Toothless (1997) on Netflix

Good but reserved dentist Katherine, dies instantly from her injuries in an accident, finds herself in Limbo, needing to account for her life, and correct her one flaw before being admitted to heaven: not being able to let herself love others. Selected as The Tooth Fairy, she has to collect kids baby teeth every night, and soon learns the kids can see her, but not the adults. Inadvertently offering advice to troubled Bobby, she finds her fame spreading around his school. Soon, all the kids start losing their teeth to induce her visits, and get help with advice, lessons, bullying, etc. But the parents react negatively to all the talk of The Tooth Fairy, while Katherine gets into trouble for interfering with human lives.