21.   The mouth guards are best spotted during free-throws in basketball and penalty-box minutes in hockey.

22.   The study, said LaBella, now at the Center for Athletic Medicine in Chicago, offers evidence that basketball leagues should also require the use of mouth guards.

23.   With at-home bleaching, a dentist produces a custom-fitted mouth guard that holds bleaching gel.

24.   The string of islands guard the mouth of the Red Sea and Gulf of Aden and their status has never been settled by international convention.