How old is she?
Given that it's needs a stainless steel crown I assume it needs a pulpotomy (the nerve is chemically treated), I'd do it under GA, that way they cn also do x rays and do any other work needed, a lot less stress for DD and it's done in one go.
DD1 had some fillings done in April under GA, she was fine and I'm gad it did it that way, I'm a trined dental nurse!