Which tool is specifically used to remove air bubbles from impression material?

The tool that is specifically used to remove air bubbles from impression material is a vibrator. The function of a vibrator in dental practice is to ensure that impression materials are evenly and thoroughly seated against the teeth and surrounding tissues without the presence of air pockets, which can compromise the accuracy of the impression. When the impression material is poured into a tray or while it's being manipulated, using a vibrator helps to displace trapped air and allows the material to flow more uniformly, ensuring a detailed and precise impression.

The other tools mentioned serve different purposes: bite/wax wafers are used to make occlusal registrations, a laboratory knife is utilized for cutting and trimming materials in the lab, and a plaster spatula is typically used to mix dental materials rather than to engage with impression materials directly. Understanding the specific functions of these tools highlights the importance of using the correct instrument for the task to achieve optimal results in dental procedures.