My coverage at work is with Delta Dental. The premiums are pretty low but, of course, that is with an employer plan. They also don't cover a lot. It is $1500 max/year. There is an annual $50 deductible. They pay the cleanings and 50% on crowns. I just had to have a night guard made and they won't pay any of that $550.
If you have your billing records from your dentist you might want to take a look at what they "charge" compared to what the insurance company actually "pays". I see this all the time on my medical bills. The office visit might be $100 but the insurance company is only contracted to pay $60 and you are not responsible for the balance because they are contracted with the insurance company. If you have a long standing relationship with your dentist then I would approach him about giving you a discount just like he has been doing all along with the insurance company.
One other thing you can look into if you are getting ready to retire and have any sort of 401K, etc. is the possibility of a one time payment into a Health Savings Account. I don't know much about it other than you can pull money from your 401K into the HSA once, and only once, but I think it is tax free when you do that and then you would pay your dentist or whatever medical bill with the HSA. Hardly what you would call 'free' but it's something, at least.