[corkoman]

Yes - 25 mg is quite a load to scrape off of fossilized or glacier-preserved teeth.

Maybe 25 mcg? Thats gotta be it.

[TXnMA]

On the question of mg vs µg, perhaps we should keep in mind that the sources of these tartar samples never went in for periodic teeth cleanings -- or, even, had toothbrushes, etc.

A dentist friend of mine who goes to underdeveloped countries on summer missions trips, says that he is astounded at the big chunks of tartar he pries off of patients' teeth -- even young adults'...

[gleeaikin]

A baby aspirin that many take to lower the rate of heart disease contains 81 mg of aspirin plus binders and fillers. A gram contains 1000 mgs. A level teaspoon of sugar contains 5 grams. It is not hard to find 25 mg. of tartar on poorly cleaned teeth.