What is a heifer cow? A heifer is a mature female cow that has not calved, or given birth to a calf, yet. As soon as a heifer gives birth, she becomes a cow. A cow refers to a female of any age that has given birth.
When most people think about gas masks or respirators, what they usually envision is a tight-fitting plastic or rubber face mask with some sort of filter cartridge. The mask covers the nose and mouth. These are called half-mask air-purifying respirators.
The patient is able to drive and resume normal activities immediately following the dental visit. Nitrous oxide (also called laughing gas). This gas, which is inhaled by the patient through a rubber face mask, helps people feel relaxed and is one of the most common forms of sedation used in the dental office. Effects wear off quickly after the gas is turned off.