The active ingredient of anticalculus dentifrices is:

 # The active ingredient of anticalculus dentifrices is:
A. Fluoride
B. Potassium nitrate
C. Ammonia
D. Pyrophosphate

The correct answer is D. Pyrophosphate.

Pyrophosphate has received particular attention in view of its proposed rote in inhibition of crystal growth. Nevertheless, it is unlikely that pyrophosphate in toothpastes will persist for a reasonable length of time in the mouth, because of the presence of considerable amounts of pyrophosphatase enzymes in saliva and oral bacteria. Pyrophosphate, when introduced into a simulated oral environment, is hydrolyzed by various phosphatases with concomitant loss of its inhibitory activity for calcification in vitro. To overcome this problem, a copolymer of vinyl methyl ether maleic anhydride (Gantrez) and NaF has been introduced in order to inhibit the hydrolysis of pyrophosphate. Animal and clinical studies have shown that toothpaste containing a combination of pyrophosphate, NaF and Gantrez, was highly effective in retarding supragingival calculus formation. 

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