GB761759A - Improvements in or relating to artificial teeth - Google Patents

Abstract

761,759. Artificial teeth. FISCHER, R. April 8, 1953 [April 19, 1952], No. 9539/53. Class 81(2) In apparatus for manufacturing artificial teeth an articulator in which premolar and molar teeth, each formed with at least one cusp or depression, are to be cut, has guides formed in such a way that the protusive movements, in their projection on the vertical anterioposterior sagittal plane, i.e. seen from the side, are inclined at an angle to the horizontal which differs from that of the lateral movements. Such guides are shown in Fig. 4 the conical guides 51, 59. 83, giving as shown in Figs. 15, 16, 17, an' angle of d when the upper and lower teeth move relatively from right to left or vice versa (i.e. protrusively) and an angle of B when the teeth move laterally. These angles can be seen to differ although the inclination of the conical surface is 20 degrees in every vertical plane through the centre of the conical depression. The explanation lies in the fact that the angles d and B are measured in. projection on a particular vertical plane, in this case the plane which coincides with the paper on which Figs. 15, 16, 17, are printed. Guides such as shown at 91, 101, 133, on Fig. 5, may also be used all guides being preferably such that all relative movements of upper and lower premolar and molar teeth when set in the mouth are at 20 degrees inclination to the horizontal. Figs. 7 and 8 show an example of this, the band 66 of the tooth 67 being at 40-45 degrees inclination whilst the two bands 65, 68 are at 20 degrees inclination. Fig. 11 shows the tooth block of 67 before the tooth facets are cut whilst Fig. 13 illustrate how teeth cut with such facets interconnect. Various shaped cusps and depressions are shown and described in the Specification, all being such that the inclination of movement of facet relative to facet is about 20 degrees to the horizontal, this inclination being the one which is stated to be such that in the three directions of movement for the protrusive and lateral movements, left and right, the friction taking place between the articulation surfaces, which friction tends to move the teeth from their positions relative to the upper and lower jaws, is compensated by the relative rise of one surface to the other when the surfaces are moving to the point of central occlusion, and consequently the teeth do not move relative to their respective jaws. Fig. 30 shows how the teeth are marked. Each of the first premolars 321. 344, and the first molars 327, 338, has only one bead 323, 342, 329, 336, each of the second premolars 324, 341, and the second molars 330, 335, has two beads 326, 339, 332, 333. In the upper teeth the beads do not extend beyond the median line whereas the beads in the lower teeth extend beyond the median lines 343, 340, 337, 334. Specification 249,089 [Class 81(ii)] is referred to.