toothbrush transmission

I used my friend's toothbrush by mistake.. I have no reason to think that she would be HIV+ but I'm not 100% sure.  I've read a million articles on the internet which say that hiv transmission is possible via a toothbrush if both people's gums are bleeding etc.. My gums do bleed a lot at the moment.. but I don't know if her's do.  Presumably if she washed the toothbrush (which I think everyone does) after use then any blood on it wouldn't be there anymore and consequently no virus either?  I have no idea whether I used it before or after her so it may have spent a while in the open air or maybe only a few minutes.  
Is this a major risk?  Do I need to get tested after this kind of possible exposure?

[Teak]

No risk move on.

[siteheld]

Even if she is HIV positive you not at risk. I am sure you did not use it the same minute she did. HIV DOESN'T LIVE OUTSIDE THE BODY FOR LONG.

[anxiouslauz]

Ok well that's nice to know.  Why exactly is it that people with HIV are warned to not share toothbrushes and razors then?  Would you have to literally pass it over, one person to another, with blood to blood contact and without washing it?  

[anxiouslauz]

Could you comment for me teak?  I realise these kind of questions are irritating but I want to understand it more.  Because you read things on the net.. and they get contradicted.. its all very confusing!  But you seem to understand it all well.  Could you just confirm if what I wrote above is true?  And would the saliva´s natural defence inhibit the virus if it was in a tiny amount of blood in the mouth?

[HSci34]

No risk.