How are nitrous oxide and oxygen usually delivered during dental procedures?

Nitrous oxide and oxygen are typically delivered through a nasal mask during dental procedures. This method allows for a non-invasive way to administer the gases directly to the patient. The nasal mask is fitted over the patient's nose, allowing them to breathe in the mixture of nitrous oxide and oxygen comfortably. This delivery system enables the healthcare provider to easily adjust the mixture based on the patient’s needs and response throughout the procedure.

This approach is beneficial as it provides quick onset of sedation, and patients remain conscious and able to cooperate while experiencing a reduced level of anxiety. The use of a nasal mask also ensures that the patient's airway remains open and unobstructed, facilitating normal breathing.

The other methods mentioned are not suitable for delivering nitrous oxide and oxygen during dental work. Intravenous injection is used for different types of sedation and anesthesia but is not the standard for nitrous oxide. An oral tube is not practical for this purpose, as it would interfere with the dental procedure. Subcutaneous injection is not applicable here since nitrous oxide is a gas and must be inhaled to take effect.