When adding a tooth or clasp to an existing partial, a pickup impression is required. Make sure the appliance is fully seated in the patients mouth. Then, using alginate impression material, take an impression of the arch. The appliance should come out inside the impression.
We ask that you do not pour up pick up impressions. If you decide to pour it up, please don't use a vibrator. Start with stone on one side and lightly tap the impression on the corner of the table, turning it as you go to avoid bubbles. The vibrator often results in stone getting under the appliance, rendering the impression innaccurate.