I've been using the Bangkok Hospital Dental Center in Bangkok since before it moved to the "new" building on Phetchaburi about twenty years ago. I use them, my wife uses them, and my nineteen-year-old son uses them. Along with cleanings and check-ups. I've had a root-canal, a crown and two implants. My wife has mostly just had a few new fillings and quite a few old fillings replaced. I do not think my son has had to have a filling on any of his permanent teeth, but he had to wear braces for a few years.
It is (I guess) a little pricy, but we have all been nothing but delighted with the services we have received there. My son's primary dentist was so good with kids I do not think he cried once, and he actually looked forward to going, and even wanted to be a dentist for a while.
Coincidentally, (no pun intended) my boy had his cleaning last week (THB2,132) and my wife and I had ours done today (~3,600 each) for thorough, 45-minute sessions.
I've had the same dentist for 15-20 years, and she is (as far as I can tell) the best I've ever had. I'm not changing. It is very convenient with parking and whatnot as well.
Incidentally, the "space-age" looking third floor is pretty new. The older floors are very nice, albeit much more traditional. The "new" floor has a digital "lab" with a 3D-router you can watch and a nice display of dental appliances which is pretty cool.