@Shazawazza1969 My dental anxiety is strongest around needles but I have had several panic attacks at the dentist so I empathize with you deeply. If you have anxiety, they may happen to you sometimes and that's okay. Not every dentist will have experience with it and they don't always know how to react or what to do to help and that can leave you feeling foolish, but trust me: you aren't! Loads of us have trouble with this.
I believe you should be able to find a dentist who can work with you to help the root canal happen, even if you have to find a different one. If you are in pain, get a friend to help you call around and find someone who is experienced at working with anxious patients. DFC has
a really good page with red flags and signs you need a different dentist, as well as
one on how to find a new one.
It may help a lot just to let your dentist know that you may panic, what typically causes it, and tell them how they can best help you if it happens (for me, it's just sitting up the chair and being left alone for a few minutes). That way there is a plan in place, and you don't have to worry about trying to explain yourself in the moment.
You can also let them know what things cause your anxiety to spike in general to help them decide which accommodations to make. One option might be just having an assistant ensure adequate suction from your throat so you don't feel the need to swallow. You should also be able to control the suction tube yourself and position it where you need to to clear the saliva (I did this during mine on several occasions since they just left it hanging in the corner of my mouth, it just may be a bit tricky to maneuver around the dam). I actually had a root canal on #14 on Thursday without a dental dam. Granted, I live in the US and my experience here has been very different to others on this forum. I've never actually seen one used since I was a kid and I've had fillings at four different dentists since then.
When you are able, one thing which has helped me a lot was to learn about panic attacks and how to get through them. My therapist recommended this book, but admittedly I have not read it yet - "
Badass Ways to End Anxiety & Stop
Panic Attacks! by Geert Verschaeve". My preferred technique currently is a combination of acceptance, controlled breathing and meditation. I've also tried getting up from the chair and jogging in place (yep, I got weird looks but it was worth a try) and the full body clench and release - both of these are supposed to help relieve the fight-or-flight response you are experiencing. With luck, you can dramatically shorten the duration of panic attacks and lessen their impact on you. Then even if they happen, you may find yourself able to resume the procedure while you are still there.
Whatever you choose to do, please don't beat yourself up about being anxious. You are perfectly normal and not alone! Wishing you all the best.