Air entrapment in impressions is when there are pockets of air within the impression material which distort the accuracy of the impression.
Air entrapment in impressions can be caused;
- When dispensing the material, if you're not careful.
- If you lift the tip of the gun while dispensing.
- Inadequate preparation of impression material
Try the following actions to prevent air entrapment in impressions:
- Cleaning the teeth and gum tissue before impressing to remove plaque, fluid, and other buildup creates a clean slate for the PVS material.
- Also, if you've already taken multiple impressions on the same patient in one sitting, be sure to clean the teeth before re-impressing each time. This improves detail and prevents air entrapment.
- To prevent air entrapment, keep the tip of the gun down and dispense the material evenly, as demonstrated in this tutorial and video.
- Seat the tray gradually from anterior to posterior or vice versa depending on your preferred technique to allow air to escape as the tray is being seated.