J.S.
R.,
Although my daughter has not had a frenectomy, she did have oral surgery when she was 4, almost 5. It was so scary for ME when she came out of her anestesia. The Dr. told me that she would be kicking and screaming and I would have to hold her down and restrain her, but that she would not remember any of it.
It was like a possessed person that you'd see in the movies and I did NOT want for her to remember ME holding her down and restraining her. But, (thank the LORD) she did not remember it.
SO, although I can not tell you about the surgery part of your question, I can tell you that as far as her remembering the pain of the procedure, it was not a problem with my daughter even at almost 5 years old.
I hope this helps you :-)