How many scores are used in modified Dean's ﬂuorosis index?
(A) 4 (B) 6 (C) 8 (D) 5
(B) DEAN'S FLUOROSIS INDEX

It was introduced by Trendley H. Dean in 1934. It is also known as 'Dean's Classification System For Dental Fluorosis'.
The criteria for Dean's fluorosis index was based on a 7-point ordinal scale: normal, questionable, very mild, mild, moderate, moderately severe, and severe.

Dean's Fluorosis Index – Modified Criteria (1942)
6 points – Normal, questionable, very mild, mild, moderate, severe.
Essentials of preventive and community dentistry
5th edition
Soben Peter