When your toddler falls, damage to their teeth can certainly occur. If a tooth is knocked loose or out, you should call your dentist. If your dentist is not available, the emergency room is a viable option. It has been my experience that many emergency room physicians are not educated in dental treatment, so I would try to get a dentist to evaluate your child.
When a baby tooth is knocked out, we usually will not replant it into its socket, as our primary concern is the health of the permanent tooth, which is already forming right by the root of the baby tooth.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.