Fifty primary molars were grinded on the occlusal surface to obtain flat dentin substrate and randomly divided into @ groups ( n = @ ) : OFL : Phosphoric Acid/Optibond FL/Premise Flow ; OAO : Optibond All-In-One/Premise Flowable ; II : Polyacrylic Acid/Fuji II ; IX : Polyacrylic Acid/Fuji IX ; V : Vertise Flow .