My SIL is a hygienist and is freaky about teeth She recently took her daughter (nearly 2) for her first checkup. It was just about familiarisation, the chair, the room etc. He didn't even look in her mouth!!
I think the biggest thing will be you staying calm. Milo will pick up if you are stresesed and he will misbehave! So take a deep breath, and as long as you haven't been feeding him lollies by the truckload, and juice out of a bottle, I'm sure he will be OK.