"You know I can take her if I wish." Which would seem to indicate, at least, a belief on her part that Coyote would be incapable of stopping her once she decided on a course of action.
So I agree that she doesn't believe that he can harm her. However, Tavar is correct in noting that this belief may be based on ignorance. She only has her experience to draw from when concluding that there is nothing in existence that can damage her or which (aside from herself) cannot be damaged by her. If a new material were to surface that was sharper or more durable than anything she had tested previously, she would not be able to know for certain in advance that it would not be able to damage her or that she would be able to damage it. So I don't think we can draw a solid conclusion either way about whether the tooth is capable of harming her.