The federal agency said it is sending letters to 1,812 veterans who received treatment at the St. Louis VA Medical Center during a 13-month period ending in March, the St. Louis Post-Dispatch reported Wednesday.
The letter said dental equipment at the facility wasn't being properly cleaned and as a result there was an "extremely low" risk of infection.
The letter offers free blood tests to screen for HIV and the hepatitis B and C viruses.
U.S. Rep. Russ Carnahan, D-Mo., sent a letter to the head of the VA requesting a formal investigation of the matter. Carnahan called the potential exposure an "indefensible breach of standard operating procedure."