Preventing air entrapment in impressions

In light of our recent tech tip, Dr. Rick Gennaro sent in a great tip from an experience reviewing problematic impressions in a friend's lab:

I was shocked to see how poor the majority of impressions were. Improper tray selection, re-seating the tray, combining unrelated materials (i.e. PVS with polyether), inconsistent mixing, air entrapment, etc., all contribute to the problem.

A lot of what I saw, aside from inadequate preps and poor tissue control, was a simple issue of not having cleaned off the teeth and tissues, leaving behind debris and fluid. Unclear details and air bubbles were prevalent, and this was from several dentists. Cleaning with peroxide and washing would have helped greatly.

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. 

Air entrapment can also occur when dispensing the material, if you're not careful.  If you lift the tip of the gun while dispensing, it can create pockets of air within the material that distort the accuracy of the impression. To prevent air entrapment, keep the tip of the gun down and dispense the material evenly, as Dr. Pumphrey demonstrates in this video.

Thanks for the tip, Dr. Gennaro! How do you achieve the best results with your impressions? Share your own experience in the comments section below.

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