Clinical Technique

The following technique includes all the requisite steps required to produce maxillary and mandibular definitive impressions of the edentulous arches in a manner that will permit the application of CAD/CAM technology.

The overall goal is to make definitive edentulous impressions that capture the edentulous ridges and borders (vestibules) while recording as much as possible of the functional soft tissue that will be in contact with the facial surfaces of the denture bases located occlusal to the denture borders. Additionally, the impressions should record muscular and phonetic positions suitable for placing prosthetic denture teeth.

Impression trays

The edentulous impressions can be made by using either a custom tray (Fig. 1A) or a stock tray that can be molded to conform to the shape of each patient's arch and provide the required border extensions.

Fig. 1. A, Custom acrylic resin mandibular impression tray. Tray handle is fabricated so it extends vertically from anterior ridge crest and then turns anteriorly to pass through lips with minimal interference with oral musculature. B, Maxillary and mandibular moldable stock trays. C, Maxillary tray was softened in hot water and intraorally molded to fit edentulous maxilla form. It was then border molded and coated with vinyl polysiloxane adhesive in preparation for definitive maxillary impression.

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Newly designed thermoplastic stock trays (Vident, Brea, Calif) (Fig. 1B), specifically designed for edentulous patients, have been developed by Dr Stephen Wagner. They are advantageous for this technique as the trays can be adapted to the shape of the edentulous arch by softening each tray in an 80°C (180°F) water bath for 1 minute (no tempering needed) and then adapting it intraorally to fit the specific contours of each patient's edentulous arch. In the softened state, the tray borders can be trimmed with scissors if the extensions need to be shortened. Likewise, the softened material can be stretched or added to when the tray needs to be extended to reach desired landmarks. After the tray has been customized to fit the arch, only the borders are softened, and the patient's musculature is activated to mold the softened borders (Fig. 1C).