I haven't done hypnosis, but I wanted to respond because I'm also a VERY nervous dental patient, and I just had a wisdom tooth removed.
First of all I wanted to let you know that it really really wasn't as bad as I'd feared. Second of all I wanted to let you know what I did do, which was to take Ativan about half an hour before the procedure to relax me. (My dr had prescribed it a couple of months ago for me to take before an MRI because I'm claustrophobic and I had some left over). As far as I know Ativan is ok to take while breastfeeding (my friend sometimes takes it for insomnia and is nursing her 1.5 yr old). Not sure if it sounds like the right answer for you, but I thought I'd throw it out there since it really helped me. You could talk to your dr about getting a prescription.
The other thing I wanted to mention. Not sure how many you need to have out, but I had one and I can't imagine having all 4 done at once. Just that I think during the first few days of recovery it really makes a difference to have one side of your mouth that you can chew with and one side of your face that you can sleep on. If I needed to have all 4 out I would do them 2 at a time (one side at a time). Just my 2 cents!
Kate, mom to 7 year old Djuna and 4 yr old Alden. Missing our good friend Hal the cat who died June 2, 2010