Hi Stewart,
happy to answer.
1) I was a dental nurse particularly responsible for people who came to see us the first time and reported having dental anxiety. My job was to pick them up from the waiting room and have a chat with them to understand the dental issues but also the fears and origins of their phobia. It was also my job to make them feel comfortable, show them the treatment room and make sure they are okay before the dentist comes in. I also briefed the dentist and made suggestions on how to make things easier for them. During times when no new patients were coming in I did what a dental nurse does - assisting with filling, doing x-rays, educating, sanitizing the treatment room etc. I also assisted during treatments with laughing gas.
2) I don't have any statistics on that.
3) In my practice most of them. No idea about percentages
4) During a treatment? Barely any. If - despite all measures to make the treatment pain free - a dentist or a nurse spotted anything indicating that the patient was in discomfort, we would stop and check what was going on and wouldn't go on until that was resolved. Pain creates anxiety so providing pain-free treatment is a basis for the work with nervous patients of any kind. But I saw many people who came in for emergency treatment who came in because they were in pain, very often people with severe anxiety who got "forced" to go due to an emergency.
5) There is no general answer to this. Depends on what the person is scared of, what were the past experiences, what they have tried and what needs to be done for them to become confident again. The intake apts sometimes took up to an hour, depending on when the patient was ready to enter the treatment room and let me call in the dentist. The chat beforehand was always in a cozy living room setting. And it happened ocasionally that the patient still wasn't ready or got very stressed at the sight of the treatment room and we had to pick another appointment to try again.
6) Once everything is sorted and the person has a good hygiene and way of eating, without underlying conditions, a cleaning and regular checkups are enough to keep that state. My experience is exactly that - after everything is sorted, people only come in for cleanings and checkups and do not need more treatment. People who were lucky to be thaught oral hygiene and to have good nutrition from childhood already may never need any work at all.
Hope this helps
All the best wishes