It is helpful to recall Dr. Costerton’s diagramatic pics of mature biofilms to develop a conceptual understanding of what you are observing. In looking at “the good root” in our fracture case (the root that wasn’t fractured), one wouldn’t expect a mature biofilm…but that is exactly what we see….everywhere. Shedding of planktonic cells from the biofilm. See if the diagram helps in understanding what you see here.