A Preliminary Survey of Impression Trays Used in the Fabrication of Fixed Indirect Restorations

Purpose: A variety of impression trays are used in the fabrication of fixed indirect restorations. Impressions used in the construction of fixed indirect restorations were examined for tray type, manner of use, and overall impression quality.
Materials and Methods: A commercial dental laboratory provided 1403 impressions used to fabricate fixed indirect restorations during a 3-month period. Impressions were examined for tray type, quantity and type of recorded abutments, the impression of intact teeth adjacent to and opposing the abutment, the presence of the canine in the impression, and an assessment of the quality of the impression.
Results: A majority of trays examined were plastic (864, or 61.6%). Dual-arch trays comprised 73.1% of the total. Most of these were metal posterior (n = 499) or plastic posterior (n = 280). Among partial dual-arch impressions, 561 (55.7%) were for the single abutment restoration, bounded by intact teeth anterior and posterior, and with an intact opposing tooth. Eleven percent of plastic dual-arch impressions failed to register the canine. Regarding restoration type, there were 955 impressions for the single-tooth crown, 46 for implant-supported restorations, and 11 for veneers. Twenty impressions were for posts, inlays, or onlays. Impressions for multiple single-tooth crowns and fixed partial dentures comprised the remainder. In terms of overall quality, 85.3% of impressions were excellent or good. The lowest performance in terms of excellent quality was in the anterior plastic single-arch impression (44.8%), whereas the best rate of excellent quality noted was for the posterior dual-arch impression (82.4%).
Conclusions: Within the limitations of this study, dual-arch trays were the most commonly used tray. Recommendations for the use of the dual-arch tray were not followed in a substantial number of impressions examined.