The aim of this study was to test the hypothesis that the conventional restorative treatment (CRT) and the atraumatic restorative treatment (ART) protocols, in comparison with the ultra-conservative treatment (UCT) protocol, would increase the quality of life of children over a period of 1 year. Cavitated primary molars of 302 children 6–7 years of age were treated according to the CRT, ART and UCT protocols at the school compound. Children's parents completed the Brazilian version of the Early Childhood Oral Health Impact Scale (B-ECOHIS) at baseline and one year later. Paired t-test, Chi-square test and anova were applied in analysing the data. Questionnaires from 277 and 160 children were collected at baseline and after 1 year, respectively. A statistically significant difference in B-ECOHIS scores over the 1-year period was found for domains ‘child symptoms’ (P = 0.03) and ‘child psychology’ (P = 0.02). Treatment protocols did not statistically significantly influence the changes in B-ECOHIS scores over the 1-year period (P = 0.78). It can be concluded that the UCT protocol was as good as the two restorative protocols. All treatment protocols were effective in reducing children's experience of pain, their sleeping problems and their irritability and/or frustration levels over the 1-year period.