How do I fix this? My son is lost his two top teeth when he was five, he’s now 9 and they still aren’t in!!

Is this normal? I have been pretty calm and patient for these teeth to come in for years now but now I’m getting worried.When my oldest son was five he lost his two top teeth and when he was six he lost his two other teeth beside his two top teeth. Those grew in except for the first two incisors. His dentist has looked at his X-rays and said that those roots are not fully developed yet. He’s nine!! (Will be ten in a month) Those should be in by now. There’s literally nothing I can do expect wait patiently for these to come in. But how much longer should I wait for? I’m already really worried. via /r/Parenting http://bit.ly/2LHm7bS