A practical treatise on artificial crown- and bridge-work . ine of the margin of the gum, withthe palatal portion projecting slightly above it, to include a littleof the cervix. The cavity in theporcelain is given a size, form,and position which will receivethe posts extending from the capwithout impairing the strengthof the crown-walls. Thus theyare made round in the incisorsand cuspids (A, Fig. 257), oval inthe bicuspids (A, Fig. 258), and following the curve of the lineof the posts in the molars.^ 1 The form of porcelain crown described is also used by Dr. Perry withoutcapping the root, sim
A practical treatise on artificial crown- and bridge-work . ine of the margin of the gum, withthe palatal portion projecting slightly above it, to include a littleof the cervix. The cavity in theporcelain is given a size, form,and position which will receivethe posts extending from the capwithout impairing the strengthof the crown-walls. Thus theyare made round in the incisorsand cuspids (A, Fig. 257), oval inthe bicuspids (A, Fig. 258), and following the curve of the lineof the posts in the molars.^ 1 The form of porcelain crown described is also used by Dr. Perry withoutcapping the root, similarly to the Howland crown. In such cases he usuallyprotects the end of the root either with a surface of condensed gold foil anchoredin a reamed cavity formed around the ^wst in the root-canal, or Avith a very thindisk of gutta-percha. The disk with the aid of heat or chloroform- is made toform a line of union between the root and crown. In both methods oxyphos-phate is used in the cavity which receives the post to attach the crown. Fig. 257. Fig. THE PERRV CROWN. 129 A suitable crown (C, Fig. 256) having been selected, it is groundand fitted in proper position on the cap. This operation is facili-tated l)y perforating a disk of marking-paper with the posts andadjusting it on the cap. Then, as tlie crown is placed on the capand pressed against it, points which prevent perfect adjustmentare marked on the porcelain. By this means a close joint iseasily secured. The edge of the porcelain should be fitted underthe free margin of the gum, especially at the cervico-palatalpart. The porcelain crown is next set over the projecting pins,and cemented to the cap with oxyphosphate. The advantage of this method is, that the root being slightlytapered, the collar can be made to fit absolutely, while theexcess of oxyphosphate is gotten rid of through the vent-holes,instead of being squeezed out around the edge of the edge of the collar being made to a knife-edge, can bepro
Size: 1965px × 1271px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectcrowns, bookyear1889
