Purpose: To assess children's oral health-related quality of life (OHRQoL) three years after implementation of three treatment protocols for managing cavitated carious dentine lesions in primary molars by parent proxy report with the Brazilian Early Childhood Oral Health Impact Scale (B-ECOHIS) and to assess the level of agreement between the children's self-reporting and the parents' reporting of the children's OHRQoL. Materials and Methods: Schoolchildren aged 6 to 7 were included in a clinical trial that compared three treatment protocols for managing cavitated carious dentine lesions: CRT (Conventional Treatment); ART (Atraumatic Restorative Treatment) and UCT (Ultraconservative Treatment). Before treatment (baseline), the OHRQoL of 273 children was assessed by B-ECOHIS using the parents'/caregivers' proxy report. Three years later, 147 parents/caregivers filled in the questionnaire while the children, ages 9 to 10, were interviewed. The t-test and one-way ANOVA were used for statistical analysis. Results: No difference was observed between treatment protocols in regard to the children's OHRQoL (p = 0.41). A significant reduction in the parent distress domain was observed when baseline and parents'/caretakers' responses after three years (p = 0.01) were compared. The level of agreement between the parents'/caregivers' and children's scores was low. Children scored lower on the impact of oral health on their quality of life than their parents/caregivers did (p 0.0001). Conclusion: The use of UCT, a largely non-restorative protocol, leads to a perception of OHRQoL by parents/caregivers that is similar to the ART and CRT protocols after three years. Parent distress decreased over time. Children and parents/caregivers disagreed about children's OHRQoL. Keywords: atraumatic restorative treatment, conventional restorative treatment, ECOHIS, quality of life, ultra-conservative treatment