Children with restorative treatment needs will be included in the study's stage 2. In this second stage, primary molars with deep dentin lesions will be treated according to two techniques for selective excavation of carious dentin: subjective criteria or using an objective criteria (polymer burs). For both groups restorations will be performed using a high-viscosity glass-ionomer. In shallow and medium depth dentin lesions, carious dentin will be excavated using hand instruments only (ART approach) and restored using two materials: a high-viscosity glass-ionomer or a combination of a self-etch adhesive and a bulk fill composite.