 This study aims to evaluate the cost-efficacy and applicability of the treatment of lesions moderate caries using sealants as an alternative to the restorations on occlusal surfaces of deciduous teeth. 96 children aged 3-6 years will be selected. Children must have at least one occlusal surface classified as scores 3 or 4 of International Caries Detection and Assessment System ICDAS. Children will be randomly allocated according to the treatment: glass ionomer sealant and restoration with glass ionomer. After treatment, teeth will be assessed clinically after 6, 12, 18 and 24 months by trained and blinded examiners regarding the treatment received. The need of reintervention initially treated, either by failures that require repeating of the same procedure or for progression of caries lesions will be considered as primary outcomes. The secondary outcomes will be the chils acceptability to the treatment. 