Impression Tools

Oto-Dams

All oto-dams work on the same basic principle. An oto-dam is manufactured to a specific diameter from a material that has an inherent resistance to reduction in diameter. As the oto-dam is placed in an ear, it is compressed by the canal walls. The resistance of the oto-dam to this compression, or what is called “radial pressure”, holds the oto-dam in place against the force of the impression material.

The two types of oto-dams in common use today are vented and non-vented.

Vented Oto-Dams
With any conventional oto-dam (foam or cotton), once the impression material has made full contact with the ear canal wall, any air trapped behind the dam is forced to compress against the eardrum.

This sensation of ear “fullness” can range from minimal to significant discomfort. A vented foam oto-dam allows for the equalization of air pressure
within the ear during the impression making, curing and removal process, which can significantly reduce discomfort.

Non-Vented Foam Oto-Dams
Non-vented foam oto-dams are available in a wide variety of sizes and are soft, comfortable, and easy to use. Size selection is the most common challenge in using a foam oto-dam. Be sure to choose the appropriate size for your patient, using visual inspection to ensure that it fits snugly in the ear canal.

Non-Vented Cotton Oto-Dams
Non-vented cotton oto-dams are soft, comfortable and function well. However, because of the manufacturing process, many cotton oto-dams are supplied as hard, compressed wads, so be sure to fluff the cotton oto-dam before use. The softer, more pliable the oto-dam, the more effectively and comfortably it will seal off the ear canal.

Impression Syringes

Historically, the syringe method has been used to take impressions of the human ear, offering clean, quick and precise control of the impression material as it enters the patient’s ear. Syringes are available in several designs to work with specific impression materials.

Impression Guns

Manual or electric impression guns effectively eliminate the guesswork associated with the mixing of materials through the use of dualchamber cartridges and special mixing tips.

The precise amounts of “A” and “B” components, propelled through the tip, insure proper mixing prior to delivery into the ear.