concious-sedation does work, I just had 3 root canals and an extraction last month and I didn't care at all during it or after.
I haven't been to the dentist in over 10 years because I was too afraid to, but now I'm not afraid at all and I still have more work to get done. Your son is older, he might be just fine with numbing and a little gas. I needed a bit more. I had a pill the night before, and 2 pills at the office, a little gas and that was it. I didn't have a drugged feeling, I just didn't care what they were doing. I could follow their commands with no problems.
My daughter, who is 10, had the whole extraction, head gear, braces thing, too. She also had an expander which I hated because I had to turn it each night and I felt like I was cracking her skull open.
adding: my kids when they were little had a ton of dental work done, they all had conscious sedation, too but they had some stuff to drink, no pills like me. They had extractions and caps and all that and are still fine about going to the dentist. They are 6 and 10 now.