Dental Fillings

FILLINGS, FILLING. The process of filling consists of taking small pieces of cement with a filling instrument, introducing them into the cavity, and condensing them well against its walls and floor. In this way, the entire cavity is filled. After this, all the contours of the tooth lost to caries are reconstructed from the cement. One should not build up particularly high edges and corners from cement, as it does not possess great durability. When the filling is ready, it is covered with sandarac or collodion, thanks to which a film forms on its surface, protecting it from the influence of oral cavity fluids, at least in the first hours, until the cement has completely hardened. Some brands of cement include a neutral varnish for this purpose. It is also possible to coat fresh cement fillings with paraffin, which is melted on a spatula over an alcohol flame. Paraffin surpasses all varnishes proposed for this purpose to date and protects the filling from chemical influences for several hours. Grinding and finishing of cement fillings are performed with carborundum stones and wheels, paper discs, etc. It is best to perform the finishing of the filling on the second day. The described filling methodology applies to all cements in general. When working with silicate cements, one must try to mix the powder with the liquid into a thicker mass; however, this thickness should not be achieved by quickly stirring a large portion of powder into a small amount of liquid; on the contrary, the thickness of the cement paste is achieved by gradual and energetic stirring of the powder into a sufficient amount of liquid, and the slower and more energetically the powder is ground, the better the consistency of the filling. Silicate cements do not possess the same stickiness as phosphate cements, and therefore one cannot rely particularly on their adhesiveness and must pre-emptively take care of fixation points within the cavity itself. Filling instruments must be smooth, and their working part—heads, burnishers, etc.—must be made of stainless and non-oxidizing metals in order to preserve both the color and chemical properties of this material. The most insignificant reactions significantly alter the transparency and color of silicate cements. Finishing of silicate fillings is performed on the second day or 3–4 hours after filling, and both the stones and paper discs are best covered with petroleum jelly so that there are no scratches on the filling and so as not to deprive it of its luster. With a good selection of color, it is possible to achieve a completely normal tooth color, for which it is sometimes necessary to mix powders of two colors. Filling with gutta-percha. Since gutta-percha is used for temporary fillings, no special preparation of the cavity is required. The use of cotton rolls to maintain dryness in the cavity is quite sufficient. The technique of filling consists of heating the gutta-percha over an alcohol flame and introducing it in small pieces into the cavity, where it is subjected to condensation with ball-headed instruments. After filling the entire cavity, the gutta-percha is smoothed toward the edges of the cavity with a heated burnisher and the filling is given the necessary shape. When using hard varieties of gutta-percha, smoothing the filling is easily achieved by lubricating it with chloroform.

Filling with porcelain, porcelain inlays. There are two methods of filling with porcelain inlays: the Jenkins method, in which the porcelain inlay is fired in each individual case according to an exact gold mold, and 2) the Dall method, in which a pre-made inlay is precisely ground to fit the cavity and secured with cement. The Jenkins method is more widespread. All work using it breaks down into 5 stages: 1) preparation of the cavity, 2) taking an impression, 3) asbestos lining of the impression, 4) layering and firing of the porcelain, 5) securing the inlay. The cavity prepared for a porcelain inlay must meet the same requirements as for a gold inlay. In cases where the edges of the cavity cannot be removed, if it is desirable to preserve them despite thin parts of enamel, this can be achieved by forming a base of phosphate cement in the cavity (Figs. 28 and 30). In any case, the edges of the cavity must be thin and smooth, which is achieved by finishing with subsequent polishing. Obtaining an impression. For this purpose, gold foil is used—"Standard Gold R. V. Williams" No. 30. A piece of foil of the necessary size, square or oblong according to the shape and size of the cavity, is placed over the cavity and gradually pressed into the cavity with light pressure using cotton pellets so that the entire cavity is lined with gold foil and the edges of this foil extend onto the enamel of the tooth (Fig. 41); they must be firmly pressed and smoothly burnished to this latter so that there are no folds on the gold. In deep cavities, and especially with careless manipulation during the pressing of the gold foil into the cavity, tears occur in one area or another adjacent to the floor of the cavity. This is of no particular importance, provided the edges and their transition into the walls of the cavity are well preserved. This gold impression is the exact shape of the cavity with all its features, and the filling is formed and fired in it; but for this, it is first fixed in a special muffle with asbestos. This is necessary so that the thin foil does not change its shape during work from being touched, and also to prevent the influence of the high temperature during the firing of the porcelain, which could also change the shape of the impression. Asbestos lining. The best packing material for this purpose is powdered asbestos, which, with a small amount of water, gives a mixture of cream-like consistency. Asbestos is placed in the form of a mound into a special nickel or platinum muffle (Fig. 13), and the gold impression is placed on it. After this, holding the muffle by one ear with a hand or tweezers, it is tapped slightly on the table until the asbestos spreads throughout the muffle; the gold impression descends with it almost to the very bottom of the muffle. To cover the free edges of the gold, the liquid asbestos is moved onto these edges with a blunt probe, leaving the edges of the cavity pressed into the gold foil free of asbestos, so that the asbestos lies in the form of a rim around the edges of the foil corresponding to the edges of the cavity. These edges will provide a clear direction for the future contours of the filling (Fig. 12). As little asbestos as possible should be taken, as a thick layer of it in the muffle requires significantly more time for firing. The asbestos-lined impression must be well dried. However, asbestos hardens so slowly that it would take at least a day. Therefore, it is best to remove moisture from the asbestos with blotting paper, which is placed around the edges of the asbestos in the muffle. When all the papers become damp, they are replaced with others until they remain completely dry after contact with the asbestos. After this, the muffle is grasped with tweezers and passed several times over an alcohol flame, which evaporates all the remaining moisture in the asbestos and it becomes dry and reliably fixes the impression. Layering and firing. Both these stages of work on manufacturing porcelain inlays are so connected that they must be described together. In a small mortar, preferably in a special glass cup, Jenkins porcelain powder is dissolved with alcohol to the consistency of a liquid mass. Even if the mixture is very liquid, this is of no particular importance, as the excess alcohol quickly evaporates and the porcelain mass becomes dry. By adding alcohol drop by drop from a pipette, the necessary consistency of the mass is again achieved. When the mass is ready, it is picked up with a fine brush and applied in layers onto the foil inside the impression, and one should not fill the entire cavity at once, but do it gradually, in several steps, according to the size of the cavity. When layering the porcelain mass, it is very important to keep the edges of the impression adjacent to the asbestos in absolute cleanliness so that after firing, there are no teeth, irregularities, etc., on the edges of the filling (Figs. 8 and 9). After applying the first layer of porcelain mass, one can proceed to firing. For this purpose, there are furnaces of various systems; it is best to use a Mitchell electric furnace with a rheostat and pyrometer (Fig. 18). The design of all furnaces has the same principle. A muffle with porcelain is placed in the furnace, it is quickly heated, and when the temperature inside it reaches the melting point of the porcelain, the latter melts and produces a shiny, smooth mass. The melting point of the Jenkins mass is 850°. A major drawback of the Jenkins porcelain mass is its shrinkage after firing. This circumstance necessitates repeated layering of the porcelain mass and repeated firings. Usually, even small fillings require at least 3–4 layerings and firings until all the contours of the filling are completely built up. Thus, by gradual layering and firing of the porcelain mass, it is possible to reconstruct from porcelain all the missing parts of the tooth—the corners of incisors and canines, as well as defects of the labial and buccal surfaces of other teeth. Jenkins restored deeply carious wisdom teeth with porcelain fillings, and these teeth were preserved for a long time (up to 25 years).

Securing the filling is also an important moment of the entire work. As soon as the firing is finished and the filling is ready, it is freed from the asbestos and gold foil, and it is very important that not a single piece of gold, not a single point, remains on the inner surface of the filling that could prevent the filling from seating well in its place. Usually, all the foil is easily removed with tweezers or a probe; often, however, one has to resort to drilling off the remnants of gold foil stuck to the inner surface of the filling, and here one must exercise special caution not to touch the thin edges of the filling with the bur. It is suggested to place the filling in a glass test tube with aqua regia and pass the test tube over an alcohol flame until the aqua regia boils. In this process, the gold particles stuck to the filling dissolve. This method has negative properties: under the influence of aqua regia, the porcelain filling changes its color. When the entire filling is cleaned of gold, it is tried in the carious cavity, and if there are any thin jagged edges on it or excesses on the inner surface that occurred under the influence of the gold foil breaking during the taking of the impression, they are easily ground off with thin carborundum disks. If the filling corresponds in every way to its cavity, i.e., if the edges of the cavity tightly connect with the edges of the filling, if the contour parts of the filling are correctly constructed and compensate for all defects of the tooth, then after checking the articulation, one can proceed to securing the porcelain inlay with cement. For this purpose, several grooves are made on the inner surface of the filling with a diamond disk, and this surface is made rough. Likewise, it does not hurt to make anchor points or grooves in the cavity itself, wherever and however possible. All this will contribute to better fixation of the inlay. Grooves on large fillings are best made in a crosswise direction, and also slightly away from the edge of the filling (Figures 34-36). Then the carious cavity is well dried with alcohol and ether, filled with thinly mixed cement, and the inlay is inserted into it, pressing it to the bottom of the cavity with a finger or a special wooden stick. It is also possible to seat the filling-inlay and press it against the walls of the cavity with an ordinary silk thread using a surgical knot (Fig. 39). Dahl-Gutmann inlays. The method of preparing porcelain inlays, according to Jenkins, is very painstaking and requires great skill and much time. Dahl's inlays significantly simplify the process of filling with porcelain. For this method, ready-made ground mineral fillings are used, which fully correspond in their luster and color to the porcelain fillings already described. Corresponding to each size of inlay, there is a corresponding bur, with which the carious cavity is formed. This method is applicable on the labial and buccal surfaces of teeth. A complete Dahl set consists of 100 sorted, round inlays with attachments, 46 burs for straight and angle handpieces of the dental drill, 4 holders, 1 gauge, and 2 diamond disks (Fig. 19). The work methodology is simple. A bur of the necessary size is chosen, which would correspond to the size of the given cavity, and the cavity is prepared (Fig. 31). Corresponding to the size of the bur, an inlay of the same size is taken and secured, like other inlays, with cement. The inlay is usually grasped by the attachment from above (Fig. 40) and pressed into the cavity, lined with thinly mixed cement, until the excess of the latter is displaced from it. The inlay itself already has grooves that facilitate its fixation in the cavity, and the very shape of the cavity already fully guarantees this fixation. After the cement hardens, the attachment of the filling is cut off with a diamond disk, and the filling is polished with stones and paper disks in the usual way. Gutmann simplified Dahl's method by proposing his own mineral rods instead of ready-made mineral inlays. The method has the advantage that many fillings can be prepared from one rod, which are cemented in the cavity and polished, just like Dahl's inlays (Fig. 17). Dahl-Gutmann inlays, provided the cavity is located in a suitable place and is central, provide great time savings during work and fully meet their purpose. The advantages of porcelain fillings consist first of all in the fact that they absolutely match in their color and have a shiny enamel surface, which makes them completely invisible: they are so smooth that food particles do not linger on them, and therefore recurrent (secondary) caries forms extremely rarely near such fillings. Among the indications for the use of such fillings, one must point primarily to considerations of a cosmetic nature. At the same time, it is necessary to emphasize that even on posterior teeth, especially in cavities extending deep under the gingival margin, porcelain fillings are indispensable. Unfortunately, however, porcelain fillings cannot be proposed for mass use due to the complexity of working with them. Combined fillings. At one time, it was proposed to mix amalgam with cement. Such a combination imparts to the filling material, on the one hand, the properties of cement—stickiness and rapid hardening—and on the other, the properties of amalgam: significant resistance against oral cavity secretions. Mixing is performed in two ways: either amalgam is added to already thinly mixed cement, or a certain amount of cement powder is added to the finished amalgam, and the entire mixture is thoroughly mixed with an insignificant amount of liquid. The filling technique is the same as when these materials are used separately.