Processing acrylic resin bases for removable partial dentures on a hydrocolloid cast

Abstract

P a n t o g r a p h t r a n s f e r o f t e r m i n a l h i n g e a x i s , e f f e c t s o n o c c l u s a l m o r p h o l o g y M. J. Jaarda, ]. A. Clayton, and G. E. Myers University of Michigan, Ann Arbor, Mich. The importance of the terminal hinge axis (THA) in pantography has been viewed as a basic assumption, but the significance and effect is unproven with only limited research. Previous studies have indicated that the transference of the THA does affect articulator settings, however, the effect on occlusai morphology has not been sufficiently shown. Instrumentation was developed whereby ridge and direction and cusp height could be measured in the form of co-ordinates of an x-y-z co-ordinate system. The instrumentation consisted basically of a precision linear variable differential transformer (LVDT) that could be rotated through all three Reprinted from the Journal of Dental Research with permission of the author and editor. planes and mounted within the first molar area on a Denar D5A articulator. Two subjects were investi- gated by means of pantographic surveys performed relative to the THA. This was repeated with the survey relative to the arbitrary hinge axis (AHA). The DSA articulator was correspondingly programmed and the LVDT mounted in the maxillary first molar area. Cusp height and ridge and groove directions were then measured respective to each pantograph survey. The measuring error of the entire procedure was + .05 mm. along any given axis of the coordinate system. Statistical difference (p = .05) was shown for ridge and groove and cusp height. Magnitude of the difference was .2 mm. in protrusive excursion and .1 mm. in lateral excursion at the edge to edge position. 696 JUNE 1978 VOLUME 39 NUMBER 6