Pills or I.V.
For minor sedation, you can take pills, often 1 the night before, and then 1 or 2 before your dental visit.
For longer procedures, or if you need to be sedated more deeply, you'll get an I.V. With a drug administered directly into your vein. Both work great for the right person & procedure. It really depends on what you need, what's being done, & what makes the most sense to you. Ask your dentist.