All I can tell you from experience is that while on holiday in Langkawi, Malaysia I got really bad toothache and had to see a dentist (I was actually advised to wait til I could back get to Bangkok but it hurt too much!). To my surprise the dentist (a Dr Chew, lol!) was brilliant - clean, modern, trained in UK - and did a root canal and lovely white filling for £11!!! I even got a load of x-rays to take away for my UK dentist, who said it looked like a job well done.
While I was in the waiting room I got chatting to two American men who went on holiday to Langkawi every year and had both routine and cosmetic treatment done there each time. They had never had a problem and had saved thousands.