Just wanted to confirm what suzy said.
Dentists are required by law to sterilize every tool used.
Once the tools are sterilized they are placed into bags, and sealed. When the dentist comes in to work on you, he will open that bag... Usually in front of you, so there is no question about it... And if he doesn't, you can always request it.
And as for the needles. Once a needle is used, it is thrown away immediately.
While you are in the dentists office, look around on the walls... There are usually little bins that say something like "sharps" or "wallmate" on them... They are for disposing the needles.
don't worry about it. There are so many laws out there, and they are there to protect you!
Good luck with your surgery.
~qriosity~