When is a custom impression tray indicated?

• A. Only digital impressions used
• B. For all impressions
• C. When stock trays fail to capture fine detail or tissue dampness
• D. When using alginate alone

Answer: (C)

Custom impression trays are used when the stock tray can’t achieve the needed accuracy. They are shaped to fit the patient’s arch closely, creating a uniform space for the impression material. This helps capture fine details like margins and sulcular tissue more reliably and also helps manage moisture by reducing distortion from damp tissues. In straightforward cases where the stock tray fits well and the tissues aren’t a moisture problem, a custom tray isn’t necessary. Digital impressions or simple alginate impressions with an appropriate stock tray don’t routinely require a custom tray.