DENTISTRY 181 



Thoroughness of local treatment by which every vestige of foreign matter adherent 

 to the exposed tooth surfaces is completely removed is now recognised as essential to 

 the cure of the disorder. 



In order to achieve the necessary thoroughness of instrumental cleansing of tooth 

 surfaces, great improvement in the number, character and adaptation of special in- 

 struments has followed, and the necessity for continued prophylactic treatment both 

 by the dentist and the patient is recognised and insisted upon. In the more serious 

 forms of alveolar disease, those complicated with a systemic or general nutritional 

 disorder, attention must necessarily be directed to the correction of the impaired 

 constitutional state; and as in such cases the general resistance of the individual to 

 bacterial infection of the pus-producing variety is usually found to be less than normal, 

 much therapeutic value lias been derived from the administration of properly graded 

 doses of autogenous vaccines derived from cultures of the organisms taken from the 

 pus exudate about the affected teeth. The application of serum therapy to the treat- 

 ment of alveolar pyorrhea must, however, be made with intelligent regard to the nature 

 of the case if curative effects are to be derived from its use. In properly selected cases 

 where the selection is based upon a correct diagnosis of the origin and nature of the 

 disorder the use of serum therapy has given most satisfactory results. 



The restorative procedures of operative dentistry have been greatly improved in useful- 

 ness and artistic quality by the development of the "inlay method" of filling cavities result- 

 ing from tooth decay, and by the improvements made in the composition of plastic filling 

 materials, which make possible the restoration of lost tooth structure by materials so closely 

 simulating the texture of the teeth as to render the repair unnoticeable. 



The so-called inlay may be of metal or of porcelain. Gold is the metal used almost exclu- 

 sively when a metallic inlay is to be constructed. The procedure is the invention of W. H. 

 Taggart of Chicago, and consists essentially of making a stopper of specially prepared wax 

 to fit the previously cleaned and shaped cavity in the tooth, in all respects of the same form 

 as it is desired that the finished inlay shall assume. The wax model of the inlay is then with- 

 drawn from the tooth cavity and embedded in a mixture of clay and plaster of Paris contained 

 in a small ring-like flask, so arranged that a gateway reaching from a concavity formed in the 

 free upper surface of the investing mass shall communicate with the wax form embedded 

 in the centre of the flask so as to permit the passage of the molten gold to the matrix left in 

 the investing mass after the wax model has been removed by heating the apparatus to a 

 temperature that completely dissipates the wax. Pure gold fragments are then melted in 

 the concavity in the surface of the investment by means of the flame of a compound blast 

 lamp burning a mixture of nitrous oxide and illuminating gas. At the moment of fusion of 

 the gold the cover of the flask is forced down upon it by means of a lever which simultaneous- 

 ly opens a valve admitting nitrous oxide gas, under about 40 Ib. pressure, to the surface of the 

 melted gold, forcing it into the finest intricacies of the mold. The cast filling thus made is 

 cut free from the casting head or sprue, and its outer surface is finished with a fine polish; it 

 is then cemented to place in the tooth cavity with a suitable fine grained cement. The cast 

 metallic inlay, while not universally applicable in all classes of cavities, especially where the 

 color of gold would be objectionable on aesthetic grounds, has, however, a large usefulness in 

 restoration of molar teeth weakened by extensive caries and where great strength of material 

 is required to withstand the stress of mastication. The porcelain inlay has its special applica- 

 tion to the filling of cavities in exposed positions in the front teeth where the insertion of 

 gold restorations would be unsightly. The porcelain inlay is made by first forming a matrix 

 in platinum foil of extreme thinness (.001 of an inch) by burnishing the foil into contact with 

 the cavity walls and then filling the matrix thus made with porcelain paste and fusing it to 

 homogeneous mass. Any tint or texture may be thus produced, enabling the skilful operator 

 to imitate perfectly the texture and color of the tooth into which the inlay is to be inserted. 



While fillings of gold foil have for all time demonstrated their utility and trustworthiness 

 in the saving of carious teeth, gold has nevertheless distinct disadvantages for the purpose, 

 the recognition of which has constantly stimulated the search for an acceptable substitute 

 that would possess its valuable tooth-saying qualities without its objectionable feature of 

 color, high thermal and electric conductivity, and the difficulties of its manipulation. A 

 number of plastic substances, the amalgams, various cements and gutta percha, have been 

 in use for years, but each has been defective in certain qualities, and though used in large 

 quantity they have nevertheless had but a limited range of usefulness. Recently consider- 

 able advance has been made in connection with the plastic filling materials by the introduc- 

 tion of so-called silicate or silicated cements, combinations of calcium and zinc phosphate 

 with silica, which give promise of a decidedly nearer approach toward the long-sought ideal 

 plastic filling material. The peculiarly desirable feature of the silicated cements is their 

 translucency, which closely simulates that of tooth structure in appearance, and their high 



