According to structural modeling, preschoolers’ and their families’ oral health-related quality of life (OHRQoL) was severely impacted by the severity of early childhood caries (ECC). Weaker socioeconomic position, greater frequency of free sugar consumption, and weaker parental resilience were the key risk factors for the severity of ECC. The results show that psychosocial and behavioral factors might influence how severe ECC is, and that ECC can have a detrimental impact on preschoolers’ welfare and their capacity to carry out everyday tasks as well as on their families’ quality of life.