The Dunkirk Hospital said Tuesday it is investigating how its personnel handled the treatment of 85-year-old Roland Marissael.

La Voix du Nord newspaper reported that staff at the Dunkirk Hospital and Cambrai Hospital Center thought he was suffering from lung problems or dementia and refused to check his throat. Marissael’s sons Jean-Jacques and Jean-Luc are quoted as saying they repeatedly told medics that he had accidentally swallowed his dentures.

The report says that an X-ray eventually revealed the false teeth were trapped in his vocal cords, and surgeons immediately removed them.

The Dunkirk Hospital says Marissael remains hospitalized.