 The aim of this controlled clinical study was to evaluate the Neodymiun:yttrium aluminum garnet laser, with or without fluoride, in prevention of occlusal caries in the primary dentition. High caries risk children 7.61.4 years were selected for this study and received the following treatments: G1-1st molar was negative control, and the 2nd molar received a resin sealant; G2-1st molar was negative control, and the 2nd molar received laser irradiation 100 milliJoule, 5 Hertz - 0.5 Watts; G3-1st molar received only fluoride gel and the 2nd molar received fluoride gel laser irradiation; G4-1st molar received only fluoride varnish and the 2nd molar received fluoride varnish laser irradiation. Patients were followed up to 12 months to evaluate the formation of white-spot lesions andor caries cavities by three calibrated observers. 