When to use a triple tray impression:
- When the filament between the upper and lower teeth will cause slight distortion in the occlusal morphology of the unprepared teeth, and may cause a slight shift in the occlusion when biting into the impression material.
- When the accuracy of the bite is sometimes difficult to confirm. This is why a bite registration is suggested over the prepared tooth.
- When the articulation used does not represent the normal distance from the condyles to the restorations fabricated. This means that only the intercuspal contacts (MIP) can be checked in the laboratory. No lateral or protrusive movements made on these simple hinge articulators will replicate nature. At the time of insertion, there is a greater need to check and adjust centric and eccentric contacts when compared to full arch casts mounted on a semi-adjustable articulator.
- When teeth on the contralateral side are not impressed, so the tooth morphology produced in the restoration will not match to these teeth. As long as you understand the limitations of using a triple tray technique, it can create an acceptable outcome for simple posterior cases.