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incisor separator, and requested The S. S. White Dental Manufacturing Co. to stop its manufacture until I could get the time to correct its defects. I determined to abandon the idea of making it reversible, and decided to return to the old plan of my first separator. I saw that the shank could always be used on the outside of both the upper and lower incisors, if the bars of the shank were only set wide apart, so as to give access to the approximal surfaces from the front side of the teeth. This would allow the bows to be so reduced in size as to fit close to the teeth, and therefore to allow the operator to get close to his work and be in less danger of disturbing the separators by such pressure upon the bows as is almost unavoidable in working over them. Of course the larger the bows the greater the leverage when pressure is brought upon them, and consequently the greater the danger of disturbance. The reduction of the size of the bows and the setting wide apart of the bars of the shank was easily accomplished, and the result was a separator which in every respect was an improvement over the one I exhibited before the New York Odontological Society. There still remained one defect, however, which I saw must be remedied. It consisted in the obstruction caused by the presence of the screw, which still somewhat prevented free access to the approximal surfaces from the front side of the teeth, and interfered with the use of the emery-tape and sand-paper disk in finishing. I therefore remodeled the separator again, placing the screw somewhat below the points of bearing of the jaws, and turning the shank down so that it and the screw were below the line of the emery-tape when it was passed at right angles between the teeth. This gave unobstructed access to the teeth from either side. A few days' use even of this separator convinced me that it was a very marked improvement over any form of separator I had yet made,—in fact, that it was about as nearly perfect as I could ever reasonably expect a separator of this class to be made. I found that it had ample power, and that it could be applied wherever the first one could be used, and in some places where the first one could not. This separator is shown in Fig. 4. I became so impressed with the advantage of this change that I determined to remodel the whole set on this general plan.

The result is shown by Fig. 5, which represents the separator designed for the bicuspids and for the bicuspids and cuspids. It seems unnecessary to illustrate the other two of the set, as they are made on the same plan. The working of these separators in actual practice demonstrated the fact that I had made a very important improvement in them. Yet there were still some defects. Although the shank was thrown down out of the way, yet it was still sometimes an obstruction. Another fault was the unmechanical application of the force of the screw, and the uneven movement of the jaws. Opening like a pair of pliers, the outside jaws traveled more rapidly than the ones nearest the screw, and being unsupported they were less steady than the inside ones. I therefore decided to abandon these separators entirely, and to adopt and perfect a set made upon a plan on which I had constructed a separator in 1877 or 1878. This consisted in the use of screws passing through the ends of the bows on each side of the teeth to be separated. By the means of these two parallel screws I could apply the force on each side of the

Fig. 4.

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Fig. 5.

teeth where it was needed to give great steadiness, and I could dispense with the projecting shank and could somewhat reduce the size of the bows. By cutting right and left threads on opposite ends of the bars I secured rapid movement of the bows, and by making the middle of the bars square I secured the means of applying a wrench for turning them. The wrench being straight at one end and having nearly a right-angle curve at the other, it was easy to

turn the bars in any position the separator might be placed. This remodeled separator is shown in Fig. 6. As the bars are set below the line of the gum, and as the bows are turned back out of the w^ay on the sides of the teeth, the emery-tape can be not only passed between the teeth down to the gumr but it can also be considerably wrapped around the tooth toward the lingual and buccal sides so as to finish to a natural contour. With this separator the approximal surfaces can be approached as readily from one side of the tooth as from the other, and the advantage from this as well as from the unobstructed light that can be thrown upon even the most obscure parts of the approximal surfaces can be fully appreciated only by seeing the separator in operation. With teeth of narrow necks there is a tendeney to slip toward the gum when the screws are turned, but this can be overcome in a most effective manner by the use of wedges placed between the bows and the ends of the teeth. As the whole separator is made as close-fitting a,s possible, it is very easy to adjust the wedges securely. For this purpose I have used wedges of wood, cork, and lead, but I have found nothing that has proven so convenient and effective as little masses of red base-plate guttapercha, warmed and placed under the bows just as one is ready to commence the turning of the screw. It adapts itself so completely

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Fig. 6.

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to the ends of the teeth and to the bows that when it has cooled and hardened the screws can be turned as tight as desired,with no chance of displacement or danger of the jaws of the separator reaching the gum. In fact, the separator is then held so firmly that the fingers may rest upon it for support, to the greatest advantage, and with no danger of disturbance of the separator. In the performance of delicate operations this opportunity for steadying the fingers and hand is of the utmost importance.

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I have had little arrows stamped upon the separator to indicate which way the screws are to be turned in putting it on or taking it off. The separator designed on this plan for the front teeth is shown in Fig. 7. The bar is shorter and the bows are made to converge on the inside of the teeth because of the smaller circle. This separator operates as well upon the lower as upon the upper teeth. Those for the back teeth are very readily adjusted and operated, and it is with them that the great advantage of this form of separator over that of the other will be seen.

After a considerable trial in actual practice of separators made on this plan, I have become satisfied that they will easily accomplish all that can be expected of any device for the immediate separation of the teeth. My first form of separator, having but one screw to manage, is a trifle more quickly applied and easily operated, but in no other way whatever have I found it to possess any advantage.

The double screws work easily and give no trouble whatever if only a little care is taken to turn them about equally.

It may be well to say here that care should always be taken in using the separator upon the superior central incisors, because of the possibility, with young patients more particularly, of opening the suture of the superior maxilla. This has never occurred with me, nor have I ever heard of its occurrence with others, but it is well to bear in mind the fact that it might occur if the screws were used injudiciously.

Besides the gaining of space for the performance of operations on the approximal surfaces of the teeth, there is another most important use to which either of the two classes of separators which I have described can be put. I refer to their use as matrix-holders.

Nearly a year ago my associate, Dr. Wm, Woodward, presented me with a set of steel matrices, designed by his brother, Dr. J. A. Woodward, who has since illustrated and described them in the Dental Cosmos for June, 1885. I have found them almost invaluable. In discussing their merits with Dr. Darby, who had also found them of great service, he suggested to me that they would be held very securely in position by the use of my separator. I saw at once the value of this suggestion, for I had not always been quite successful in securing them in position by Dr. Woodward's method of wedging. Upon trial I found this plan to work admirably, but there were still some little defects. Being made of steel and tempered, they were not as adjustable as I desired, and they were not of quite the right shape to be always well held by the separators. I therefore substituted brass, and changed their shape to that shown in Fig. 8. As will be seen, they are long enough to wrap well around the tooth, and the shapes are such as to fit them well to the festoon of the gum and to give the separators a firm hold upon them. This will be seen by a careful examination of Fig. 1. I use them in the following manner: I adjust the dam and apply the separators, turning the screws until the teeth are sufficiently separated to allow the matrix (which is now flat) to be slipped between the teeth. I then remove the separator entirely, and bend the matrix closely around the tooth. This being done, I replace the separator, putting the jaws over the matrix, and then tighten the screw as much as needed. After the filling is completed I remove the separator and straighten out the ends of the matrix, and then reapply the separator on the tooth alone. By turning the screw the matrix is loosened and removed, and then the filling is finished with no danger of the slightest loss of contour. The malleability of the brass matrix may be taken advantage of in securing a full contour, for wherever it is desirable to swell the filling it is only necessary there to use the lead or the automatic mallets. Under the application of such force the matrix yields slowly, and the filling can be bulged even beyond the natural contour, if desired. This same malleability of the matrix can also be made to help in securing perfect margins.

It is undeniable that there is danger in the use of a matrix of any kind, for in packing along the margins of the cavity it is only by the very greatest care that a perfect adaptation of the gold can be secured. In fact, it may be doubtful if a perfect adaptation is often made if the matrix fits the tooth absolutely and unyieldingly, and I have found a real advantage in driving the gold and the matrix, by mallet force, a little beyond the edge of the cavity, when this can be done,—as it can be if the matrix is thin.

Large approximal operations, where restorations are required, can be very expeditiously performed by this combination of the adjustable matrix and the separator. I have found the velvet cylinders recently brought out by The S. S. White Dental Manufacturing Co. to be a most beautiful preparation of gold for all operations where matrices are employed.

In large cavities which extend under the gum these matrices, as well as those of Dr. Woodward, are of great service in depressing the gum and carrying the rubber-dam above the margins of the cavity.

I have occasionally made use of the matrix in another operation which I have sometimes performed with considerable satisfaction. It is that of cutting through from the buccal or the lingual side, instead of down from the grinding surface, when small cavities near the gum on the approximal surfaces of biscuspids and molars are to be filled. It is not an operation to be performed, however, if decay approaches near to the grinding surface, for frail structure here is liable to be broken away by the force of mastication, even though the arch of enamel is supported by a solid filling. In the performance of such an operation, the part of the cavity most difficult to fill accurately is that along the lingual border, when the cavity is opened into from the buccal side, or along the buccal border when approached from the lingual side. In such cases I have used a thinedged brass matrix, held in place by the separator, as shown in Fig. 2.

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