they necessarily do so, or that they express themselves in characteristic types of pyorrhea, is improbable. Even in those cases in which the defensive forces of the body are seriously impaired by the progress of the diseases mentioned, it is doubtful whether in most instances they would be sufficiently potent to actually cause pyorrhea in the absence of exciting causes. If this be true- and it seems probable guarding against the development of localized exciting causes by increased care should be sufficient to render non-operative any possible relationship which might exist.

LOCALIZED MALNUTRITION.

Largely as a result of modern habits of life, together with the end-organ nature of the circulation in the investing tissues of the teeth, they are peculiarly susceptible to trophic changes, by which is meant a loss of nutritional balance. The use of prepared foods, entailing little or no real exercise of the organs of mastication, probably has more to do with development of disease in these tissues than has the nature of the circulation, which under normal conditions is. sufficient to insure against disease. The inefficient use of the toothbrush in no small measure contributes to this condition, for as a matter of fact, it should through artificial exercise supply, in part at least, the needed stimulation in these tissues. The result is poorly nourished gums, which bleed on the slightest provocation, a fact which causes the patient to relax in his efforts at tooth-brushing, contributing thereby to the very cause which he hopes to correct.

FRAIL BONY SUPPORT.

The absence of normal exercise above referred to, together with hereditary influence, has not only resulted in poorly nourished tissues, but as might be expected under such conditions, in tissues that are subnormal in size. This will be obvious to anyone with even limited clinical experience in the treatment of these conditions, but especially impressive is it when a comparative study is made of the maxillary bones of ancient skulls with those of modern life. Such study will reveal the fact that these bones have not only undergone marked diminution in size, but in the thickness of the alveolar bone. Instead of being thick and dense at the gingival border, the alveolar bone will be found to have atrophied to a point of extreme tenuity.

This difference in thickness prevails, moreover, between individuals and between races. This is a matter of common observation, and will explain in part why it is that the incidence of pyorrhea is greater among those individuals and races with frail bony investment of their teeth. It will require no stretch of the imagination to understand why it is that teeth so supported, when subjected to adverse conditions such as prevail in poorly nourished tissues, occlusal trauma, gingival irritation, etc., more easily succumb to the destructive influence of pyorrhea than do those more favorably environed.

TRAUMATIC OCCLUSION.

Until recently few, if any, realized the relationship which exists between occlusal maladjustment of the teeth and the destructive processes which involve their supporting tissues. For a considerable time there has existed a vague notion that in some way malocclusion (using the term in the Angle sense) was an etiological factor in pyorrhea, but that pathological changes might occur in the dental investment about teeth with so-called normal occlusion, and did so frequently as a result of occlusal maladjustment, no one realized. As a matter of fact it is not a question of tooth

regularity or irregularity, but of harmony or its lack in the occlusal relations of inclined planes of opposing teeth when brought into contact. This cannot be made too plain, for it is still not clear to many that malocclusion and traumatic occlusion are quite different conditions, which may be wholly unrelated, and either may exist without the other. It is probably true, however, that other things being equal, which they rarely are, malocclusion predisposes to traumatic occlusion, and thus predisposes to pyorrhea.

Teeth may be said to be in traumatic occlusion when under the force of mastication they are driven outside of their normal limits of motion to such an extent as, under certain conditions, such as poorly nourished tissues, frail osseous support, etc., to actually induce pathological changes in the pericementum and alveolar process. There are few cases of pyorrhea in which this is not a factor to be seriously reckoned with, especially in advanced cases, where if it were not a large etiological factor, it exists as one prejudicial to recovery. Careful study of every case will be required to determine the part which abnormal motion plays in its etiology and progress. This should include observation of the occlusal relations of every tooth, number and locations of missing teeth, use of thin carbon paper, placing of the finger lightly on suspected teeth, and instructing the patient to bring the teeth into occlusion, etc.

EXCITING CAUSES.

When we come to a consideration of the exciting causes of pyorrhea we may epitomize our present knowledge by saying that anything which induces irritation of the gingiva must be regarded as a potential exciting cause, if long enough continued. The fact should never be lost sight of that pyorrhea always begins as gingival irritation, followed by solution of continuity in the floor of the subgingival space, with consequent exposure of the subjacent tissues to irritation and infection. The ease

and rapidity with which this occurs will depend upon factors which have already been considered.

MOUTH HYGIENE.

One of the prolific causes of gingival irritation is uncleanliness of the oral cavity, for the laity, in spite of the oral hygiene propaganda, have not yet learned the lesson of mouth cleanliness, at least they have not learned how to achieve it. Until they have learned this, and until there is a standardized method of toothbrushing established on correct principles that is at once simple, efficient, and stimulating, there can be no hope of successfully preventing lesions of the investing tissues of the teeth, with all their disastrous sequelæ.

FAULTY APPROXIMAL CONTACT POINTS.

Another prolific cause of gingival irritation is faulty contact points. No examination of the mouth is complete which does not include a careful study of every approximal space, and no treatment will be wholly effective which does not include correction of faulty contact points when needed. With the introduction of the cast gold inlay this has been made possible to a degree before unattainable. The shell and band crowns have been, and still are, especial offenders in this class, inducing as they do in so many instances a chronic suppurative gingivitis which will continue as long as the crown remains in contact with the gingiva. Overhanging edges of fillings, especially amalgam and guttapercha, also fall within this class. These should also be removed, and proper restorations made. Few, unless they are making a specialty of periodontia, realize how large a part faulty restorations play in gingival irritation and pyorrhea.

TREATMENT OF PYORRHEA.

In the treatment of pyorrhea an effort should always be made to determine what have been the etiological factors in the case under consideration, and as far

as possible they should be removed. Correction of occlusion, good root surgery, and the establishment and maintenance of a high order of mouth hygiene are fundamental to success in every case. Pyorrhea is a curable disease, just as tuberculosis is a curable disease, but just as patients suffering from the latter do not always recover, so patients affected with pyorrhea may not always be cured; and for the reason that in some way, which it may not be easy to explain, the conditions essential to success have not been complied with. For one thing a most exacting technique is essential. Even when this is observed complete success does not always attend one's efforts, simply because of the exceeding difficulty of meeting all the conditions. Moreover, because of a combination of circumstances which it may be difficult, if not impossible, in a given case to control, good results are not always achieved even in cases in which the prognosis seems promising.

One difficulty which attends all these cases is that to a certain extent one is dependent upon the co-operation of the patient for success. This co-operation is not always obtained, and results will be modified in consequence. The difficulty in restoring lost teeth in such a way as to prevent undue strain upon those remaining, of correcting the occlusion to insure against further trauma, and of maintaining a high order of mouth hygiene, is such that under the most favorable circumstances the results are not always all that could be desired. This being true, it is not difficult to understand why the perfunctory treatment so often given these cases is not successful, or why it is that those having failed as a result of such treatment should be pessimistic, or why they should ascribe their failures not to the inefficiency of their treatment, but to the incurable nature of the disease. Such treatment never has cured pyorrhea, and never will.

TRAUMATIC OCCLUSION.

Clinical studies of teeth in traumatic occlusion show that under the force of

mastication they are constantly being driven outside their normal limits of motion. A finger placed lightly on such a tooth will readily detect this shock when the teeth are brought into occlusion. The first change, as seen roentgenographically, is a thickening of the pericementum. This disturbance will in turn, if long enough continued, be communicated to the alveolar process, and be represented by a slight rarefaction. about the lateral walls of the root, and occasionally by resorption at the apical end, simulating a blind abscess, and often mistaken for such even by careful observers. All these changes may take place about a tooth in traumatic occlusion without solution of continuity at the gingival margins. Add to these conditions gingival irritation, and we have the three most important factors. in pyorrhea-local malnutrition, traumatic occlusion, and gingival irritation.

Treatment consists in the correction of occlusion and the establishment of normal nutrition in the investing tissues of the teeth. The correction may be achieved in most instances by judicious grinding of the occlusal planes of all teeth in traumatic occlusion. This is best done by the use of small carborundum stones, simply grinding the contact points as shown by thin carbon paper. When this is properly done, no mutilation results, the teeth are rendered more esthetic in appearance, and the patient more comfortable. Care should be exercised, however, against indiscriminate grinding.

It should be kept clearly in mind in these cases that traumatic occlusion, local malnutrition, and gingival irritation are usually associated, and that intelligent treatment requires that each be considered in its proper relation. It is possible for the teeth to be, and one frequently sees them, in traumatic occlusion, producing no pathological changes in their investing tissues, simply because these tissues happen to be well nourished. Right here is the controlling factor, and the wise clinician is he whose efforts are directed toward building up these forces of resistance. The correc

tion, therefore, of anything more than the more obvious faults of occlusion should wait upon treatment directed toward the correction of gingival irritation and local malnutrition. When this is done excessive grinding will not be necessary.

ROOT SURGERY.

The most important factor in the treatment of pyorrhea and the most difficult to achieve is good root surgery. This requires the removal not only of all calcareous deposits upon the exposed surface of the cementum, but the complete removal also of the necrotic pericementum, permitting thereby physiological contact between the vital cells of the cementum and the overlying soft tissues. Also the root must be left smooth, care being exercised not to plane through into the dentin. The instruments in most general use are of two types, curets and planes, both of various shapes and angles. It is a matter of indifference which type is employed, so long as the conditions essential to success are met. When this is done reattachment takes place, pockets are obliterated, new bone is deposited about the roots, the teeth become firm, and health is re-established in these tissues, though complete restoration to previous conditions may not occur; in advanced cases there will probably be gum recession.

I realize that it has been asserted and is still believed by many that "suppurative detachments of the peridental membrane are permanent detachments"; that since the cementum is a specialized tissue without independent circulatory system, it automatically becomes a dead. tissue when, through suppurative infections, it loses its pericemental investment. This not true. The fact that reattachment, with all that it implies, takes place in a single instance disproves any such supposition. As a matter of fact, such reattachment takes place, as a rule, in the hands of the skilful periodontist. No other result is regarded by him as a cure.

The explanation of this difference of

opinion is to be found in the fact that one group has met the conditions requisite to success, and the other has not. Reattachment will not take place about teeth on which poor root surgery has been practiced. This cannot be made. too emphatic. Inasmuch as it is not easy to discriminate between that which is skilfully done and that which is not, it is not surprising that certain observers unfamiliar with present-day requiremens should have ascribed their failures to "pus-soaked cementum," when in reality it was due to faulty technique. Reattachment can only take take place through the agency of vitally active cementoblasts, which implies vital cementum. The fact that reattachment never takes place about non-vital teeth that have become septic indicates that in some way not as yet understood the pulp is the controlling factor in the vitality. of the cementum. The absurdity, therefore, of destroying the pulps of teeth in the treatment of pyorrhea, as advocated by some, must be obvious.

POST-OPERATIVE TREATMENT OF

PYORRHEA.

The average person, even among those who make some pretension to mouth hygiene, does not give intelligent care to his mouth, and does not keep his teeth clean. This is due to ignorance, to inadequate instruments, by which are meant toothbrushes, dentifrices, silk tape, porte-polishers, etc., and to inefficiency in their use. All this must be corrected in the post-operative treatment of pyorrhea. Most cases which present for treatment would never have occurred had proper care been observed on the part of the patient and family dentist, and unless these conditions are corrected failure is bound to follow the most skilful treatment.

The importance, therefore, of intelligent home care will be obvious. Ignorance on the part of the patient as to what constitutes such care is the first difficulty to be overcome. Unfortunately, there is no unanimity of opinion among dentists on this point. There is