Dental cosmos . hows that vulcanizable rubber ex-pands when heated, and shrinks when cooled after says, There are then two shrinkages to be taken into accountin vulcanite,—one inherent to its production from the compound ofcrude India-rubber and sulphur; and another, in common with most FLASKING DENTURES FOR VULCANIZATION. 527 other substances, from changes of temperature. The two combinedare the secret of many of the annoyances experienced in makingvulcanite dental plates, from failure to secure proper adaptation. That whole subject will not at this time be discussed, but onl
Dental cosmos . hows that vulcanizable rubber ex-pands when heated, and shrinks when cooled after says, There are then two shrinkages to be taken into accountin vulcanite,—one inherent to its production from the compound ofcrude India-rubber and sulphur; and another, in common with most FLASKING DENTURES FOR VULCANIZATION. 527 other substances, from changes of temperature. The two combinedare the secret of many of the annoyances experienced in makingvulcanite dental plates, from failure to secure proper adaptation. That whole subject will not at this time be discussed, but only somepractical points presented in relation to flasking; and here it isnecessary to differ not only with Dr. Snow, but with most otherwriters and practitioners who have followed Dr. Wildman in makingradial grooves, or gates, for the outflow of the excess of gates are faulty in fact and in principle, whether made in themodel half of the flask as shown in Fig. 1, or in the teeth-half of the Fig. flask as seen in Fig. 2. The illustrations are taken from Wildmans Instructions in Vulcanite, published in 1875. The annular grooveshown in Fig. 2 is suggestive of the proper mode of providing areceptacle for the excess, but the radial gates really defeat the trueobjects in view by affording too free an escape of the softened rubber,thus preventing that condensation of the inclosed material which isnecessary for the production of the best results. It is more convenient to form the annular groove in the teeth-halfof the flask, but, for reasons which will presently be given, it is pref-erable to cut the groove in the model-half as is shown in Fig. 3. Thegroove should be ample in width and depth, and should be beveledfrom its bottom to within one-sixteenth of an inch of the gum and 528 THE DENTAL COSMOS. palatine (or lingual) border. The like surface next the flask shouldbe slightly and evenly scraped to bevel it towards the groove, so thatthe two parts of the flask will
Size: 1740px × 1437px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthor, bookcentury1800, bookdecade1880, booksubjectdentistry
