I recently had a patient with recurrent decay at the margin of two lower molar crowns. We used Silver Diamine fluoride (Advantage Arrest) at the margins to arrest the decay. As predicted the tooth structure turned hard, but also black and the area stayed cavitated. I was then faced with the tough decision when replacing the crown of dropping the margin multiple millimeters to cover the area we had treated or leaving the margin for the new crown on the tooth structure we had treated with the fluoride. As a brand new process I am curious how other people are using Silver Diamine Fluoride?