This randomized clinical trial is aimed at testing the efficacy of pit and fissure sealants, in a current environmental context different from that of the seventies and eighties. This study assesses the cost-effectiveness of sealants according to the individual caries risk. This study takes place in Nice, Marseille and Paris (France) and the patients are to be enrolled both in the dental hospitals and in the private practice. In the hospitals, the subjects are recruited directly by the headmasters of the pediatric dentistry or public health departments in the three dental schools. In private practice, the head of the department of pediatric dentistry and / or public health dentistry, of each dental school chooses 4 to 6 private practitioners who are used to place dental sealants in their daily practice. They recruit the subjects among their own patients. The type of study corresponds to randomized clinical trial (Split mouth design) in which the tooth is the statistical unit (one pair of molars considered for each included patient). This study has a direct benefit for individuals. The number of necessary subjects is 328; the sample size is 400. The follow-up duration is 2 years. The treatment is a pit and fissure sealant on one randomized tooth by pair of permanent molars (Split mouth design). Sealant material is set up in accordance with the usual practice of each practitioner. Occlusal exams are conducted every 6 months. The effectiveness of dental sealants and the retention of sealing materials are statistically analyzed according to both the individual caries risk and the clinical protocol