Preliminary impression for maxillary defect: A two-step technique.

Preliminary impressions must record the periphery and height of maxillary defects to allow for an eventual extension of the master impression tray. These impressions are usually made with irreversible hydrocolloid. Carrying the impression material into the defect can be complex, especially in the case of a limited oral opening. Moreover, the patient can be harmed during the removal procedure, and material may be stuck in anatomical structures. The technique presented in this article avoids these issues in any maxillary defect with a two-step preliminary impression. An elastomeric material ball is first placed in the defect until full setting. Then, this "obturator bulb" is removed and eventually relined until it is retentive. Retentions are designed on the oral side of the bulb and the bulb is placed back into the defect. Finally, an alginate over-impression of the maxillary is made. The alginate is removed after full setting, and the obturator can be reassembled on the maxillary impression to provide a full recording of the maxillary. This protocol can safely be used for defects of any size, despite eventual limitations in oral opening.