2. Lingual orthodontics can be done as long as the teeth are not too small.
3. Tongue therapy needs an adaptation period, which varies from person to person. There must be discomfort at first. An average adaptation period of about one month will affect pronunciation, which is called Lickitung. There is also the inconvenience of eating and the feeling of foreign body will make your tongue hurt.
It seems that only Beijing, Shanghai, Guangzhou and other cities have developed this technology. I don't know if you have a price there, but it depends on what slot you use. At present, the American groove processed by the United States and Germany is larger, while the German groove is relatively smaller and easier to adapt. About 30,000-40,000 in the United States and 40,000-50,000 in Germany. This is the current price ~