I know a MD or a dentist has his/her name written like นพ/ทพ/พญ/ทพญ and their surname written after the title on signs etc, but how about in everyday life? Is the Dr addressed by people by their title or by "khun"? How is it on paper, e g on invitations?

martin , snap out of it! It only matters if you work for the dentist which you dont. Who cares if your paying for a service your the boss, its a matter of how they should be addressing you. Not the other way around. Unless of course your seeking respect by acknowledging a superior? what would you call a pilot who just flew you 24 hours at 37,000ft? in first class he would address you as sir, most people don't know that

Just sarcastic to much wine and bed time now last post

what would you call a pilot who just flew you 24 hours at 37,000ft? in first class he would address you as sir, most people don't know that

Well, as American police officers addresses crackheads, drunk drivers and so forth, with sir, I wouldn't acknowledge it as a respectfull title

I usually use Doctor, or if associated with a university, Ajarn.... I think either is pretty much respectful enough.

In English (which most Thai doctors are fluent in) I use Doctor, except the medical professors who are addressed as Ajarn by nurses and by me.

Depends on how well you know him/her, Dr. that I have used for several visit and know I call by their first name. Those I don't know I call Dr.

Informally I suppose คุณหมอ Khun maaw® while speaking and นายแพทย์ Nai phaaet(f) in writing. คุณหมอ Khun maaw® and นางแพทย์ Narng phaaet(f) for a female doctor.

It is not necessarily set in stone and depends on your relation to the person in question.

The medical doctors and university professors in my circle of acquaintances are usually addressed as อาจารย์.

Informally I suppose คุณหมอ Khun maaw® while speaking and นายแพทย์ Nai phaaet(f) in writing. คุณหมอ Khun maaw® and นางแพทย์ Narng phaaet(f) for a female doctor.

นายแพทย์ - male doctor, ทันตแพทย์ - male dentist.

แพทย์หญิง - female doctor, ทันตแพทย์หญิง - female dentist.

The above titles are used in formal speech or writing.

As for daily life, the only title which is safe to address a doctor or a dentist, male or female, is คุณหมอ.

I don't think anyone who is not a teacher or professor or have never really taught other in real would be happy to be called อาจารย์, only a fake one would be though.

If you want to be pedantically correct when you are addressing somebody in written Thai, read This Article .

It says that you leave a space between an academic's title and their name if they have a doctorate or a military rank. No space if they don't, or if you are abbreviating their academic title.