This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Active fluoride concentration in the cavity varnish duraphat is: 
Select and explain. 
A. 22,900 ppm, B. 7,600 ppm, C. 22,600 ppm, D. 11,600 ppm
C: 22,600 ppm
Answer: C: 22,600 ppm 
Explanation: Duraphat, the first fluoride varnish developed in Germany.
	It is a viscous yellowish material, containing 22,600 ppm fluoride as sodium fluoride in a neutral colophonium base (NaF varnish containing 2.26% fluoride in organic lacquer). 
Duraphat has shown caries reduction between 30% and 40% in the permanent dentition and in between 7% and 44% in the primary dentition.

Essentials of preventive and community dentistry
Soben Peter
5th edition
page no. 255