I had two teeth extracted for orthodontic work without a working anaesthetic aged 11. The dentist put the needle in but didn't wait for it to take effect. I went into shock and collapsed, hyperventilated to the point that my arms and legs became paralysed. I was carried out of the surgery to the waiting room and my doctor was called, but by the time he arrived I was able to breathe a bit more normally.
When it came to have impressions done, the orthodontist used an adult plate and piled it high with thick pink gunge which made me gag furiously as it went down my throat and choked me. He held my head in a vice like grip for 5 minutes while it set. That would be repeated at regular intervals during the treatment. When the braces were put on, fortunately not cemented, I could not eat at all with them, and sat there with tears rolling down my face trying to eat the soft food my mother was providing. Eventually she lost patience, and told me to 'take the damn things out!' I never wore them for meals again.
When I went into hospital to have my wisdom teeth out, something went wrong during the procedure, my tongue fell back and they had to yank it forward with tongue forceps which cut a hole in it and it instantly started to swell. The surgeon deemed it too risky to continue, and I only had two teeth out instead of the four. My face came up like a football, and I could not eat for a week afterwards. The yanking open of my mouth damaged my TMJ joints, which have caused problems ever since.
Unsurprisingly I am terrified of the dentist. I panic at having things in my mouth, and can just about manage a checkup if I count down from 300 and tell myself to slow my breathing! X-rays are still a problem, the plate holders won't fit into my small mouth, and cut into my gums. I think if I needed anything more than a tiny filling, they would have to put me out!
Sorry for the long post, but you did ask!