Do not give up on Rehab, remember these people know what you are going through because many of them have gone through the same things. having support while your in Rehab is the best thing for you. You helping new people in Rehab is what will help you as well.
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!
Environment, health and population are interrelated.