My 5 year old is getting fillings

Kaye • OB/L&D TECH. Second girl due in November. Hoping for a vbac

And I am SO nervous about her appointment tomorrow. They said they may use local anesthesia if the nitrous doesn't work and of course I've heard all the bad things like it causing autism. Or other things. Can anyone reassure me please that I'm making the right decision for her ☹️