have been in use for single crowns since 1980 (1) and are used to make simultaneous impressions of a prepared tooth and the opposing teeth.
The assistant then immediately hands the triple tray to the dentist, who places the tray intra-orally over the previously dried teeth.
Prior to filling the initial triple tray impression to reline it, the assistant would have ensured that the patient could close completely into the tray, when the assistant was trying in the tray when making the provisional restoration.
After the dentist places the triple tray with the reline material in the mouth, the patient should occlude into the tray until the excess, leftover impression material on the desktop has set hard.
Prior to the dentist making the second reline, the assistant re-trims the triple tray impression as needed to ensure that the patient can occlude fully into it.
The authors suggest that an assistant only uses fast--setting (two minute set) impression materials with triple tray impressions.
Whether to use one triple tray versus two separate arch impressions
Before taking the pre-operative impression, the assistant decides if a triple tray impression can be used for the crown and bridge procedure being performed on the patient, or if instead two separate maxillary and mandibular arch impressions should be made.
A triple tray is acceptable to use if, after the tooth or teeth are prepared into abutments, it is still obvious, from the occlusion of the unprepared teeth, how to articulate the teeth together.