X-RAY CRYSTALLOGRAPHIC EXAMINATION OF CALCULI FROM SALIVARY GLANDS

¹ Royal Veterinary and Agricultural College, Copenhagen, Denmark

The recent development of the chemistry of so-called tricalcium phosphate is outlined. Apatite is the calcium phosphate generally deposited in the human or animal body. Whitlockite is rarely deposited except in calculi from salivary glands of which this is the first extensive crystallographic investigation.

Twenty-six calculi were examined by x-ray crystallography; 2 were pure whitlockite, 12 mixtures of whitlockite and apatite, 12 pure apatite, 2 calculi contained 2 to 4 per cent of crystalline calcite (calcium carbonate). It is concluded that saliva often, perhaps always, contains a factor impeding the precipitation of apatite.