Purpose: The purpose of this study was to evaluate the oral health-related quality of life (OHRQoL) of preschoolers before (T1), 15 days (T2), and three months (T3) after carious lesion treatments using 30 percent silver diamine fluoride (SDF, <small>N</small> equals 59) and atraumatic restorative treatment (ART, n equals 59). Methods: Data about sociodemographic aspects and OHRQoL through the Early Childhood Oral Health Impact Scale questionnaire (B-ECOHIS) were collected between 2016 and 2019. Total B-ECOHIS, impact on children (CIS), and family (FIS) values were used. The Mann-Whitney test compared these values, and the effect size (ES) of treatments was also calculated. Results: Toothache and upset/ guilty parents were the most reported impacts on T1. Total B-ECOHIS did not statistically vary between girls and boys or children older or younger than four years old, and socioeconomic status was not a factor either. Total B-ECOHIS, their impacts, and subscales were higher in children with high decayed, missing, and filled primary teeth (dmft) scores (P<0.05). SDF and ART did not vary among B-ECOHIS, CIS, and FIS at any time (P>0.05). Total B-ECOHIS decreased for both treatments (P<0.05). The ES was moderate for children in T2 and T3, considering all treatments, while for families the ES was moderate at T2 and small/moderate at T3 after treatment with SDF and ART, respectively. Conclusion: Treatments with 30 percent silver diamine fluoride or atraumatic restorative treatment improved the oral health-related quality of life of preschoolers, with no variation among those treated.