Secondary imps - complete dentures lab

Question 1

What checks should be performed on special trays?

Answer 1

Perforated / non perforated?

Correct handle?

Stops in place?

Trimmed to 2mm short of full depth of sulcus? (allows room for border moulding material such as pink stick / green stick or heavy bodied silicone material – to flow into in order to pick up impression of functional sulcus ]

Question 2

What is the function of stops on special trays?

Answer 2

The stops hold the tray away from the model / tissues so that the impression material has got room to flow beneath the tray.

Otherwise material may get trapped in one area.

Allows material to act elastically if there are any undercuts that it needs to spring in and out of.

If technician hasn’t inserted them, can use green stick to add on 2-3mm in thickness and stuck to tray forming a triangle.

Question 3

Prior to border moulding, where is the greenstick placed on special trays?

Answer 3

1. Start by recording the post dam area, being careful not to extend the tray too far distally. Compress tissues along post dam line to create posterior seal.
2. Then place around the sides of tray to record the functional sulcus. Try to keep to outside of tray but if any gets onto inside, remove using hot wax knife.

Question 4

What is a good secondary impression?

Answer 4

Sulcus present
Rolled and rounded impression
Muscle attachments present
Back of impression: hamular notches obtained
Good surface detail
Labial frenum at fornt.

Question 5

Where are the lines drawn on the impression material for the technician?
[primary vs secondary imps]

Answer 5

Line drawn on outside 2mm from sulcus depth to guide technician when trimming model for secondary imps.

On inside for primary imps