My ortho says "It's one dose for each appointment, so if it was my body, I would err on the side of caution." I have two dentists - one up North & one down South - both require premedication for life because although the risk of infection is small, but the risk of occasional antibiotics is even smaller. My sister-in-law did get a systemic infection after extensive dental work that took a long time to cure (fortunately no implants at risk).
Sue