These earmold impression systems combine automatic mixing delivery devices with free-flowing, highly accurate, dimensionally stable silicone impression materials. They take impressions quickly and easily, and for many people, with consistent, uniform results. The disposable tips provide ideal mixing, in-the-canal delivery and mess-free clean-up. The finished impressions will not change with time or shipping conditions. Since the viscosities and set-up times are preset, these materials have the potential for high quality impressions each time they are used.
Some cautions, however, need to be included here. Some materials are quite runny when they are extruded from the tip, and can be hard to manage in the ear. Specifically, it can be difficult to know that you are getting material where you want it because it is so liquid. While the material doesn't sag as such, it can cling to the tip and hide an area that needs to be filled. Voids can occur and are not necessarily evident until the impression is removed.
In addition, the gun is difficult to use for people who lack hand strength, because the trigger must be pulled through a complete cycle before it can cycle to the next tooth on the plunger. Women with small hands often have trouble with the cartridge-gun systems, and as stated earlier, earmold labs consistently report that impressions made with the guns are not as good overall as those made with syringes.
The cartridge-gun systems are rather straightforward in their use, however. With the plunger all the way back, a cartridge is inserted in the gun and the retainer locked down. The plunger is then set at the back of the cylinders of the cartridge. The appropriate size tip is then installed on the front of the cartridge. Squeeze out about ¾" to 1-1/2" of material to insure proper mixing, and then make the impression, which should be complete within 30 seconds of the test squeeze.
After 3 – 5 minutes, depending on the material, test the outer surface of the silicone by indenting or scratching it. A fingernail is fine for this purpose. If the material does not retain the indentation, it is ready to be removed.