When a dentist is measuring how far gums have receded and looking for infection below the gum line they use a probe which they insert below the gum line and record how far it goes before hitting healthy tissue (or at least that is my understanding). They record the depth measurement of a tooth and then move onto the next using the same probe and without washing it in between.
It seems to me that this would be a great way to spread infection from one gum to the next. I asked my hygienist why this isn't considered unsafe. She started to explain to me why it wasn't dangerous and then caught herself and said "I don't know".
So am I right to be concerned? Might they be unwittingly spreading infection throughout the mouth by this seemingly unsanitary exam practice?