The recording bases have to be firmly seated on the casts. Do not press the maxillary recording base to seat the mandibular or visa versa. This will change your record.
After the bases are seated make sure that nothing interferes posteriorly. The models can't hit each other, or the recording base touch recording base or opposing master cast. Students are too casual in cutting the models when they hit each other. The most dangerous cut is in the hamular notch area. Students actually cut away the hamular notch that was so carefully captured in the impression. Get help or confine most of the cutting to the retromolar pad area. You can usually get the models to seat without ruining either model. I usually mark the point of contact with a pencil. Then I check where it is most convenient to remove stone.
If anything hits, the models will be kept apart posteriorly. The teeth will now be set hyper and when you do the try-in you will have a prematurity posteriorly.
The mandibular model should be notched and lubricated.
Your incisal guide pin will be slightly longer (than zero) and locked at that point. (If you don't have a space anteriorly the pin will be set on zero.)
Using a teaspoon of fast set plaster in slow set plaster will hasten the setting. You can use all fast set if you are comfortable with it.
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©1999 by Julius Rosen, D.D.S.