An atlas of skiagrams : illustrating the development of the teeth with explanatory text / by Johnson Symington and J. C. Rankin.
- Symington, Johnson, 1851-1924.
- Date:
- 1908
Licence: In copyright
Credit: An atlas of skiagrams : illustrating the development of the teeth with explanatory text / by Johnson Symington and J. C. Rankin. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
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![INTRODUCTION At the Annual Meeting' of the British Dental Association held in Belfast last -lune we exhibited a series of skiagrams to illustrate certain stages in the development of the teeth in man. The favouraljle opinion which was then expressed as to the scientific interest and practical value of these skiagrams has induced us to reproduce and publish them in a collected form. Since the discovery in 1895 by Pi'ofessor Rontgen of the peculiar properties of the emanations from the antikathode of a vacuum tube, these so-called X-ra\'s have freijuently been used to obtain skiagrams of teeth in the living subject for diagnostic pur])oses and as an aid to treatment, but hitherto no systematic attempt a])|)('ars to have been made to examine by this agency the position and relations of all the teeth during their development from infancy to adult life In this investigation the head was divided in the median plane, and as a rule the soft parts in the region of the jaws, except the gums, were removed. E;ich half was then placed with its lateral aspect upon a photograpliie ])late which was enclosed as usual in light-proof envelopes. It was found that when the rays were directed downwards u])on the specimen with its median cut surface in a horizontal plane, the shadows cast b\' the central and lateral incisors were apt to nearly coincide with one another, so that their individual form could not satisfactorily be distinguished. Accordingly the posterior ])art of the skull was raised about 30° above the horizontal plane, by which means this overlapping of the shadows of the teeth at the anterior part of the dental arch was to a considerable extent avoided, and all the teeth on one side of the median plane were projectdl separately on to the photographic plate. In some cases the greater part of the skull was removed in order to bring the jaws as close as possible to the plate, since the shadows of the teeth are then more sharply defined. In nearly all the skiagrams the upper teeth are less distinctly seen than the lower. This is due to the shadow of the hard palate crossing these teeth, and also to the prominences of the malar and of the frontal bone, which interfere with the close approximation of the uj^per dental arch to the photographic plate. The antikathode was fixed about nine inches above the photographic plate, imperial](https://iiif.wellcomecollection.org/image/b21458868_0011.jp2/full/800%2C/0/default.jpg)
