Making Midsagittal diagrams

In order to obtain a precise diagram of the shape of the speaker's palate, the palatal impression must be accurately sectioned in three dimensions. The first cut will be through the center of the impression to provide an datum line for further measurement. To get the most information on the shape of the soft tissues, the impression should be cut mid-sagittally before trimming around the teeth (Fig.7). Next trace an outline of the palate, upper teeth, and upper lip on a sheet of paper (Fig. 8). Use a ruler and your fingers to brace the impression (Fig. 9).    Alternatively, put one of the halves on the glass of a copy machine, and copy.  Either way, make several copies of the tracing just in case. 
 

Fig 7: The impression is now sectioned along the saggital plane. Use the central fissure as a guide.	Fig 8: One of the resulting halves is used as a pattern to create a paper tracing.
Fig 9: The flexible nature of the alginate requires careful support so as not to distort the shape of the palate.

         Next, bisect the impression halves in the coronal plane, at a point about the middle of the impression (usually between the second premolar and first molar). The intersection of these mid-sagittal and coronal cuts can be used to define x and y axes and an origin on a piece of graph paper.