You usually start off with twenty baby teeth. If she is losing four each year you would divide the amount of baby teeth by four:
20/4=5
So she lost all her teeth by Five years of age.
PS. which is quite young!
you might want to see a specialist for something that you know is specifically is wrong with your body such as your having sight problems or hearing issues. You would see a primary care if you are just feeling sick or are hurting and you need a diagnosis to find out
