Columbia University School of Dental and Oral Surgery - Dental Columbian Yearbook (New York, NY)

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HOUGHTON HOLLIDAV A.B., D.D.S. Associate Dean and Professor of Dentistry RADIOLOGIC EVALD LIXDER Technician HARRY M. Ml ' LHAL ' S Technician The Radiology Division has been interested during the present year in designing, constructing, and testing a Laminograph. A Laminograph (lamina: thin layer) is a device by which plane sections of solid objects may be projected roentgenographical- ly; in other words, the roentgenographic shadow of a selected plane in a body remains stationary on a moving film, while the shadows of all other planes have a relative displacement on the film, and are therefore blurred according to their distance from the selected plane. This result is obtained by moving the point of origin of the x-rays and the recording medium or film. The x-ray tube and the film carriage move in synchronism in parallel planes and the patient is placed on a table over the film carriage. The principle of the Laminograph was worked out and a device patented bv Mr. Jean Kieffer of Norwich, Conn., in 1929. However, the device is complicated and expensive, and for many years no clinical use was made of it. In recent years it has been used extensively in pulmonary studies and it is thought that it may make it possible to detect active tuberculosis much earlier. Workers in some other fields have felt that they were unsuccessful in accomplishing anything clinically that could not be equally well done with the standard roentgeno- graphic procedures. It seemed possible that the principle might be successfully applied in studying the temporomandibular articulation. Accordingly the construction of an experimental apparatus was undertaken in the school machine shop. In brief, the apparatus consists of an oil im- mersed x-ray tube and transformer head and a film holder mounted about three feet apart, revolving in horizontal planes while the film is being exposed to the x-rays. The patient ' s head is interposed slightly above the film carrier on an adjustable table, bringing the temporomandibular articula- tion into the plane which remains stationary on the moving film. Limitations of space and time have interfered with the testing of the apparatus, and we are not vet prepared to say whether or not it will give diagnostic information of any greater import than that obtained bv ordinary methods. It is hoped that it may be possible to secure a clear image of structures which would otherwise be obscured by dense overlying or un- derlying tissue because the superimposed shadows would be blurred bv motion of the film and the x-ray tube. HOLGHTON HOLLIDAV, D.D.S.

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OR THODONTICS It lias been established by previous investigations that the influence of orthodontic treatment is not confined to the alveolar process but ex- tends to other parts of the skull, e.g. the mandibular condyle, the glenoid fossa, the ramus and the body and the angle of the mandible. Judicious control of such bone changes which are produced by different orthodontic means seems essential to the obtaining of favorable esthetic results from the treatment of many malocclusions. Thus, Orthodontic procedure develops into orthopedics or, more specifically, orthognatics. Clinical observation and the experimental findings of several authors justify the assumption that the vertical dimension cannot be increased permanently by ordinary orthodontic procedure but is constant in a given individual at a certain stage of development. This distance is probably the result of a balance between the length of the masticatory muscles and the bone. (Since the length of muscles is orthodontically practically unalterable, permanent increase of the vertical dimension cannot be attained by such means.) Proceeding from this basic knowl- edge we may attempt to produce permanent changes in the bony parts of the masticatory apparatus via intermediate changes in the vertical dimension. If we, for instance, raise the bite in one region or another, corresponding bone changes will take place, demonstrating nature ' s intention eventually to reestablish the original vertical dimension. While the depression of the teeth alone would be of slight benefit, and then only in a limited number of cases, the other bone changes leading to the final reestablishment of the original vertical dimension may be of great desirability in the correction of malocclusions and abnormal facial contours. It is the ability to control conscientiously these described bone changes which we hope to attain. LEUMAN M. WAUCH, D.D.S. LEUMAN M. WATCH, D.D.S. Professor oj Dentistry (t toi GEORGE S. CALLOWAY DOS. Associate Prof, of Dentistry m jA HARRY A. GALTON D.D.S. Instructor in Dentistry LEWIS E [ACKSON HENRY U. BARBER, Jr. EDWARD G. MURPHY ARTHUR C. TOTTEN DONALD B. WAI (.11 D.D.S. D.D.S. D.D.S. D.D.S. D.D.S. Instructor in Dentistry Assistant Prof, of Dentistry Assistant Prof, of Dentistry Assistant Prof, of Dentistry Instructor in Dentistry

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CHARLES F. BODECK.ER DTJ.S. Professor of Dentistry EDMUND APPLEBAUM D.D.S. Assistant Prof, of Dentistry The importance of the application of the knowl- edge of oral histology to the clinical branches of dentistry is increasing, as is evidenced by the re- sults of recent experimentation in operative den- tistry. Studies of the dental lymph have shown that the presence or absence of this fluid affects the marginal areas of cavities, particularly if the fillings had been placed early in life. The varying per- meability of the teeth of young and old persons is also related to the dental lymph. Permeability is a factor in the activity of dental caries; in older persons the low permeability of the tooth crowns retards the penetration of the destructive process, while high permeability of the permanent teeth of children and adolescents permits rapid destruction. Vital staining of teeth of dogs shows that the enamel as well as the dentin is completely permea- ble to dyes placed in the pulp. Human deciduous teeth treated similarly show that the dental lymph carries dyes through the dentin to the inner zone of the enamel. A two way diffusion in the dentin has been demonstrated. These observations sug- gest that the lymph serves some definite purpose tik Ltin WILLIAM LEFK.OWITZ D.D.S. Assl. Prof, of Dentistry KFRNERD THOU S D.D.S. Instructor in Dentistry ORAL HISTOLOGT in the recently erupted tooth and studies concern- ing the possible physiological activity of this fluid are being continued. The permeability of freshly cut. non-carious den- tin in relation to phenol has been studied. It was observed that this drug penetrates from a shallow cavity to the pulp in 18 hours. The present state of the experiments does not indicate that phenol is contraindicated for cavity sterilization because the permeability of the dentin is usually reduced under caries by a blocking of the tubules through metamorphosis of the dental lymph. The use of phenol may be harmful because of its rapid, easy penetration of the open, lymph-filled tubules. Studies in the Division of Dentistry for Children suggest that apparently phenol does not permanent- ly harm the dental pulp of deciduous teeth: in fact, it seems beneficial in stimulating the formation of secondary dentin. The effects on rats of a disturbed acid-base bal- ance as a possible factor in dental caries is also be- ing studied. CHARLES F. BODECKER, D.D.S. ORAL ANATOMT MOSES DIAMOND D.D.S. Associate Prof, of Dentistry JACOB ERDREICH D.M.D. Assistant in Dentistry ROBERT N. HOFFMAN D.D.S. Assistant in Dentistry