Hi Clover.
Just came across your thread, sorry for my late contribution. My brother and sister (43 & 37 years old respectively) still have some baby teeth (they have many absent adult teeth). When my nieces were born they had some tests done and it turns out they have a condition called Ectodermal dysplasia which affects their teeth, hair and nails. Our guess is that my brother & sister have same, though as far as I know they haven't been tested.
I'd recommend getting some testing done in case your DD has a syndrome or condition that explains the lack of adult teeth. Reason being, back in my brother & sister's childhood there really wasn't much my parents could do for them (other than fork out for braces), and now my sister is looking into implants, bridges etc & its all very complex and exceptionally expensive. My niece on the other hand was covered by Medicare for her paediatric dental/orthodontic needs because of the syndrome. (The only affect on hair & nails is that they've a fair bit of frizz and their nails can have ridges - no big deal! But teeth are a big deal, and are always so expensive to do anything about.) She has had braces and they were covered.
I hope you get some answers and some assistance for your DD.