My 9 year old son fractured his two front upper teeth and the dentisit here first bonded them now she has crowned them permanently but his gums are swollen and painful is tooth crowning OK at age of 9?

See the dentist and do a follow-up, that's the only thing I would suggest,

Normally adult teeth aren't permanently crowned until age 18 since the teeth have not grown all the way in yet.
Tooth could be painful because it has abscessed since it was fractured. The dentist should check its vitality and take an x-ray to check the root tip.
Gums are probably swollen due to the work that has been done. Have your son brush gently and rinse with warm salt water. Tell him to brush even if it makes them bleed but to do it gently.