What
Tonsilloliths, or tonsil stones, are calcifications that form in the crypts of the palatal tonsils. They are also known to form in the throat and on the roof of the mouth.
How
Tonsils are filled with crevices where bacteria and other materials, including dead cells and mucus, can become trapped. When this occurs, the debris can become concentrated in white formations that occur in the pockets. Tonsilloliths are formed when this trapped debris combines and hardens, or calcifies.
Why
This tends to occur most often in people who suffer from chronic inflammation in their tonsils or repeated bouts of tonsillitis. They are often associated with post-nasal drip. These calculi are composed of calcium salts such as hydroxyapatite or calcium carbonate apatite, oxalates and other magnesium salts or containing ammonium radicals, macroscopically appear white or yellowish in color, and are usually of small size - though there have been occasional reports of large tonsil stones or calculi in peritonsillar locations. Many people have small tonsil stones that develop in their tonsils, and it is quite rare to have a large and solidified tonsil stone.