The present study aimed to evaluate the acceptability, represented by self-reported discomfort and cooperation, of children submitted to Conventional Restorative Treatment with Composite Resin under Rubber Dam Isolation and Local Anesthesia (CT) or Atraumatic Restorative Treatment (ART).This study is nested to a cluster-randomized non-inferiority clinical trial whose primary outcome was to compare the longevity of two restorative treatments in primary molars of children aged 3 to 6 years Session 1