FLUORIDE
Set to 2 different clues across 2 published puzzles, most often “Enamel strengthener” — The New York Times, Saturday, 5 January 2008.
8 letters
Every clue on record, most used first
- Enamel strengtheneronce
The New York Times — Saturday, 5 January 2008
- Protector of some caninesonce
The New York Times — Friday, 29 January 1999