. Elementary and dental radiography / by Howard Riley Raper . h an illuminating boxwill enable one to observe the negative to the best possible advantage. The denser the part, the deeper will be the the Relative shadow thrown on the film, and. consequently, the Ualues of Dense more transparent the negative in that region. Thus Areas in negatives, in the negative, metal fillings, posts and metal crowns appear as transparent areas; gutta-percha, cement, 136 READING RADIOGRAPHS 13; enamel and porcelain a little less transparent; then in the order of theirrespective densities, dentin, bone, gum ti
. Elementary and dental radiography / by Howard Riley Raper . h an illuminating boxwill enable one to observe the negative to the best possible advantage. The denser the part, the deeper will be the the Relative shadow thrown on the film, and. consequently, the Ualues of Dense more transparent the negative in that region. Thus Areas in negatives, in the negative, metal fillings, posts and metal crowns appear as transparent areas; gutta-percha, cement, 136 READING RADIOGRAPHS 13; enamel and porcelain a little less transparent; then in the order of theirrespective densities, dentin, bone, gum tissue, and, last, the cheek appears—when it is shown in the negative at all—as the least transparent part,except that part of the negative on which the X-Rays have fallen directlywithout anything intervening except the black paper of the packet. Thecontrast between tooth and bone tissue is very marked. Unfilled canalsand pulp chambers appear as dark streaks and areas in the teeth. Filledcanals and pulp chambers appear light. Pulp stones appear as lighter. Fig. 123. An Illuminating Box. spots in the dark of the pulp canal or chamber. Abscess cavities appearis dark areas. It is easy to distinguish enamel from dentin, and the peri-dental membrane can clearly be seen as a dark streak following the out-line of roots. A bit of calculus in the peridental membrane will appearas a light spot. This calculus must be on either the mesial or distal sideof a root to be seen. It could not be radiographed if it occurred on thebuccal, or labial, or lingual. All the foregoing may be seen in good negatives,negatives, Prints but a^ tn*s cann°t be seen in prints and Ijalf-tone I recall distinctly having read an article on Dental Reproductions. Radiography in which the writer printed a half-tone and told his readers to observe the enamel, the den-tin and the peridental membrane. The writer of this article wrote his 138 DENTAL RADIOGRAPHY paper with either a negative or a good prin
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