Enamel loss ( SEM ) values for other European products and the reference control ( active agents ) were : Meridol ( ) : ( @,@ ppm F as AmF + SnF@ ) @ m ( @ ) ; Colgate ( ) Cavity Protection : ( @,@ ppm F as SMFP + NaF ) @ m ( @ ) ; Odol med @ ( ) ( @,@ ppm F as NaF ) @ m ( @ ) ; Elmex ( ) ( @,@ ppm F as AmF ) @ m ( @ ) ; Colgate ( ) Enamel Protect : ( @,@ ppm F as NaF + KNO@ ) @ m ( @ ) ; Lacalut ( ) aktiv : ( @,@ ppm F as AlF@ ) @ m ( @ ) ; Sensodyne ( ) ProNamel ( ) : ( @,@ ppm F as NaF + KNO@ ) @ m ( @ ) ; Crest Cavity Protection ( @,@ ppm F as NaF , reference control ) @ m ( @ ) ; and Mentadent ( ) : ( @,@ ppm F as NaF + Zn citrate ) @ m ( @ ) .