Triple trays will celebrate a birthday this summer. It’s hard to believe it received its patent 35 years ago and more than 100 million have been sold. It’s clearly one of the most popular impression trays utilized today because of its simplicity in design, ease of use and low cost. It is curved to accommodate the arch form and the teeth and its thin pliable mesh allows it to adapt to various tooth relationships without deforming. The plastic sidewalls won’t deform on removal and these impressions are considered accurate and are preferred by most dental laboratories.
There is one clinical scenario that triple trays will not work well and if you can identify this before you start the impression process, you can eliminate the time and expense incurred for remaking one. If you have a tooth that is displaced to either the buccal or lingual even when prepared, you run the risk of the edge of the tray engaging your prepped tooth. If it does, the impression material will be distorted as it won’t accurately mold the tooth as the tray will be pushing against it. It may not look like it’s a problem but understand that it won’t be accurate. You can see in the photo where the edge of the red tray is evident but if you look even closer, you can see just the hint of the red tray within the shoulder portion of the prep.
If you see this, discard the impression and start over but remember for next time to use a different (stock) tray that you can modify to accommodate the tooth displacement and capture a great impression. If you encounter a problem with the seating of a crown check your triple tray impression to be sure there is no hint of tray impingement.
Mary Anne Salcetti, DDS, PC, Spear Visiting Faculty and Contributing Author. www.maryannesalcettidds.com