I have going to the same dentist for six years. The office is not accessible though. But I have managed to get by with just my cane. However last year it was not enough. I just couldn't get to the exam room. I looked around and spotted an office chair and they used it like a wheelchair. A nice hack at the last minute.
This year I didn't want a repeat so when I called to make an appointment I reminded them of last year's episode. I asked if they had considered getting a wheelchair for the office. They put me on hold for a couple of minutes. When they came back I was informed that they just ordered one and we set up my appointment.
All I had to do was ask.