In Dentistry
A dental dam (sometimes known as a "Kofferdam"--from German), is used mainly in endodontic treatment and when putting fillings into teeth. They are thin squares of latex rubber. Silicone versions are available for those with latex allergies.
The main function is to isolate the tooth being treated from its environment, in particular from the bacteria in the oral cavity. The rubber dam is held over individual teeth or groups of teeth by appropriate rubber dam clamps or threads (ligatures) along the edge of the gum. The tooth crown stands out from the rubber dam through individual holes made by a hole punch. This permits a clean and dry operative field, retracts the lips and cheeks, and enables treatment of the appropriate tooth without contamination from blood or saliva. Another function of the rubber dam is to protect the patient's airway from any materials which may fall into it during treatment.
Routine use of dental dams is not always appropriate because of some difficulties: for instance communication with the patient is significantly reduced and the patient may feel restricted. However for endodontic procedures it is considered mandatory. For adhesive dentistry procedures involving bonding dental composite it is to be encouraged as the operative field must avoid moisture contamination in order to get maximum bond strength from restorative material to tooth substance. Glass ionomer cement is affected by moisture during its setting reaction and thus a rubber dam is considered advisable during placement.
Read more about this topic: Dental Dam