I don't know but so many are abusing the visa on that category it's crazy. Suddenly everyone's teeth need attention from a Thai dentist haha. I can't see it being sustainable.
Because there are plenty of other options for a dentist appointment. You can even stay for 3 months as a tourist which is more than enough time to get any dental procedure done.
No disrespect to you, but I really hope they stop approving DTVs for all dentist appointment applications. It's just madness to expect a 5 year visa based on that.
London embassy. No stamps needed to be shown. I made sure all the documents I sent were enough so no questions were asked. I was worried they would call me in for an in-person interview or ask for proof of flights but it got approved pretty quickly without any of that.
Ask the owners of this group to help. I got mine without leaving Thailand (e-visa). I just need to leave and come back to get the first 180 days stamp which I am doing this weekend. But I have already been approved for DTV with documentation.