The patient should visit a great dental hospital in China's big

The patient should visit a great dental hospital in China's big cities.
If the patient does not have any major diseases, nor on any medications, the most common reason for these black spots might be dental hygiene and cell overgrouth issues. But to be safe, she probably needs to visit a good dental hospital in China's big cities. I only know Shanghai's No. 9 people's hospital. An biopsy might be needed to be sure.
Often, the problems in mouth belong to dental professionals, not the physicians.