est imation ▁of ▁the ▁disease ▁pre val ence . ▁ ▁A ▁full - mouth ▁exam ination ▁remains ▁the ▁best ▁method ▁of ▁accur ately ▁assess ing ▁the ▁pre val ence ▁and ▁sever ity ▁of ▁period ont al ▁disease ▁in ▁a ▁population . ▁ ▁The ▁use ▁of ▁the ▁CP IT N ▁system ▁for ▁ep ide mi ological ▁purposes ▁has ▁fla ws , ▁which ▁are ▁ground ed ▁in ▁a ▁number ▁of ▁historical ▁truth s . ▁ ▁At ▁the ▁time ▁the ▁system ▁was ▁designed , ▁the ▁init iation ▁of ▁period ont al ▁disease ▁was ▁thought ▁to ▁develop ▁from ▁a ▁continu um ▁from ▁an ▁infl amm ation - free ▁state ▁to ▁ging iv itis , ▁to ▁calculus ▁de position ▁and ▁pocket ▁formation ▁and ▁then ▁to ▁progress ive ▁disease . ▁ ▁Tre at ment ▁concepts ▁were ▁based ▁on ▁the ▁concept ▁of ▁pocket ▁depth s ▁being ▁the ▁most ▁critical ▁criter ion ▁for ▁surg ical ▁versus ▁non - s urg ical ▁treat ments . ▁ ▁This ▁index ▁was ▁also ▁designed ▁to ▁screen ▁large ▁populations ▁to ▁determine ▁treatment ▁needs ▁and ▁form ulate ▁prevent ive ▁strateg ies , ▁not ▁to ▁describe ▁the ▁pre val ence ▁and ▁sever ity ▁of ▁period ont al ▁dise ases . ▁ ▁Al band ar ▁( 1 9 9 9 ) ▁reported ▁on ▁data ▁from ▁the ▁Third ▁National ▁Health ▁and ▁N ut r ition ▁Ex am ination ▁Survey ▁( N H AN ES ▁III ). ▁ ▁This ▁was ▁derived ▁from ▁a ▁large ▁nation ally ▁representative , ▁strat ified , ▁mult ist age ▁probability ▁sample ▁in ▁the ▁USA ▁compr ising