Which is better for a 4 year old, general anesthesia or nitrous oxide?

my son needs to have some dental work done, including caps on a couple of his front teeth. he is pretty anxious and i honestly dont think the work can be done with him awake. i dont care for the dentist that wants to put him under general, he is very arrogant, and i dont trust he will use porcelain caps i requested because he tried very diligently to convince me to go with metal. the only other dentist around, i do like and take my other children to does not use general at all. so bottom line of the question is it better to take the risks of general anesthesia or to take the risks with nitrous oxide (over several visits) and him not cooperating and possible getting hurt