The short answer to this question is that if the tooth is lost at the time in the child's life when it is generally expected to fall out, a new should grown into that space. If he was 4 years old when he let the tooth, his adult teeth should still come in. The only way to estimate how long would be to take him to the dentist and have the doctor do an examination.
About how long will it take to see a sign of his thooth? Been over six months if I can remember
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