Had 2 deep fillings done.hours later feeling feverish &sore throat.next morning positive for strept & started duricef (cefadroxil). do i need to worry that strept entered bloodstream @dentist? (i have slight mvp)

Unclear question: Are you asking if the dentist gave you strep or if it is possible for strep to enter your bloodstream during dental work? Unless your dentist has poor sterile technique, s/he would be unlikely to give you strep. It sounds like you were already coming down with it and prompt treatment should lessen the risk of it going to your valve. To be safe, notify your doctor if you continue with fevers.

Vague: I would assume that getting the deep fillings and the symptoms of the strep are unrelated, but i would see a dr. To deal with what you have presently. Really hard to say.