IntroductionOral and dental health is one of the most important factors that affect the quality of life of preschool children. This study determined the effect of oral and dental health of preschoolers on their quality of life and that of their parents.MethodsThis descriptive-cross sectional study asked 304 mothers of children aged 2–5 years from Babol, Iran, to complete an Early Childhood Oral Health Impact Scale (ECOHIS) questionnaire. Higher raw scores for ECOHIS indicate more oral problems and lower quality of life as related to oral health. The demographic information and dmft indices of the children were documented. The data were analyzed using the independent sample t-test, one way ANOVA, and the Scheffe post hoc test.ResultsThe mean ECOHIS score was 6.65 ± 3.57, and the mean score of “decay, missing and filling teeth” (dmft) was 4.39 ± 3.68. A high correlation (r = 0.725) was observed between the dmft score and the ECOHIS score (p < 0.001).ConclusionThe oral and dental health of the children strongly influenced their quality of life and that of their parents. There was an inverse relationship between dmft and oral health-related quality of life.