Objective To compare the clinical effects of fluor protector coating,atraumatic restoration treatment( ART)technique and traditional pit and fissure sealing for preventing dental caries of children's first permanent molars to look for the caries prevention technology suitable for school development. Methods A total of 600 children aged 7 to 8 years old with four of the first permanent molars( deep fissure but without caries) of all eruption( 2 400 teeth) were selected from2 schools. The subjects were divide...