There wasn't really anything you should have or could have done to change the course of this. Fortunately, this is still the primary or "baby" tooth, and it is likely that her permanent tooth will be fine. You should take her to see her dentist, however, so that it can be evaluated. The dentist may want to take x-rays to confirm that the permanent tooth is fine. I would make sure that you try and prevent her from injuring it again, as any further injury will likely disrupt the root.
Four-Year-Old Fell and Injured a Tooth
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