Tenacious Stuff

So I saw the same patient that I had last week today. His perio abcess looks alot better and his tissue is responding well. I had sharpened all my instruments last Wed but I was still having the hardest time getting his calculus off. I used everything: ultrasonic, graceys, perio files, universal currets, etc... and I still missed like four areas. It will just not come off. I can't belive how concrete that stuff is.