Dental Hygienist Digs for Unknown Ore

"What exactly ARE you digging for?"  The question banged over and over in my head as the young woman in front of me applied unnatural pressure to my bottom jaw with one hand, all the while dig-dig-digging at my molars with the world’s tiniest metal pickax in her other hand.  My silver fillings had been replaced long ago with some white composite material (which gives the impression of my teeth being way healthier than they probably are), so exactly what rock or ore […]