One of the Triumphs for this year's Festival of the Lost, apparently requires my Guardian to brush my teeth. This doesn't really seem to be very descriptive, but is a required triumph to obtain the Eris Morn mask.
Now I've tried some things -- I've tried talking to tower vendors for toothbrushes they might sell, but I've come up short. I've tried brushing my own teeth in real life, but Bungie hasn't notified me of completion there, so that's a no.
In any case, how do I brush my teeth to get A Brilliant Smile?