I don't know if this is a bug or something, but I had 3 on the 3rd on the X1 and when I played mayhem on the 360 the bonus pool reset to zero teeth.
Also off topic maybe someone here knows how I received a tooth for every hive destroyed leading up to the kraken mini boss fight. It happened the first 3 times giving me 9 teeth total as I got one for the kraken hive as well.