Space Maintainer for a little kid

[Janet]

Is there a need for a space maintainer for the upper primary first molar. My 4 year old will not let the dentist put it in due to anxiety after he got it extracted. I have read that it is always necessary so I just want to know the extent we should go to get it put in. I really want to proactively avoid braces for my little one. If we are not successful will that space close up. He has very gappy teeth