It

in phagocyting the bacteria growing in these pockets, and there is not the slightest doubt that this wall of leucocytes destroys an enormous amount of bacteria found growing in these crevices. In addition to the phagocyting of this bacterial mass, the wall of leucocytes acts also as a limiting factor in the spread of bacteria from these foci into the general circulation. However, we all must realize that the leucocytes tho endowed with amaeboid movement cannot and do not readily cross the crevice to the root itself and the bacterial examination of the material of the root itself shows that it is always heavily loaded with growing organisms. naturally follows therefore that on account of the rather limited movement of the leucocytes that they only do efficient work in the destruction of bacteria, as bacteria are brought in close contact with them and the tooth's root surface must of necessity receive little or no help from them. Here for a moment study pictures of tooth root surfaces as they appear when the fibre ends are digested out of the tooth's root surface by appropriate media. (Show lantern slides of tooth root surface.) Figs. 10 and 11.) You will note in the study of this second slide which is under a quarter inch subjective that it presents three distinct characters of tissue, namely, this rough surface that has been untouched by instruments which appears on the left. The center of this field shows a great many lacunae and the right side of this same field shows a plane surface in which there are a comparatively few openings. This particular slide was especially prepared to contrast these three conditions.

The author next invites your attention to this picture which shows distinctly the dentine of the tooth structure and outside or overlying this dentine field, you will note the inner layer of the cementum in which you see a great number of lacunae. (Figs. 11 and 12.)

I

able breadth of tissue in which there are very few or no cementoblasts. wish you to give particular thought to the morphology and histology of this tissue, as the writer believes it to be infinitely important in the treatment of pyorrhea pockets, because it affords the reason for planing root surfaces and also shows just the depth one dare cut to advantage. Following the general rules of surgery with infected pockets of this type the natural thing would be to curette the ulcerating tissue. As far as the necrotic remains of the soft tissues surrounding the tooth's root is concerned, that is surgically easily accomplished. As for the alveolar process itself,

Shows lacunae from center of field in Fig. 11.

of material, which is stinking and necrotic, to be removed from these pockets is resident on the root surface itself

sues. In the first place, the amount of dead necrotic material upon the root surface, while considerable in area, is very shallow in depth and when instruments of any character, planes, files, or scalers are thrust into these pockets, the operator should have in mind the structure of the tissue upon which he operates for the simple reason that if in removing the dead necrotic root surface, the operator carelessly cuts down a sufficient depth to open the lacunae of the cementum, that tho his initial result may point toward health in the improved appearance of the gums and surrounding tissues yet in the end these root surfaces re-infect because the

Calculus on root surface. How futile to expect medicines of any kind to benefit a tooth of deposits of this character.

into the cementum will always hold bacteria. The writer believes this fact explains why certain operators who handle the teeth they treat roughly have many recurrences of infection while others who have greater skill and patience have comparatively few recurrences of infection. The moment the dead root surface has been carefully removed, the inpour of new leucocytes is exceedingly rapid because the blood vessels which supplied the bone and peridental membrane have not been entirely destroyed, tho their ends have been blocked by an obliterating endarteritis, which is the specific lesion of pyorrhoeal infection. The operative interference necessary to

clear the root surface breaks down these endarterial structures and permits of a great outpour of blood into the pyorrhea pocket itself. This bleeding is an excellent thing as it tends to carry out of the pocket infinite numbers of bacteria and also introduces into the pocket fresh arterial blood, which is nature's provisional filler of every wound and a better antiseptic for such wounds than any drug which we could place in them. To briefly describe the character of this type of surgery may be of some interest

Fig. 13 B.

Calculus on the root surface.

in this connection. It is most easily accomplished with the planes of self-limiting cutting depth. The operator should begin at the neck of the tooth and with short strokes remove the dead material, each stroke going a trifle farther into the pocket until he finally has planed off all the objectionable material to be removed. As the surface cannot be seen the operator must depend on his sense of touch. On root surfaces where there is no deposit, the sharp plane encounters first the dead peridental membrane which evokes a sensation which the author might liken to touching silk velvet, a sort of fleshy feeling. A few strokes with the sharp plane removes this velvety material and brings the plane in

contact with the uneven bony surface of the root itself. This produces a sensation entirely different than that produced by the touching of the dead peridental membrane and cannot be well described in words. If, however, the root has upon it serumal calculus, the sensation conveyed to the operator by the plane bit thru the medium of the handle of his instrument and the plane bit, might be comparable to the application of a steel edge to a concrete or stony surface. Upon removal of this stony, gritty material in the one case, or the removal of the velvety dead remains of the peridental membrane in the other, the plane bit rapidly renders the surface smooth and conveys to the operator a sensation comparable to that evoked by rubbing a steel burnisher over polished ivory. In contrast to the sensation evoked by touching dead peridental membrane or calcific deposit, the sensation is so markedly different that after it has once been experienced, the operator can definitely know that he has removed all that should be removed from the root surface. If now the operator, heedless of the fact that he has reached the hard layer, continued to cut with sharp instruments for a few seconds on this smooth ivory-like surface, which he has been able to produce by the removal of dead peridental membrane or calculus, the operator will soon find that the instrument will chatter and the sensation will be as vitally different to him as the sensation evoked by bringing a sharp curette over the bony plate of the alveolar process as compared to the sensation evoked by the same curette when used in the spongiosum of the loose areolar bone inside of the bony plate. It naturally follows that the fewer lacunae opened, the less subsequent re-infection. As the operator approaches the bottom of the pocket he will encounter granulation tissue. This granulation tissue is a mass of leucocytes which interposes between the bottom of the pocket and

living tissue beyond and serves to protect the living tissue beyond from further incursions of bacteria and also surrounds the obliterated ends of the vessels which fed the tissue. It is an advantage to press the plane bit into this mass of leucocytes in order that every bit of diseased root surface may be removed and also to break up the granulating wall and open the obliterated ends of the vessels in this locality. The action of the plane bit will naturally withdraw from the pocket most of the planed

Fig. 14 A.

experiments in this direction must ever be remembered. He was able to remove portions of long bones in dogs and interposed between the cut ends of these bones small glass tubes which glass tubes filled up with new bone in from four to six weeks, the outpour coming from the cancellus bone cells of the ends of long bone and not from the periosteum. Accepting the fact that new bone (Figures 15 A and 15 B) comes from preexisting bone cells, can we do (Fig. 16) anything which will tend to repair the

Fig. 14 B.

off material. If the operator is in doubt as to whether the pocket is free from loose material, it is wise to syringe the pocket with Ringer's solution or normal salt solution.

Assuming always that the diagnosis has been properly made and the advisability for treatment of any given case determined and that the work has gone forward to the removal of the diseased root surface, the next thought which confronts us is the possible regeneration of bony process to compensate for that which has been lost. The regeneration of bone of course precedes from living bone. This has been well proven by the work of Macewen (*1) of Glasgow, (Figures 14 A and 14 B) whose classical

*1-Macewen-"The Growth of Bone."

Transplanted sections showing perfect union.

loss of bone already suffered? The writer believes to a limited extent that we can, by simply following the laws of general surgery in relation to bone growth. Therefore, our need is freshly opened bone cells, absence of general infection, absence of pressure, and rest. Presuming the pyorrhea pocket and root surface to be as surgically clean as they can be gotten, our next step is to reach into the process with a fine sharp instrument and lightly stir or roughen up the process edge. This stimulates the bone cells to an outpour of callus. If the pocket be filled with sterile blood clot, the new bone cells pour out and in some instances actually pile up against the root surfaces never in great amount because the pressure of surrounding tissue limits the amount of outpour, be