Purpose. To check the efficiency over time of four different classes of materials (ormocers, sealing composites, compomers, glassionomers) for sealing pits and pits and their clinical evaluation on permanent first molars. Material and method. A group of children was selected with first permanent molars that met the sealing requirements and the first molars were sealed, following the application technique and the time duration (18 months) of the retention of the materials on the surfaces hard teeth and if carious lesions have appeared on the sealed surfaces. Results. Each group of material itself presents different chemical properties, which gives them some advantages. The most resistant material being the one from the ormocer class, having the highest retention in the two years (89%) and the least resistant being the one from the glass inomer class (71%). The most difficult to handle is the ormocer. And as the appearance of carious processes, all four present a small percentage (below 8%). Discussions. All four classes show satisfactory durability over time and the percentage of new carious processes is low. Conclusions. For the prevention of carious processes on first permanent molars, the materials studied in this study are efficient.