A Problem-Solving Impression Technique

(Continued)

7. The patient was asked to close his mouth firmly. Once the material was set, the patient was asked to open his mouth, and the tray was completely removed. Visual inspection revealed the wash material had successfully duplicated the prepared margins (Fig. 9). A defect on the second premolar and the beginning of furcation involvement on the second molar were also clearly visible in the impression (Fig. 9). A periapical radiograph shows the mesial defect on the second premolar (Fig. 10).

Figure 9. The impression is removed from the mouth and visually inspected for completeness Note the reproduction of the mesial second premolar defect and the furcation detail on the molar.

Figure 10. Radiograph of the working site. The mesial defect on the second premolar was also evident in the wash impression.

8. Individual master stone dies show excellent reproduction of the prepared margins (Fig. 11). Subsequently, a metal framework was fabricated from an articulated working model (Fig. 12). The patient returned to try-in the metal framework, and an interoccusal record was taken with the framework in place. The prosthesis was remounted and finished to completion.

Figure 11. Individual stone dies exhibiting excellent reproduction of the prepared margins.

Figure 12. The articulated working model.

Discussion

A dual-arch impression of the prepared teeth was taken using a base material delivered in a half-arch plastic gauze tray.

The base material chosen for this case exhibited a hard, plaster-like set that resists hydraulic pressure, minimizing distortions under pressure. This is attributed to a high Shore A Durometer measurement of 75 and the filler content of the impression material. When set, the impression was disengaged from the prepared teeth and allowed to remain on the opposing dentition. The wash material was syringed onto the impression of the prepared teeth without removing the impression tray from the mouth. The patient was instructed to bite firmly onto the wash material, thereby hydraulically forcing the wash material into place. The wash material specifications showed a lower Shore A Durometer measurement of 40 and set to a flexible state. When set, the impression was removed from the mouth showing a detailed one-half arch impression of the prepared teeth and a simultaneous impression of the opposing dentition in centric occlusion. The patient perceived the technique as faster than previous impression-taking experiences, and without discomfort or gagging.

Clinically, the technique yielded convenient material placement, no waste of material, and accurate results. If corrections were needed, the wash impression could be repeated, as the polyvinyl siloxane material would allow lamination to itself.

The selected materials were key factors in producing distortion-free impressions using a two-step, dual-arch technique that maximized patient comfort in this clinical situation.

Dr. Hoos maintains a private group practice in Stratford, CT. with a special interest in cosmetic, reconstructive, and implant dentistry. Dr. Hoos conducts continuing education seminars on topics of practice management and reconstructive implant dentistry.

For technical information, call (800) 818-7788.

To order call (800) 752-9720.

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