With all due respect, and not to sound condescending, but can we please not start another thread that deals with sand. If you will utilize the search function on this forum you will find the answers to ALL of your questions.
Well to answer your question, you're better off not using sand. But if you clean/disinfect it often and feed him in another enclosure it lowers the risks of impaction and sickness. You shouldn't have young dragons on sand though, only fully grown adults.