Methods and devices utilizing rheological materials

An impression device for making an impression of a desired feature, the impression device comprising:

• a flexible bladder bite bag having a cavity formed therein, the flexible bladder being conformable to a feature in a person's mouth as the desired feature;
• a magneto-rheological material disposed in the cavity of the flexible bladder;
• and
• a magnet for generating a magnetic field in at least a portion of the magneto-rheological fluid and capturing an impression of the desired feature thereby, wherein the magnet further comprises a u-shaped magnet having first and second ends adapted to be disposed between teeth in the person's mouth and an inner surface of a cheek.