Competitive swimmers may be at risk for developing yellowish-brown or dark-brown stains on their teeth, reports the Academy of General Dentistry (AGD), an organization of general dentists dedicated to continuing dental education.

Athlete swimmers, who often swim laps more than six hours a week, expose their teeth to large amounts of chemically treated water. Pool water contains chemical additives like antimicrobials, which give the water a higher pH than saliva, causing salivary proteins to break down quickly and form organic deposits on swimmer's teeth.

The result is swimmer's calculus, hard, brown tartar deposits that appear predominantly on the front teeth. "It's a common cosmetic condition among swimmers," says AGD spokesperson J. Frank Collins, DDS, MAGD. Swimmers who notice the stains should talk to their dentist and perhaps increase their dental visits to three or four times a year, advises Dr. Collins.

During the summer, swimming pool accidents are the number-one cause of dental emergencies at the office of E. "Mac" Edington, DDS, MAGD, past president of the AGD. "Swimming underwater and quickly coming to the surface causes some children to hit the hard ledge, loosening the front tooth," says Dr. Edington.

Also, running on slippery, slick cement and ceramic pool surfaces sends many children headfirst into the ground, often causing chipped or displaced teeth. "Diving into shallow waters and hitting the bottom pushes the tooth up and can fracture the whole bone," says Dr. Edington.