The type of pain relief you'll receive for a dental procedure is proportionate to the actual procedure, with your own tolerances also taken into account. For example, a particularly anxious patient may need a mild form of sedation for their time in the dentist's chair, while another patient may only need a local anesthetic for the exact same procedure. If your upcoming appointment involves sedation dentistry, do you need to make any preparations?
When only light sedation is needed, nitrous oxide (also known as laughing gas) is often the go-to method. A mask is placed over your face, you breathe naturally, and the gas is absorbed via your lungs. Your central nervous system is then depressed, resulting in a calm, relaxed sensation. You're still conscious—in a vaguely euphoric state (there's a reason it's called laughing gas), and can hear and understand your dentist and their hygienist. Its effects don't linger, so you may need additional doses during your treatment session. At the end of the procedure, you will be given gas with an increased oxygen and nitrogen content to reverse the effects of the nitrous oxide. There may be a brief period of disorientation, a light headache, and even mild nausea—but these effects don't last, and you're generally okay to make your own way home.
Oral and Intravenous Sedation
When deeper sedation is needed, it will be delivered orally or intravenously. This is when more extensive preparations are needed, and it's important to clarify your obligations with your dentist. You may still retain partial consciousness (depending on the required level of sedation), but you might also be completely unconscious and unaware of your surroundings. At a minimum, you will need an escort—someone to drive you home or accompany you on public transport afterwards. You may even need some assistance at home for the remainder of the day, as the disorienting effects of oral and intravenous sedation may continue for a short period.
Eating and Drinking
You will receive strict instructions about eating and drinking prior to your procedure, and it's important that you treat these instructions as strict rules, and not lose guidelines. Failure to follow these instructions can make you feel extremely unwell, and can also disrupt the intended effects of the sedative. Be sure to clarify the best time for your last meal before your sedation, and you should aim to eat something suitably filling. Fluids are generally restricted in the hours before the procedure, with the only exception being when a small amount of water is needed to take any prescribed medications (and of course, your dentist will need to know about any medication you're currently taking).
It might be a bit disconcerting to be medicated for a dental procedure, but it exists for a reason, and that reason is your comfort. While some mild aftereffects are to be expected, they won't last.