Usage patterns
〈事〉の歯止めとなるto serve as a check/restraint on something
The new law served as a check on rising prices.
歯止めが外れるfor a restraint to come off, letting something run out of control
Once the restraint was lost, spending kept increasing.
〈物〉に歯止めを付けるto attach a brake/skid to something
We attached a skid to the wheel so it wouldn't move.