Objective. This study evaluated oral health-related quality-of-life (OHRQoL) in children and families before and after dental treatment under general anesthesia because of severe caries or molar-incisor hypomineralization (MIH). Materials and methods. A consecutive sample of the parents/caregivers of children (3–14 years) in need of treatment under general anesthesia participated in the study. The children were divided into two groups: 3–6 years and 7–14 years. The 49-item questionnaire that was administered before and after general anesthesia comprised the Child Oral Health Quality of Life-components of the Parental-Caregivers Perception Questionnaire (P-CPQ), the Family Impact Scale (FIS) and two global questions concerning oral health and general well-being. The P-CPQ domains were Oral symptoms, Functional limitations, Emotional well-being and Social well-being. The FIS items assessed impact on family life. Results. In both age groups, a significant decrease (p < 0.001) occurred in overall P-CPQ and the Oral symptoms, Functional limitations and Emotional limitations domains of the P-CPQ. Mean values for the Social well-being domain decreased significantly in the older (p < 0.05) but not the younger age group. Mean values for FIS decreased significantly in the younger (p < 0.001) and the older (p < 0.05) age groups. Conclusions. Dental treatment of severe caries or MIH, performed under general anesthesia, had an immediate effect on the oral health-related quality-of-life in the children in this study and a positive impact on the family situation.