A. it is not advisable to have a child of 6 to have a crown. As the abcess has returned after a short period of time, then I would have the tooth taken out. The fillin that has fallen out in the other toth needs to replaced as soon as possible to stop an abcess from forming on that tooth. It is an unfortunate situation that you are in and I do feel for you. I just need you to be aware that ideally, you need to get to the root cause of why your child is having to have lots of fillings and has already had an abcess. You need to assess your child’s diet and limit the times of the day when your child has sugary foods/drinks. Sugar, as I’m sure you’re aware is the main contributing factor in tooth decay. If you restrict sweet treats to mealtimes, then this will stabilise the sugar in the saliva and prevent decay. Hope this has helped.