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Les diagrammes suivants illustrent la mAthode. errata d to e pelure, ;on d n 1 2 3 32X 1 2 i 3 4 5 6 I t &- I ^ I' I 1 II I ^ Vx--.i-. -^ Porcelain Dental Art. -@- Jhe Jsjew ^roQess OF RESTORING DECAYED AND DEFECTIVE TEETH TO THEIR ORIGINAL APPEARANCE, IN SHAPE, SIZE AND COLOR. BY, C/H. LAND. DETROIT, MICH. : O. S. OULLtY, BORNMAN * CO., li-lS LARMBD STREET CABT. 181)0. * I*. ^ <-> y^i Copyrighted 1888, by Charles H. Land. I I / I in n r\ r i , e r\ INTRODUCTION. Porcelain Dental Art. •"t^HE practical application of porcelain to operative and mechan- ical dentistry is not possible without its necessary adjunct, a thoroughly reliable pas furnace; and this must bo so arranged that all operations are reduced to the minimum cost of the material con- sumed and lalxjr expended, and with the least fatigue both to the operator and his patient. Twenty years of experience in the working of continuous gum work, sectional block and crown work, and three years constant and daily exi)erience in inserting of porcelain fillings, etc., has demon- strated and brought out so many minor details that in order to com- prehend them properly, nothing but actual practice will suffice to furnish anything like a correct idea of the great value of proper facilities; and, while it will be the aim of the author to simplify the instructions, the fact still remains that no matter how simple the art, there are always some features that need actual work. A very slight oversight on the part of the most careful observer may cost hundreds of dollars, where a little actual contact would save it all. A close inspection of any art reveals truths that can not be comprehended at a distance; therefore, to all those who will become interested, a week spent in our laboratory will be of the greater vnlue; however, as there are a large number in the profession who xi? d it very difficult to get away from home, we have decided to do all that is possible by giving a series of illustrations and simple directions, and hope by this means to establish enough facta to enable them to make a beginning. Respectfully, C. H. LAND. DR. C. H. LANDS COMPOVNto GAS OR GASOLINE FURNACE PATENTED JANUARY 3d, 1888. VO. I. NACE Dr. C. I. Lail's CoipoDDd Gas or Gasolioe Famace. Size No. 1, eHpocinlly mlapto*! for (•ontimionH gnin work, nil kinds of imiffle work, crucible work, blow |)i|.« work, f(>rj,'iiijr iind brazing. It is the inoHt complete fiunnce over (loviwcd for tht< choiu ist, HHHHyor, jeweler, dentist and uietallnrgiHt. The range of work that can be accomplished with it is practically without limit, Iron, brass and steel castings weighing from 2 to 12 pounds can be made in from 7 to 80 minutes. A mutlle 8 inches long, 3J inches wide, 2.J inches high inside measurement, can be heated to ov«*r 8240^ F. in 25 minutes, sullicient to melt wrought iron. Fig. 1 rejnesents the furnace closed and ready for muflle work. A A is iron pipe, ca[)able of both a sliding and swinging motion. (See L Fig. 2), to which the door or plug is securely attached. There is a small hole in the door, covered with a piece of mica, through which all operations can be seen. Observe that the iron pipe is connected to rubber tubing B, and with pipe having an air cock C, which regulates the (juantity of air passing into the mouth of the muffle. It will also be noticed that the pipe passes over the two holes D D, thus by the escaping flame the pipe is heated to redness and provides a superheated air before reaching the muffle; this column of air forced into the muffle keeps up a counter pressure within, so much greater than the press- ure produced by the blast within the lire chamber, that all foul gases are prevented from entering the muffle even though it is cracked; thus the most delicate porcelain can bo baked without the least danger of so-called gasing. Also it will be seen that by coimecting the rubber pipe with retorts or gasometers any desired vapor or gas could be forced into the muffle, making the furnace invaluable for scientific experiments. Fig. 2 illustrates the furnace thrown open, being swung on hinges at the back, exposing the muffle E. The groove P P is packed with asbestos fibre, so that when the sections are brought together the furnace will be perfectly air and gas tight. The hooks F F are to hold the upper section secure to the lower. The gas and air con- nections are so arranged that the ordinary blow-pipe can be attached as shown at G. When the muffle E is removed, it exposes two Imrn- ers and a tire-brick surface made to fit the various appliances for crucible, ladle and blow-pipe work. One or both burners can be operated in conjunction with the blow-pipe G. The air-cock R is to provide a means for shutting off the air supply from either burner when required. H is the gas supply, K air-pipe connecting with the ■■,A.".W!Ji4i )/»i" bellows. Size of rauttle, iusitle meaHurement, 8 inches long, 2J inches high, 8^ inches wide. With gasoline gas porcelain teeth can be enameled in from 10 to 15 minutes; ordinary city gas in from 15 to 25 minutes, according to quality. In 30 minutes a heat sufficient to destroy the muffle can be producod, which indicates a temperature of over 3240" F., much higher than is ever m'edod for all kinds of work, except the fusing of platinum. Three-eighths-inch gas pipe will supply sufficient gas, and can be worked with ordinary foot bel- lows. . THE CRO^A/'N FURNACE Is about one-fourth the size of No. 1-muffle 3 inchos long, H inches in diameter. It is a fac simile of No. 1, having blow-pipe and crucible attachment, and is especially adapted for enamel fill- ings, crown and sectional block work; is much easier to operate than No. 1, and does the work more rai)idly. p^ ■5{? ches long, 2 J (lain teeth can jas in from 15 heat Hufficient 1 a temperature ir all kinds of -inch gas pipe inary foot bel- CE achps long, 1\ ving blow- pipe or enamel fiU- to operate than Reprinted from " Itemn of Interest, " October, IHS({. ARE HYDRO-CARBON OR QAS FURNACES A SUCCESS ? Hv Dh. C. ... LAND, Dctroit, Mich. For those who are not familiar with the nature of hydrocar- bons, the philosophy of their coinbustiori. etc., gas furnaces are not satisfactory; but the mastery of a few definite facts will make the whido subject plain, and the process easy. During the past year it has Iwen my pleasure to bake over one hundred sets of continuous gum work, also sections of block work, porcelain, etc. This I have done with no more trouble than to turn on the desired (|nantity of gas and air and wait till the operation of baking was completed. Starting from a cold muffle it requires but fifteen minutes for the first biscuit, ten minutes for the second, and fifteen minutes to enamel, and where two furnaces are employed a slab of sectional block teeth can be enameled every five minutes, in the moat perfect manner, with unerring precision. Some gas furnaces have been a failure principally on account of their liability to gas the teeth. The accompanying illustration will make the philosophy of combustion more clear, and give the reasons why teeth are injured. A repre- sents the burner ; B B B fire-brick lining ; C C C combustion cham- 8 ber; D interior of muffle. The arrows indicate the direction of the blast. The space in the combustion chamber between the lines E E is where carbon monoxid (co) is formed, — a gas containing one equivalent less of oxygen than carbon dioxid — simply an imperfect state of combustion. It is this gas that injures the body and the enamel. By reference to the illustration it will be seen that the l' Me arrows are made to appear passing through the pores of the muffle, and as the -iirection of the blast from the burner A is directly against the bottom of the muffle, with a pressure of one pound to the square inch, a portion of the carbon monoxid (c o) is extremely liable to be forced through its pores, and will be taken up with the body during th3 first and second biscuiting, here to remain until the enameling process; and as this takes a much higher degree of heat, it causes the gas to be eliminated, as shown in the numerous small bubbles on the surface. The space between the lines E E and within the com- bustion chamber C C C, should be known as the first ctage of com- bustion, where a certain portion of carbon monoxid (c o) is always present, and the space between the lines G and E, within the cham- ber C, should be known as the second stage of combustion. In the first stage of combustion one equivalent of oxygen from the atmos- phere unites with the hydro-cai'bon to form carbon monoxid (c o) ; in the second stage, two unite to form carbon dioxid (c Og ), or car- bonic acid. In my first experiments in baking porcelain with hydro- carbon fuels, nitrogen was injected into the muffle as a protection to the teeth, and proved highly successful. Further investigation has shown that porcelain can be baked satisfactorily by using a little air. Fig. 1 represents my new furnace closed and ready for muffle work. In Fig. 2, see exposed position of muffle. A A, Fig. 1, is iron pipe capable of both a sliding and a swinging motion (see L, Fig. 2) to which the door or plug is securely attached. Rubber tubing B, Fig. 1, connects with air supply at cock C. This regulates the quantity of air passing into ihe muffle. In the illustration you have seen that the monoxid of carbon (c o) is extremely liable to penetrate the muf- fle. We will assume that a small portion has entered the muffle; then what could be more reasonable than to force in a small quantity of air rx) unite with (co) to form (co,). To prove the theory cor- rect, the entire upper portion of the muffle can be perforated with holes; this will allow the products of combustion (co ) to pour in it a constant stream,and yet a set of teeth can be baked successfully without any danger of gasing, though, owing to the one equivalent of carbon a slight discoloration of the enamel will be observed. By perforating the muffle with three 4 inch holes on the upper portion of the rear irection of the the lines E E lontaining oue an imperfect body and the 1 that the lUUe of the muflle, irectl^ against I to the square (ly liable to be e body during ;he enameling keat, it causes lall bubbles on ithin the corn- stage of com- c o) is always liu the cham- stion. In the om the atmos- aonoxid (c o) ; c Og), or ear- in with hydro - a protection to estigation has ing a little air. ir muffle work. 1, is iron pipe » L, Fig. 2) to tubing B, Fig. IS the quantity have seen that jtrate the muf - Bd the muffle; small quantity le theory cor- lerforated with I to pour in it a Bsfully without ent of carbon a By perforating )n of the rear g end it wUl give vent to foul gases, and when a current of air is passed in at the front the tendency would be to paHs out at the roar. As this current of air consists of nitrogen and oxygen, the latter would unite with any (c o) that might be present, leaving an excess of the former. Nitrogen not uniting radically with anything, serves as a protection to substances placed within the muffle. It has been customary to perforate the end of the muffle in coal or coke furnaces, and as the natural draft would draw a sufficient quantity of air through the muffle, any monoxid of carbon nresent would be eliminated, consequently teeth were not gased' unless placed in a cracked muffle. In all hydro-carbon furnaces it is necessary to use a blast to secure the required amount of heat, and the pressure must be at least one pound to the square inch ; this is to force the proper amount of oxygen into the combustion chamber. Perfect combustion wiU not take place in natural-draft gas furnaces, because a sufficient quantity of air cannot be drawn into the combustion chamber without the use of a positive blast ; it therefore becomes necessary to force both the air and the gas under pressure into the combustion chamber, the higher the pressure the greater the heat. My office is located in a building where steam power is available ; from this I secure an air supply, conducted by means of gas pipes into my laboratory, so that by simply turning on a supply of gas and air, teeth are baked with much less trouble than vulcanizing. Where it is customary to bake every day a motive power is the most desirable, but where only an occasional set of teeth is required, the ordinary foot beUows answers better. But fifteen minutes of pumping is sufficient for each bake, and with a little assistance the work is comparatively easy. The Use of GasoKne.— During the past year I have been using 74 gasoline with as perfect results as any other hydro-carbon ; and with the ordinary foot bellows, as manufactured by the Buffalo Dental Manufacturing Co., I can bake a set of continuous gum-work in fifteen minutes, starting from a cold muffle. All kinds of crucible work and soldering vrith the blow-pipe, can be done equally weU as with city gas. One gallon of gasoline, costing 15 cents, will bake a set of teeth. Therefore, dentists living in localities where there is no gas can secure equal advantages in the use of 74 gasoline. City gas, at $2.50 per thousand feet, will cost about the same. V y i 10 DIRECTIONS FOR SETTING UP THE PURNAOE. Adjust the bracket so that the top will be three feet from the floor, orthe8ameif placed on the bench. The hole shouldbe elevenincheB in diameter each way, and seven inches from the wall. The bench should be twenty-four inches in extent from the wall, and twenty-two inches wide. The groove P P should be packed with asbestc^i fibre. Roll the fibre into a loose rope about half an inch in diameter. This is intended to secure an air-tight joint between the upper and lower sections of the furnace. ADJUSTING THE MUFFLE. The groove across the front end of the base of the furnace is intended for asbestos packing, and as a guide to set the muffle in its proper place. The raised or thick part of the front of the muffle should come exactly even with the groove, or there should be a space oi three eighths of an inch wide between and around the mufflo vvithin the combustion chamber. If the muffle is too close to the rear end of the combustion chamber, the Uability to gas the teeth is increased, and the necessary degree of heat will be too slow in developing. Also, it will be more difficult to light the furnace. Combustion will be imperfect. i ADJUSTING THE BURNERS. Previous to putting the burners in place, the smaU piece of woven wire is pushed up into tiie tubes. Aebestos fibre is then wound around the head of tiie burners, and serves as an air-tight packing, then tiiey are retained by means of thumb screws. After the screws are turned so as to secure tiie burners, a little additional asbestos fibre is packed between the tubes and the burners ; tiiis makes the joint perfectly air-tight. To the right side of tiie furnace the letters M M mark the point where rubber tubes conduct the air supply to tiie burners ; R R is stop cook to regulate tiie quantity of air passing into the burners ; O O, pipes to the left that convey the gas to the burners. -f^ ^t^r TSsr. QRNAOE. from the floor, I eleven inches . The bench id twenty-two asbestc;) fibre, iameter. This per and lower 11 LIGHTING THE FURNACE. A little trouble is sometimes experienced in lighting the furnace. The flame will start beneath the furnace, in the lower part of the tubes. When this takes place, if continued, it will melt the wire screen at the head of the burner. To prevent this, a steady current of air, uniform in pressure, will avoid the danger of starting the flame below the combustion chamber. When it does take place, the gas should be shut off at once, and try to light it again. the furnace is le muifle in its b of the muffle luld be a space and the muffo oo close to the [as the teeth is be too slow in it the furnace. small piece of »s fibre is then as an air-tight screws. After little additional e burners ; this 9 of the furnace conduct the air the quantity of that convey the THE USE OF GASOLINE. A convenient way in which to use gasoline, is to pass a current of city gas through the generator. This gives a rich hydro- carbon, and is less liable to gas the teeth than when city gas is used. When gasoline is used alone, a current of air from the bellows must be passed through the generator; this carries the vapor into the com- bustion chamber, mixed with the proper quantity of air. The gen- erator should not be more than half filled with gasoline; if filled too full the fluid will be forced up the pipe and is liable to overflow and ignite outside the furnace. After passing a current of air through the generator tot some time, a heavy residue will accumulate; this should be thrown out, as it will not vaporize. I I 1 I Fig. 1 in the engraving B indicates the manner of making the connections for the use of gasoline; here the large size furnace is phown standing on its end, so that all the connections may be better understood. Fig. 2 illustrates the smaller size or" crown furnace. This is especially adapted to do the smaller kinds of work, such as fillings, sectional block work, and the various kinds of crowns, pivot teeth, etc. The operating of this furnace is very easy and simple; in from five to ten minutes porcelain can be fused in the most complete man- ner, and this with comparative ease, using the ordinary foot bellows, as seen in the engraving, and to those who do not care to do contin- uous gum- work it will be by far the most desirable, and entirely satisfactory. Size of muffle, one and a quarter inches in diameter and six inches long. I ' a , : I TO REPAIR ORAOKS IN THE MUFFLE. Take pure asbestos fibre in an old muffle, heat it up to about the same heat as it would take to melt gold, say 2200° F., then mix, grind to a powder in a moi-tar, and mix with two-thirds more of powdered fire clay, make into a paste by the addition of water, care- fully work this paste into the cracks in the muffle and let it dry by a gradual heat. 1 J.I i,tei%.,U*^ -- ^ ' f making the ze furnace is nay be better i lace. This is ich as fillings, 3, pivot teeth, nple; in from jomplete man- f foot bellows, ) to do contin- and entirely I in diameter PLB. k up to about ' F., then mix, airds more of of water, care- let it dry by a COUNTER-BLAST AND REGULATOR. The importance of this valuable adjunct to Dr. Land's furnace will become the more appreciated as the operator is made familiar with the simple facts relating to the philosophy of combustion, and to those who will carefully investigate, a very rich and interesting field is presented, not only for the dentist but also the chemist, the assayer, the metallurgist, and the scientist. However, in this instance I must confine my efforts to dentistry. The illustration. Fig. A 1, is a regulator that is attached to the counter-blast This device is to definitely control the quantity of air passing into the muffle. The object of forcing a current of air into the muffle is two-fold, in one instance the oxygen will unite with any free carbon that might be present, and the counter pressure produced from the blower would force any foul gases out, even though the muffle becomes cracked, which is liable to take place eventually in every muffle. In baking continuous gum-work, the indicator is set at a num- u her on tho dial, ho that in tho beginning of the operation a very large volume of air enters the muffle, and is continued until the tempera- ture is almost to a white heat, the amount of air is then gradually reduced by Uirning the indicator back to the smaller numbers d, 4, D etc Since the materials that are incorporated in the bodies and enamels are formed largely of oxygen, in combination with other elements, and realizing the great affinity that carbon has for oxygen, it will become apparent that the so-called gasing of porcelain is due directly to the deoxidizing properties of the carbon, which penetrates through the muffle in the shape of the fixed gas monoxide of carbon; or it may be some unconsumed hydro-carbon; in either case, the passage of a current of air into the muffle would convert any excess of either into dioxide of carbon, and thus prevent any detrimental effects. The arrangement of parts provides a sure preventive of any injurious effects, even though the muffle should break down during the baking process. As there is no available substance that can take the place of well prepared fire clay, muffles will continue to be made of it; therefore, this new device is likely to become a permanent and necessary part of a thoroughly reliable gas furnace. BAKING CONTINUOUS GUM-WORK. When the first lot of body is spread over the plate, the piece can be placed in the cold muffle, the door closed, and thence counter-blast set at Fig. 7, 8 or 9. This keeps a full and steady supply of air in the muffle until the heat has increased to a bright red appearance, or almost a white heat can be attained. Then it will be time to reduce the quantity of air by shifting the indicator back to a number where just a small amount of air is passing into the muffle The operation is then continued until the body is fused to a partial glaze. This completes the first biscuit. The piece is then removed, and as quick as possible placed in a cold muffle, the air excluded by closing the mouth with a suitable door or stopper. Here it is allowed to gi-adually cool, which requires about twenty minutes. It is then ready for the second application of body. This consi^s simply in filling up the cracks due to the shrinkage of the body when fused in the first instance. It should not occur in the second operation. Any defects of the first manipulation can be corrected by adding additional body, all cracks being filled and a t^^^^o^* «* body spread over tiie entire first biscuit. The piece will be ready for tiie second fusion, which should be conducted m the same ^-4. 16 n a very large the tempera- ben gradually mbers, 3, 4, 5, he bodies and )n with other as for oxygen, )rcelain is due lich penetrates dde of carbon; her case, the rert any excess ly detrimental jventive of any k down during le that can take jontinue to be ne a permanent ice. plate, the piece d, and then the full and steady ased to a bright ained. Then it ng the indicator passing into the body is fused to he piece is then d muffle, the air )r stopper. Here twenty minutes. f. This consists cage of the body 5ur in the second can be corrected nd a thin coat of ace will be ready sted in the same manner as the first. It will then be ready for the enamel, and passed through the muffle following the same directiona While it may be possible to fuse porcelain in other f;a9 furnaces, without the use of a counter-blast, and occasionally produce a fairly good piece of work, it will eyentually be demonstrated that the current of air will always be a necessary element in order to obtain that rich color so desirable to imitate the natural gum, and to guarantee toughness to the porcelain, and not be made brittle from the action of even the smallest portion of carbon. IMPORTANT. In the use of Dr. Land's Continuous Gum Furnace it must not be supposed that the mere baking of porcelain dentures is its greatest value, for where one opportunity of this kind is needed five hundred other opportunities will be presented for various other applications of dental porcelain. In Dr. Land's practice it has been thoroughly demonstrated that the time has arrived when it is entirely feasible to mould sections of porcelain into the exact form of the cavity of a tooth, and in every case secure an adaptation of about the two thousandth part of an inch. These results are possible in every form of the cavities in decayed t«eth, starting from the most minute cavity until the entire tooth becomes involved, and with the various shades of body each tooth is imitated in shade, shape and size to a remarkable degree of perfection. The products of the furnace consist of continuous gum- work porcelain dentures, the making of any desired form of teeth for sectional block work, the changing of forms of sectional gum teeth for rubber work, the making of any desired form of pivot teeth or any style of tooth crown to be found on the market, and a variety of original forms that could not be made as articles for the trade, but must always be the result of each dentist's brain. The building up of roots, the enlarging of undeveloped teeth, porcelain bridge work, etc., are among the most important features of modem dental art that are made practicable with the aid of a gas furnace. 'r t'^ \ -I. 16 lUprinUd from •• IndepemUnt Practitioner" of Auguit, 1887. METALLIC ENAMEL COATINGS AND FILLINGS. Read Before the Central Dental Aiaociation of Northern New Jersey. By Dn. C. H. LAND, Detroit, Mich. In the absence of practical demonstrations it is difficiUt to comprehend all the advantages brought about by improvements. The accompanying engravings, Figs. 1 and 2, are taken from practical cases that have at this date been in use for one year.* In the case represented by Fig. 1, the patient was about sixty years of age- The right lateral incisor was pre- pared with a Howe post, shown in its relative position. The five remaining teeth, after the cavities were prepared, contained tooth substance as represented by the dark surfaces, the white repre- senting the lost portion of each tooth, restored with sections of fio. i. porcelain made to imitate the ex- act color and contour of the original tooth substance. The cavities are prepared as for gold filling, when a thin piece of annealed platinum plate. No. 35 standard guage, is placed over the tooth, and by means of burnishers made to take a perfect impression of the outer rim of the cavity, after which platinum pins are attached as shown at A. The object of the pins is to serve as a fastening, both for the porcelain paste or body and as retainers to hold the completed section in the cavity of the tooth. The porcelain paste or body is built upon the platinum disk and made to imitate the lost portion of the tooth. It is then baked in a gas furnace, requir- ing but twenty minutes for the first biscuit and fifteen for the second, and when finished it appears as shown at B, ready to be cemented with oxy-phosphate. C and D are modifications for the other teeth, and Fig. 2 iuastrates porcelain facings for molars. The especial feature of this system, to which I wish to call your attention, is the large amount of tooth substance preserved above the gum, there being no necessity for telescoping the root so far below as to sever the tissues. This mode of practice also dispenses *August,|1888, BtlU in excellent condition. ■ki ■vi>^>isia:K^SMI»- 1, 1887. .LINGS. 1 New Jeri'^y. ia difficult to »vement8. The from practical * In the case years of age* The cavities ce of annealed over the tooth, ) impreBsion of ns are attached as a fastening, lers to hold the porcelain paste e to imitate the Eurnace, requir- L for the second, to be cemented the other teeth, nsh to call your preserved above the root so far se also dispenses Krfi. 2. 17 with the long operationn and pro tra?ol(l loiif i 11 fiihtouiiig, Hp 118 retainorH for ploted Hedtions, portion of tho UB cemented in e prepared sec- 'igs. 3 and 4, ly is built upon 18 to imitate the he lost portion )wn in Figs. 5 en placed on a )d- in a gas fur twenty minutes and fifteen for completed, they I in porcelain of natural organs, jrfectly, both in They are then 18 18 20 OMiiKiitod ill Mu< ciivity, ei Ihor with gut ta-pi'rcha till ing or oxy phoBphatit coiucnt. When tlio anterior side of ii itiolur or bicuspid is dt>('ayile and easy one. Figs. 17, bS, H) and 20 art' a modilicti tion. Fig. 17 represents a tooth filled witli gold, having two pins attached. Fig. IN is a platinum disk, with tubes adjusted to correspond to the position of the pins in Fig. 17. l'oic(0ain body is built about the tulles, and when fused in the furnuce the whole will form a j)orc«*lain crown as shown in Fig. IW. Fig. 20 illustrates the relativt* ^)osition of the tubes, which are designed to form countersinks for the pins in Fig. 17. When cemented in place, it makes a very durable and beautiful piece of work. Fig. Irtisan incisor construct«'d in a similar manner. From this will be seen the great advantage of being able to have the porcelain in a plastic state, as it enables the dentist to perfectly adapt the form of eacih peculiar case with the utmost precision, and this could not be so admirably done with manufacture*! crowns. j In bringing this new mode of practice to the notice of the den- tal profession, I wish to call especial attention to the lai-ge amount of tooth substance preserved. In nearly all the modern systtnns of crown work there seems to bo too much good tooth material cut away, and I think a careful investigation will demonstrate this new process to be far superior, making it possible to save the greater portion of the crown, it not being necessary to cut beneath the gum. In nearly every case, sufficient tooth substance can be retained to preserve the pulp alive, and when the teeth are devitalized, the major portions of the crown can be left intact, serving for retaining purposes and making it unnecessary, in the majority of ceases, to resort to screws or posts. Fig. 10 illustrates a section of poi rmim.roiiH (.pportiuiitioH prpneiitwi in which thin ponvhiiii pniTPHH will pruvo to Ik. of «r..at vnhi.', ih iilmont without limit, ami biiH .'nal.hnl n... to prnctico .lontiHtry on an ontiroly n.w Immn, hh that to (lay 1 oat. Hay t.v my pationt^ that thoir tooth can Iw i..«rfi.ctly roHtoml. I«)tb in appoaranc Hticl nw.fulnoHH, no n.att».r how l.a.Uy thf.y aro .l.'cny..a. No pnlpH will ho red in Hhape, color and Hize, with very little pain or fatigue either t« the ojwrator or patient. FILLING TEETH WITH SECTIONS OF PORCELAIN. ('ATtNTro Dbckmiikh 80th, IHHT. starting from the HinHllest sized approxiinal cjivitioH in the teeth, it in now poHHible to restore the i)roper color iu the most perfect manner; and when we take into conBideration that this proceHH can be continued until the entire tooth becomes in- volved, also that an th(. proctly nr how liiully ry littlo tooth )her (Iniii Ih DUH mnUotinR l^^ain, yet the ize, with very )ROELAIN. ^viticH iti tho • iu tho moHt ion that thifi 3ntinuoiM and iiiKMi t'tToctniil work iM^^iuH I'late A illuBtrfttes decay on tho audrior HnrfacM, j>rp Montiiif^ an cxi **!!ont oppor tuiiity for tliis cla«K of work. Soo Plate B, Hhowing mm-- tiims or |iorcolain comontod in tho cavity; and, althon^^h I'iuk u thoontlinoH of tho joint may be Homowhalp«)i'opiiblo, it is not uoarly HO conMpi(;uouH aH tooth tilled with ^uid or amalgam, and when care is taktMi to make a close joint they are almost iinpor('o[>tibl<>. IMato C illuHtratos other mmliticatiotiH, sliowiii^j a sli^fht irru^ti larity. Impurfections of this character can lie (iorroctod and made to appear as H««on in IMate D. 'I'he manner of securing a practical and durablo fastonin^,' dovico is shown in Plate E. The cavity is propannl as soon in Fij;;. M. A thin piece of platinum is burnished into tho cavity, and then holes are drilled through this matrix, through which (ilatinum pins are passed. A piece of wax is then pressed on to the pins and the matrix. This holds I'uATB 1) lioth in position until invest ment. When the wax is removed and porcelain body put in its place, and when completed, would appear as seen below. 1 2 3 I'J.AIK K. I'l.ATK IV, Fig. 3, Plate IV, illustrates the appearance of the prepared cavity and the completed section ready for adjustment. It will be observed that in the preparation of the cavity it is cut abrupt in order to avoid any thin edges of the porcelain. See Figs, 2 and 3 in Plate V. 1 LATK V, Tho sectioriH of porcelain aro preparetl in tlie following manner: First prepare the cavity, and tben bnrnish a thin piece of annealed platinum plate into the cavity. This will form a mold or matrix— a metallic inipre.ssion — the exact counterpart of the cavity ii' the tooth. A^■hen the matrix is established in place in tho cavity of the tootli, three holes are drilled through the prepared matrix and into the dentine of the tooth. Platinum pins are tl>en passed through the matrix and into the holes in the dentine. Wax or moulding compound is then pressed into the matrix. This adheres to the matrix and the pins, and holds them in their exact position ready for investment. The investment is composed of equal parts of asl)estos and plas- ter of Paris. This will 'hold the pins in place during the baking. PORCELAIN FILLINGS AND OKOWN SECURED BY SCREWS AND ANCHORING DEVICES. Plate VI., Fig. 1, illustrates screw passing through the porcelain and into a nut that is held in place by means of oxyphosphate cement. This establishes the nut firmly in position, and the screw can serve as a very substantial means for securing ~ the section of porcelain in place. In some instances it might be of advantage to use a solution of gutta- percha between the filling and the wall of the cav- ity, and thus have an indestructible cement that W \l will not wash out; or this section can be forced on plati: VI. to a lining of sponge gold, Eobinson's felt foil, etc. CEMENTS. There seems to be a great want of confidence in the stability of cements, and the smiirising feature of this outcry, is especially directed against the introduction of this new process, just as though there could be any practical difference between the same application of '^e cements in this particular instance and the various other methods that are constantly practiced, and which are the mainstay of some of tho most expensive and valuable results in modern dental cavity of the itrix and into ssed through or moulding dheroa to the yosition ready stos and plas- ,he baking. URED BY IS. the porcelain oxyphoaphate ind the screw 8 for securing 3orao instances ition of gutta- 'ull of the cav- 5 cement that I be forced on B felt foil, etc. the stability of y, is especially just as though ime application e various other the mainstay of modern dental W D l'I,ATBi VII. 23 art. AVhon wo take into consideration that our whole system of crowning, conii)rising upwards of twenty eight various methods, are almost entirely dependent upon the cements for their proper adjnst- nu'nt, will it not Iw glaringly apparent that either wo are guilty of falsifying to our patients in representing the penuanency of bridge work and all our crown work, else those who challenge the durability of an improved modification of tlie same principles, are blindly pipjudiced. However, in order to accommodate the most incredulous, the following devices may be of interest : (See Fig 1, Plate YII.) The cavity No. 1 is lined with a gold matrix as represented at Fig. 2. This has been formetl by burnish ing a piece of platinum foil into the cavity. It is then removed and gold plate fused over the snrfact" by the aid of the blow-pipe. Thin will form a gold and platinum lining that conforms to the exaci; outlines of the cavity. A hole is drilled in the center, through which a screw passes as shown in Fig. 1. The screw is provided with a shoulder, which is intended to force the matrix on to a solution of gutta-percha, or it may be asphaltum, sponge gold, Robinson's felt foil, or any other indestructible material. The object is to lirst establish a thoroughly reliable foundation for the section of porcelain as seen in Fig. 3. Fig. 4 indicates the com- pleted work, the section being secured with oxy-phoaphate cement. The latter material being between two indestructible surfaces, will bo of little consequence if a portion should become disintegrated. Fig. VIII illustrates an incis- or manipulated in the same 5 manner. Fig. 2 in this drawing ^7^2) illustrates the matrix, 5, adjusted over the screw post, as seen in Fig. 1. Fig. 3 is the completed tooth crown, which is made in the i'latk viii. following manner : The matrix, 5, forms the base or support on which to build the porcelain body. This, when mixed with a sufficient quantity of rain-water — preferred on account of having no lime in it, or distilled water can be had of your druggist— to form into a stiff putty or paste, in this plastic condition the body can be moulded or carved into any desired shape. The body is built on the matrix, 5, in the shape as seen in Fig. 3. It is then u placed in the muffle of the furnace and fused. When removed from the muffle it is then placed in a cold muffle and the air excluded until sufficiently cool, and when removed a shrinkage of about one fifth in bulk will have taken place. This is known as the first biscuit. It will also be observed that cracks have formed ; in some instances the body has separated from the matrix. These inevitablo results make it necessary to resort to the second biscuit. A quantity of body is mixed to a creamy consistency. This is carefully jarred into the cracks, and in order to keep it from flowing out a clean and dry napkin is pressed against the surface. This absorbs the excessive moisture, and then it will be comparatively easy to mould the stiffer body and restore the original carving. It is again passed through the furnace, and should come out almost a perfect tooth in shape. But in order to imitate the natural expression with greater precision, the anterior surface of this prepared base is ground off sufficiently to make room for a prepared veneer, a front having the proper blending of color and shading to correspond with its natural neighbor, a more precise manner than could be accomplished by depending on the mere individual carving and shading before fusion. FOEMING THE MATRIX-Plate IX. A piece of plat- inum, No. 60, is prepared as seen at A. The hole in the center is somewhat smaller than the tulie, E. By means of the small point- ed instrument, as- bestos fibre is made into a rope as shown at B. The P"-*™ ix. tube, E, is then passed over the fibre as indicated at C, and when pa(!ked by means of the instrument it will appear as seen at D. This will be found a very convenient and rapid method of holding the platinum tube firmly in position while soldering it to the base. moved from lir excluded : about one- ac the first d ; in some le inevitable A quantity jfully jarred a clean and absorbs the Lsy to mould igain passed feet tooth in with greater B ground off t having the h its natural mplished by iding before C, and when as seen at D. )d of holding bo the base. 26 PLATINUM PINS. Plate X illustrates a new form of double-headed platinum pins especially designed for the new process, and other O applications, as an important aid to dental operations. In the engraving they are shown soldered to a gold clasp which is intended for rubber work. Also they are PLAT« X. shown attached to both sides of a metallic matnx. They are a very useful device for attaching rubber to gold plates, etc. Both heads are perfecUy flat, and are designed to stand on end without danger of falling during the process of solderina Plate XI illustrates anchoring device. By reference to Fig. ] it will be observed that gold nuts have been previously imbedded in the body of the cement. The screws p^^.^ ^i. are shown as being engaged with them and into the tubes provided for their reception, in the body of the crown. Notice that the screw posts are provided with a shoulder. This is intended to force the metallic plate, Fig. 5, on to a surface of indestructible material The platinum matrix, 4, is designed to tit over the posts, as seen in Fig. 2, and when the porcelain is added, will resemble Fig. 3. Fig. 6 is the completed tooth crown. A SYSTEM OP PARTIAL GROWN WORK. Patbntbd December ao, 1887. These improvements have developed a new and practical method of preparing and attaching artificial sections of teeth which may be appropriately designated as partial crowns. From a series of differ ent shades of porcelain body, these sections can be made to imitate the various colors of the natural teeth perfectly. Fig. 1, Plate A, illustrates a bicuspid with anterior portion of the natural tooth intact, having Howe post attached. Fig. 2 represents a platinum matrix i^te a. n m 1 J 26 that U». !«„ c„,et»ny mtM a.»nt th» ,.»t »»,. b,.™.W to lb. lth. I'll?. 3 illa-trat... the .pl.ro:t.m«l» .urla.'.' o[ mal.u, -!»« ing conntor-sink for tho post or scrtiw, and on the anterior siile part of the fused porcelain body can be seen. This formH a com l>lete section ready to be ^ ^ i'latk b. Lented to the tooth, as shown in Fig. 4. From F.gs. I to ... ,n Plate B, are raos n ended trform a countersink in the completed section, as shown in Fig. 4. Fig. 3 is the completed section showing anterior surface, and Fiir. 5 i« the section cemented in the tooth. „ ;, , „ lleferring to Fig. 1 in this engraving, attention is called to the fact that where a cavity is deep and the | 2 3 4 angles are abrupt, that no countei-smks f-^:^ ,^ ^ f J*-. or screws are needed; also that after the mati-ix has served tho piirpose of form ing the section, the platinum is removed. This leaves a section of porcelain the exact counterpart of the cavity. When _ cemented in place woiUd appear as mT« u. ^'"Xl: E^st modiiicatioa of the same proc.. involving tw. third of the crown of a molar. Fig. 1 indicates that about one-th d St crown is left intact, showing ^arge cavity prepared with ^ t^ lu nn.lercuts Fig. 2 is platinum foil No. 60. This Has been islipd to tlio latrix, show- 5 28, I. I to T), ill be interesting hat it demon ical meaoH of rcelaiu section Bg to posts or especially ap- f. 1 represents Fig. 2 is the latinuni in the matrix, and is tion, as shown iterior surface. s called to the 3 4 I.ATB I). involving two- about one-third pared with snit- This has been len the prepared 87 countersink, Fig. 3, which, it will be observed, has a large-headed platinum pin sold(*red in the interior. This prepared counterflink I 2 3 4 5,6 Platb E. is then carefully laid on the burnished piece of platinum, as shown in Fig. 4. Body is then built about it and fused in the gas furnace, and would appear as seen in Figs. 5 and 0. By carefully burnishing the platinum to the surface of the tooth, every little indentation is nnpressed on the surface; in fact, the platinum takes a perfect impression of tlie tooth. Notice that the countei-sink. Fig. 3, is simply laid on the jilatinum, and not soldered to it, so that when the porcelain body has been fused the platinum can be peeled off. This leaves the approximate surface of the crown the exact counterpart of the horizontal surface of the natural tooth. The countersink being embedded in the central portion, the adaptation can be made remark ably perfect. The cavity in the tooth and the countersink in the crown is then filled with cement, and the two pressed together and allowed to harden, making a very desirable and durable piece of work. A DEVITALIZED CENTRAL INOISOR. Patented Jdly l()rH, 188S. No. 1 illustrates the anterior surface reduced about one-half the thickness of the tooth; Fig. L is platinum matrix; Fig. M, porcelain veneer; Fig. 3 is platinum matrix and veneer fused together; Fig I .2 3 Plate F. 2, the same adjusted to the tooth. This has proved to be a very satisfactory method of restoring the color of teeth, in place of the usual mode of bleaching. 28 Reprinted from l/w ' ' Independent Praelitioner " of August, 1886. A NEW SYSTEM OF RESTOEING BADLY DECAYED TEETH BY MEANS OF AN ENAMELED METALLIC COATING. By Dk. C. H. land, Dbtroit, Mioh. This invention consists of a coating of platinum made to lit the ontside of the teeth, after which the anterior surface is coated with a porcelain enamel front, made to imitate the natural organs so perfectly that the art is concealed. Many of the long and tedious operations, where it has been deemed necessary to insert large and conspicuous gold fillings, may by this process be avoided, while better results are attained. Fig. 21 is a typical case, where in place of inserting the usual gold fillings, the anterior surface may be ^^^^^ reduced by means of small corun / lnBnll9^K^\^S. ^ dum wheels used in the dental engine, U'#B-j(__J^[iiJU' ^ indicated in Figures 1 and 2, F'" «» Plate A. Fig. 13, Plate B, is the prepared crown, ready for adjustment to the same by the use of oxy-phosphate cement. Fig. 22 repre sents a typical case of undeveloped lateral incisors, which can be enlarged to the proper size by the same means. Fig. 4, Plate A, represents a decayed molar. Fig. 8 is the same prepared to receive the amalgam filling, which, when suffi- ciently hard, is prepared as shown in Fig. 12, ready to have the crown. Fig. 16, cemented to it with oxy-phosphate cement. Fig. 9 is a central incisor. Fig. 10 is a cuspid and Fig. 11 a bicuspid. Figs. 13, 14 and 15, the crowns ready for adjustment. Those who object to the use of amalgam may. use white cement or gutta-percha for fastening. The manner of procedure in the case of devitalized and discolored incisors is first to prepare the teeth as shown in Plate A, Figs. 1 and 2. Then a thin piece of platinum plate, No. 30, standard guage, should be fitted accurately to tie Fig.sbj. tooth, forming a hollow shell. Enamel fronts are now ground to tit, as shown in Figs. 17, 18, 19 and 20; after whi:!i fu./ are fused to the platinum in the same manner as continuous gum work, by 1986. TEETH BY ade to tit the I coated with :al organs so ; and tedious jrt large and roided, while case, where e usual gold rface may be small corun- lental engine, )s 1 and 2, )r adjustment ig. 22 repre which can be ?ig. 8 is the 1, when suffi- y to have the nent. Fig. 9 II a bicuspid, i. Those who • gutta-percha Si. low ground to h«. / are fused gum work, by 99 iieing a porcelain body prepared expressly for the purpose. By thp use of Land's Gas Furnace this can be done in ten minutes. The enamel fronts and body are also manufactured and for sale by the Wilmington Dental Manufacturing Go. F\{f. 9 represents a central incisor built up with amalgam or cement, to which the platinum is closely fitted, after which the enamel front. Fig. 17, is ground to fit and fused to the 'shell, as Hhown in Fig. 13, ready for adjustment to Fig. 9. Figs. 10, 11 and 12 are modifications for canine, bicuspid and molars, ready to receive the prepared coatings, Nos. 14, 15 and 10. Plate A. In introducing this clasq of work to the dental profession, a means is afforded through which a much better artistic effect can be attained and the preservation of a larger amount of tooth struc ture be secured. Add to this the fact that there is but very little pain or fatigue, either for the patient or operator, and it will l)e doubly appreciated. During the past year tins class of work has been thoroughly tested as to durability and found to be much more reliable than gold fillings. In large contour work the frail walls of the tooth must be the main dependence of support, while with the hollow shell the weak tooth is held together. Thus it will be seen how much more complete is the preservation of tooth substance, it not being neces sary to make undercuts or retaining pits. A young lady recently presented herself with both central incisors broken off by accident, the left one having lost about half its crown, with complete exposure of the pulp, the right one having only about one-sixth of its substance gona Her teeth were unusually 80 woll preHorvod, while they were large and (jiiite connpicnioUH, The right ct^ntral was oanily restored to a good contour by a httle {jriud- ing. The left, after necesHary treatment, was simply ^jronnd down njOTn the anterior surface, an operation demanding Iobh than ten niinntes of time. In twenty minutes more a platinum overcoat was litted to it, and the enamel front ground to it. This corapU'ted the first sitting. In tlje afternoon of the same day it re»- 1. A< illustriitos llio HhH|)»' ill which to proparo tht< orowu l)y rtMlnciiijj tho imturnl tooth HultMturico. Fig. 2, A, iiuliciiteH tho hhiiio Hliape Imilt on a root. V'\ff. 8 in the platinum matrix, Hhowinjj its projter Hhape and havinj* pinH attached. Fij;. 4 in the com |)leted metallic overcoat ; C, (', veneer. When the matrix is ready aH shown in Fijj. 8, the first staj^e of the operation in to lay a coating of liody about the pins, filling the (lepreHsion ho as to produce an angle as Heen in Fig. 1, A. Jt is then i)aHKed into the furnace and the l)ody fused to a glaze. It is thea removed and placed into a cold mullle to cool. This is known as tho first biscuit. At this stage of the process it is ready to receive the veneer, as shown at Fig. C, C. The veneer is h -.'urod by placing a portion of tody between it and that which bft^i been fused to the base. Fig. 3, when it is ready for the final bala, and would appear as shown in Fig. 4. INCIDENTS OP OPPIOE PRAOTIOE. Patient, lady of 30 years, presented tho inv^Tidar position of the root of left lateral incisor. An artificial tooth ( rowu, Logan pattern, had been adjusted to the root, but ]»roved to be unsatisfactory. This singular defect was restored in a most satisfactory maniier as follows: The Logan crown was removed, and a screw-post ad- justed as seen in the engraving, Plate R. The platinum telescope as shown beneath, was made to fit over the root and post. After pj^^^j, ^^ the telescope is removed— being in the form of a tapering cylinder — it will be found necessary to first grind off the lingual surface in order to have it present corres- jionding angles with" the adjoining teeth. Having cut away this portion of the cylinder, a piece of plate is cut, and then burnished to conform to the shape of the angle of the lingual surface of the cor- responding members. It is then soldered with pure gold to the 8» •••••l cyliiulor. 'I'he noxt Htiip' of the operatit)!! i« to ^riud tho mitorior Hurfiu'n of tht> cyliiulHr very thin; then adjiiHt it to the root. Hold it firmly in ity placo until, by iiioanH of n rouud-i>ndi>d burii- nisher, it can Im> inulloted in Buch a iimnuer bh to rtMhice the front HiitViciontly tt) imiko room f(jrtho ])repiiro(l voueer. In the engraving, Plate S, the com- Pi^tk s. pleted operation is whown, indicating that not only the veneer han hoen fused to the prepared cylinder, but also a portion of artificial gum was added; thus restoring the proper length of tooth and completely concealing the position of the abnormal root. In many instances Ixjth tooth substance and gum can be restored artilicially, and to a degree of perfection that will be a surprise to the uninitiated in the art. Miga , 14 years of age, healthy and well developed, except the defect in the teeth, presented a condition as illustrated in the engraving Fig. 1, Plate G. This will be interesting both to the dentist and the physi- ologist. Notice that the roots of the teeth have grown to almost their nor- mal size, and are evidently still progressing. It will be observed that the enamel of BKIfOBB THE U'LATUQ] OPBRATION. UUBOl *ou unci. the crowns is perfectly developed for a short distance from the roots, and that it ends abruptly, the rest of the crowns showing a want of development, principally on that portion of the teeth where enamel alone should form; it will also be seen that the defect involved all of the front teeth and a portion of those at the back. On the lower jaw marked traces of the same defects were apparent and correspond to the same conditions as above. The indications are that in childhood local causes had in some way retarded the building up of the functions during the greatest period of the development of these particular teeth, which was verified by the statements of her parent, who informed me that her daughter, when a child, had been in feeble health for several years, and this after a severe attack of scarlet fever. Here then is a beautiful illustration of the 84 allied int(«reHtH of medicine nrul dnntiHtry. Kvitlently tho |)riiuiiry caune of th« (Uwiiwe originated at that period of life when the application of medical Hkill wbh the only reme thnt tho iintiiKoniHraB wouUl l» ti»<« Hiiino aH when tli« t«HlHt.itmm hii<1 iridium was umjmI; tlio objwt Hounlit wftH to liavo tho inotal aH thin HH poH»iUU> and at thi» Hanio time be Hnrtlciently Htron^ to withntand the nm . mired in manticatiou, etc. AIho reab/.inK tlio advantage of liiiviriK ihe metal coatH uh thin aw jxwible about the neckn of the teetii, which would Hocure a very clone adaptation and take up the leaHt Hpace between the roots. In this alloy the desirable q)ialitieH wore found especially for the lower incisors. FiR. 1, I'lftte J, illustrates the appearance of the work when complete.1, and is at present giving the utmost satisfac- tion. Four years previous these teeth had been built up with gold APP«AmANO« AFTBH IPLATB J.-FIO. 1.] BEOTOIUTION. by an experienced and careful operator, but as usual the gold had gradually become battered down and completely worn off. In com- parison I have a large number of crowns that were adjusted to the roots of teeth eight and ten years ago, and this was done in a crude way, and at the present time doing good service. I therefore can speak with confidence as to the greater durability of this more perfect method of adjusting porcelain coats, sections and fillings, whereby every possible condition of decay can be arrested and the teeth restored perfectly to their natural appearance in shape, size and color. Add to this the fact thfct these operations are accom- plished without pain or fatigue to either the patient or dentist, that the long and tedious malleting is dispensed with, the protracted use of rubber dam not required; therefore will it not be considered as one of the greatest boons to suffering humanity. VALUABLE ADVIQE. Do not imagine that a blacksmith's bellows will answer the pur- pose of an air supply for the furnace; while it may have plenty of volume, it lacks the pressure. Nor will hydrostatic apparatus do; it may furnish the pressure, but lacks the volume. If the gas meter is more than thirty feet from the furnace, and the supply of gas not enough to give a rich and full volume, it will be due to want of pressure at the works, or to the small size of the pipes at the point of delivery. When there is not enough gas the first step will be to have the pipes replaced with a three-quarter-inch main from the meter close up to the furnace. IMPORTANT. The iTibber tubing connecting with the bellows and the furnace should be as short as possible. The longer the pipe the greater friction there is to overcome, and strain on the bellows. Also the increased work of the operator will be materially affected. Even one foot of extra pipe will make a decided difference, not only with the extra exertion of the operator, but the lack of a strong jet of air into the burner will retard combustion, thus interfering with the successful operating of the furnace. A piece of wire cloth — very fine mesh — should be placed over the air supply pipe or at the orifice of the blower. This will pre- vent any small particles of dirt from getting into the small tubes of the blow-pipe to clog them. NECESSARY MATERIAL FOR PRAOTIOING THE ART. For preparing sections for fillings. Platinum Foil No. 60, standard guage, is the proper thickness, and for large cavities No. 50 or 55 is recommended. For making the telescopes for crown work use Nos. 28 to 32 Plate. All should be well annealed by heat- ing with the blow-pipe to a white heat. Where the lower front teeth are to bo crowned an alloy of Platinum and Iridium is used. This is much stiflfer and can be rolled to No. 35 Plate. Where it is desirable to take up less room between the roots of the teeth this is recommended. . '- '^ There are now five standard shades of bodies or enamels, put up in one ounce packages; and by mixing these in various propor- tions a great variety of tints may be had. Also a great variety of -=r«*si«*p*rftr 37 prepared veneers, representing the anterior surface of each class and size of teeth, are put up in packages of 100, assorted incisors or molars and bicuspids, or cuspid.-'. Long and short flat-headed Pl-itinum Pins may be had, put up in dozen or two dozen packages. These are very useful in making attachments for fillings, for clasps, for rubber work and backings, for plate, teeth, crowns, etc. THE WILMINGTON DENTAL, MANUFACTURING OO., WILMINGTOII, DEL., Are our Agents for these goods. Price of Body, per ounce, $1.50; Veneers, per 100, $8.00; Platinum Foil, 60 cents per Dwt.; Platinum Plate, 50 cents per Dwt; Platinum Pins, 36 cents per dozen; Asbestos Fibre, 50 to 75 cents per pound; Muffles, large size, 8 inches, $1.25 each; Muffles, small size, 60 cents each; Round Slides, large, 10 cents each; Round Slides, small,. 5 cents each. . ,. Mi' ■' X .f ' " ■, . . ' '/.''• ". ■ ■' - f it f.'i -' ; .' ,'; . '»' .'j. r.rl \i ,■ ?;;.'• .'■ 't , ..■7 ,; ••' . p; ■ -J 't 38 TO THE DENTAL PROFESSION. In dividing our interests, it has not been without a careful consideration of the rights and the protection of others as well as our own. Of the several methods of handling patented inventions, and after testing other ways of making our interests mutual, have i and the license plan the only practical and satisfactory method of securing equal privileges to all. We realize that these improvements are to be observed strictly as an art, and do not expect that every one who may assume to so pr»M5tice it will be successful. Our terms and conditions may have a t^iXiAency to keep many from investing. This we anticipate, but are of *Jie opinion that better protection will be maintained by uphold- ing the highest standard in excellence of products, etc. The first mutual act vnll be the opening of our office and laboratory, free to instruct all those who will see enough value in what we have to offer for reasonable considerations. We cordially invite an investigation, and feel sure of being able to offer a series of improvements that have a real, substantial value. Dr. Land has, for the past eighteen years, enjoyed a select practice exclusively with the wealthy and influential citizens of Detroit and vicinity, making a specialty of high grade dental operations, both in the mechanical and operative branches of the art, and hereafter will give especial attention to visiting dentists who wish to investigate. By permission, the following names are refeiTed to : Daniel Scotten. Esq., Tobacco Manufacturer. Jerome Croul, President Detroit Fire Commissioners. George W. Moore, Attorney. Emort Wendell, President First National Bank. J. W. Weeks, City Directory Publishing Company. Hon. C. I. Walker. Col. G. 8. Wormer. Hon. Moses W. Field, Regent University of Michigan. George Thrall, Detroit Machine Screw Works. Thos. a. Parker, Esq. Hon. E. C. Walker. A. M. Parker. Wholesale Grocer. C. G. Freeman, Pontiac, Mich. Gbo. Farwbll. Also we refer to the names of a number of our licensees : Drs. Barber & Kline, Toledo, Ohio. Dr. C. Thomas, Des Moino. BMorar.