When they sedate you @ the dentist, what is the stuff that they inject into your body after they put the mask?

I just had all four wisdom teeth removed a few hours ago and the gave me laughing gas (nitrous oxide) and oxygen through the mask. Then they started me on an IV of Versed and some type of steroid to reduce swelling. They also injected novacaine into my gums to numb my mouth. This was just my experience but I hope it helps.