A New and Simple Method of Constructing a Special Seamless Crown, Dr. Some of the Professional Duties of the Dentist, D. N. Swift, '94, The Normal Shedding of the Temporary Teeth, W. H. Van Deman, Some Suggestions as to the Relation of the Teeth to Empyema of the Max- There has been no recent announcement made that is of more importance to the Dental Profession in the west, than that giving notice of the opening of our branch house in Chicago, the wisdom of which has already been proven. The Profession come to us feeling confident from their long experience, that they can depend upon getting reliable goods at prices consistent with good workmanship. Inferior products are never cheap at any price. It is always sound economy to use the best of everything, which is now placed practically at your door. We have always given careful attention. to every detail of manufacture, recognizing the fact, that the perfection of our ideal-whether it be in an artificial tooth, a dental instrument or supplies, is essential to the perfection of the professional ideal. GIDEON SIBLEY. MAIN OFFICE AND FACTORY: 1214-20 FILBERT STREET, PHILADELPHIA. 205 STATE STREET, CHICAGO, ILL. Published Under the Auspices of the Dental Society of the University of Michigan. VOL. III. DECEMBER 20, 1893. NO. 1. Published bi-monthly throughout the college year, the first number appearing in December. The subscription price is $1.00 per year. All communications should be addressed to L. E. Coonradt, 32 E. Liberty street, Ann Arbor, Mich. Entered at the Postoffice at Ann Arbor as second class matter. A NEW AND SIMPLE METHOD OF CONSTRUCTING A SPECIAL SEAMLESS CROWN. DR. W. H. DORRANCE. This method is applicable in all cases where it is desired to fit a molar or bicuspid perfectly for the support of a piece of socalled bridge-work. If the occlusion of the opposing teeth will not permit the requisite thickness of gold to intervene, grind the tooth to be covered (or its occluding fellow, or both, if best). With a Take an impression in plaster and fill it in such a manner that it may extend some length in the direction of the root. sharp point scratch lightly into the tooth following the gum linethis is to aid, if needed, in the future trimming of the crown. Trim away the model in the direction of the root of the tooth to a somewhat cylindrical form but in section having the shape of the tooth at the neck. Wrap this cylinder about-carrying the wrapping up as high on to the grinding surface of the tooth as is easily convenient-with tin rolled to the thickness of gold to be used, say No. 28, Brown & Sharp's gauge, taking care to make a smooth butt joint, and to carefully burnish the tin to the surface of the model by wrapping with fine wire or thread about the end opposite the crown. Press the still uncovered portion of the crown of the model into moldine (clay mixed with glycerine) and cast a button of fusible alloy into the impression thus formed. Oil this button and strike it into lead, and with these dies lightly swege from a disk of the same tin a cap which, when trimmed and fastened to the model with a very little wax completes the covering of model. Take an impression of this tin-covered model, either by dipping in plaster to the line of the neck of the tooth, or should the bulge of the crown prevent dipping, an impression must be taken in halves, which when filled will give a model of the tooth which · is larger than the natural tooth by the thickness of the gold crown yet to be made, but similar in every other respect. Trim this model as the first, and when nearly or quite dry. dip to the neck line in melted fusible alloy, withdrawing the model just as the alloy sets. A cheap and fair alloy for this purpose is made of tin eight parts, lead one part and bismuth one part, all by weight, melted together in the order named, and when well mixed, poured in buttons on a cold slab. This alloy melts at about 360° F., and is strong and hard, but does not cast quite sharply. A better alloy consists of lead, five parts, tin, three parts, and bismuth, two parts. This melts at about 212° F., and casts sharply. A convenient way of using it for the present purpose is to cast in common brass ferules, using one 5% in. in diameter for bicuspids, and one 3/4 in. in diameter for molars. Place a suitable ferule on a smooth, cold surface, like a flatiron, a large hammer, an anvil, or a piece of steel plate, melt the alloy and pour into the ferule, and at once dip the model as deep as the neck of the tooth only, withdrawing the model carefully just as the alloy begins to set. After dipping and removing the model, and the mold is cooled, it should be trimmed with a sharp knife about the border to remove the slight undercut, and oiled. It is than ready to receive. the little cup of gold formed by the Morrison outfit out of 22k. gold. The cup should be of such size as to slip into the mold, though it may sometimes require flatting a little on two or more sides with a light hammer, after which it must be about two-thirds filled with oiled shot of the size called "dust," and driven to shape in the molds with the punch that last drove the cup through the die plate. The now fully formed crown may be worked out of the mold, or if it sticks too much by reason of its shape, it may be carefully melted out, and when trimmed this crown will be found to exactly fit the natural crown for which it was formed. A mold constructed of the above alloy by either dipping a natural tooth (the surface of which has been lightly oiled), or a model of a natural tooth, will be found to be much more satisfactory for forming a seamless crown than the plate which is a part of the Morrison outfit, and will stand well for forming several crowns. When worn out or dull, the molds may be remelted and redipped indefinitely, care being taken to avoid overheating. With a variety of extracted teeth, typical molar and bicuspids, whether sound or made so in shape at least, by filling with cement, or with models of such teeth as we desire to reproduce in shape in a seamless crown, a mold can be made and a crown formed in five minutes, and the maker is not limited to a few shapes. SOME OF THE PROFESSIONAL DUTIES OF THE D. N. SWIFT, '94. Read before the Dental Society December 18, 1893. I have no doubt that most of us imagine we have a perfect right so we quite understand the professional duties which will devolve upon us, when, with feelings of intense pride, and exuberance of youthful spirits, we receive that most precious of all documents our diploma-and step out through the door which it opens for us-into the vast field that lies in all its inviting grandeur and beauty before us. It is, no doubt, a wise provision of nature, that much which lies before us is hidden from our view, and that our high aspirations, and abundance of hope, enable us to see only the sunshine, and starlight, while the clouds and storms are retired from our view. But it will be well for us to prepare for strife, because we will undoubtedly find imposed upon us onerous duties; duties which will require plenty of moral courage to perform; and which if neglected will cause our overthrow professionally. But I would not speak of our coming responsibilities, from a pessimistic standpoint, but rather that they may be cheerfully encountered and honorably overcome. "No excellence without labor," is a trite saying, but I am sure it applies to Dentistry as well as to any other profession or calling and if we could attain to high standard of excellence |