Inhaled minimal sedation:
You breathe nitrous oxide: otherwise known as "laughing gas" -- combined with oxygen through a mask that's placed over your nose. The gas helps you relax. Your dentist can control the amount of sedation you receive, and the gas tends to wear off quickly. This is the only form of sedation where you may be able to drive yourself home after the procedure.
Oral sedation: Depending on the total dose given, oral sedation can range from minimal to moderate. For minimal sedation, you take a pill. Typically, the pill is Halcion, which is a member of the same drug family as Valium, and it's usually taken about an hour before the procedure. The pill will make you drowsy, although you'll still be awake. A larger dose may be given to produce moderate sedation. This is the type of anesthesia most commonly associated with sedation dentistry. Some people become groggy enough from moderate oral sedation to actually fall asleep during the procedure. They usually can, though, be awakened with a gentle shake.
IV moderate sedation: You receive the sedative drug through a vein, so it goes to work more quickly. This method allows the dentist to continually adjust the level of sedation.
Deep sedation and general anesthesia: You will get medications that will make you either almost unconscious or totally unconscious -- deeply asleep -- during the procedure. While you are under general anesthesia, you cannot easily be awakened until the effects of the anesthesia wear off or are reversed with medication.