Undeterred, I give my toothbrush a brisk wash and try again, this time more tentatively. The small, brisk-but-gentle movements that Hirschfeld carefully described to me are surprisingly difficult to emulate. As a right-hander, it feels something like attempting to write in neat cursive script with my left. By the time I"ve painstakingly negotiated my entire gumline – upper, lower, inside and out – with an attempt at the modified Bass, I check my little green hourglass. My two minutes are up, who knows how long ago, and I haven"t even started flossing yet.