Implant Specialist Alex Rugh, CDT explains why you may not want to use the cap that comes with the Straumann closed-tray impression copings. If you do want to use the cap, Alex explains what precautions to take.
What are the caps for?
The purpose of the cap is to provide a solid seat when placing the impression coping back in to the impression.
Are they necessary?
No, they are not necessary. The Straumann impression copings can be used with or without the plastic caps. If you do use the cap, handle it gently to avoid damage. Use only medium or heavy body impression material to help keep the cap from moving when the tray is pulled.
Should they be used?
We suggest that you do not use the plastic caps. We have found that sometimes the cap can prevent the impression coping from seating completely. This can happen from the cap shifting when the impression is pulled or from other damage that may have occurred to the walls of the cap. When the cap is damaged or has shifted, it can prevent the impression coping from correctly re-seating.
A question I get often is if it’s OK to use a Straumann impression coping without the snap on cap. And for reference, each closed tray impression coping from Straumann comes with two of these little caps that snap on to the top of the impression coping.
And my answer is no, you do not need to use these caps and in fact from my experience it’s actually better not to use them. Seemingly, the purpose of the cap is to provide a solid seat when placing the impression coping back in to the impression. But, what we have found however is that sometimes that cap actually prevents the impression coping from seating completely.
And there are a couple of ways that can happen; The first is that the cap can shift slightly when the tray is pulled. This can cause the walls of the plastic cap not to line up completely with the rest of the impression. So when the impression coping is re-inserted in the impression, it hits the top of the cap wall and it feels like it’s seated.
The second is that the walls of the cap can be damaged at some point before or during the impression. Those walls are pretty thin and can easily be deformed which can again lead to an issue where the impression coping gets hung up by the plastic instead of seating completely in to the cap.
If you do want to use the cap, just be gentle when snapping it on to the impression coping to avoid deforming the plastic. I also recommend not using any wash material with these caps. Medium and heavy body impression material will do a much better job of preventing the cap from moving when the tray is pulled.