My sister is 14 and looks older then she is, her teeth xrays show that she has the teeth of a 20 year old,she is very tall too, should we look into it?

Age: It is more common for girls to mature early. Your sisters doctor needs to check her and a concern would be if if he is off the growth chart. I think this is a normal growth spurt.

Look into it ?: As if she has an abnormal condition? Appears she is a tall 14 year old who is maturing into adulthood. If you are concerned, see what her pediatrician has to say.

Maturation: Some people mature faster than others, some slower. If your family has any concern about physical development, consult your sister's Pediatrician or General Physician. He/she can determine if visit to Endocrinologist is in order.