 Methods: A total of 1,214 5-to-13 years-old children with at least one single or multiple-surface dentin caries lesion in primary or permanent molars will be selected in the public schools of Barueri-SP. The participants will be randomly divided into 2 groups: CT Filtek Bulk Fill - 3M and ART Ketac Molar Easy Mix - 3M and treated by ten untrained dentists in a dental office inside the schools. The restorations will be evaluated after 6, 12 and 24 months by an independent trained and calibrated examiner. The restoration and tooth survival, the cost-effectiveness analysis between the two groups and the operator preference of the treatment regarding the techniques will be also evaluated. Kaplan-Meier survival analysis and log-rank test will be applied to the survival of restorations. All the average event rates in the two groups will be modelled and compared with a Cox proportional hazard shared frailty model since there is an operator cluster-effect. The significance level for all analyses will be 5. 