Maternal age and oral health-related quality of life in preschool children: the mediating role of dental caries in a cross-sectional study.

INTRODUCTION: Early Childhood Caries (ECC) is a highly prevalent chronic condition that disproportionately affects children in socioeconomically vulnerable settings and negatively impacts oral health-related quality of life (OHRQoL). While maternal age has been identified as a relevant factor, the mechanisms linking maternal age to children's oral health outcomes remain insufficiently understood. This study aimed to examine the relationship between maternal age, dental caries experience, and OHRQoL, and assess the mediating role of dental caries in this relationship. METHODS: A cross-sectional study was conducted in 183 mother-child dyads involving 4- and 5-year-old children attending a primary healthcare center in Coquimbo, Chile. Dental caries experience was assessed using the decayed, missing, and filled teeth (dmft) index, and children's OHRQoL was measured using the Early Childhood Oral Health Impact Scale (ECOHIS). Statistical analyses included non-parametric tests for group comparisons, regression analyses, and mediation analysis using a regression-based approach with natural log-transformed variables. RESULTS: The mean maternal age at childbirth was 22.6 ± 6.7 years (range: 12-39 years), with mothers distributed across the full maternal age continuum. Caries prevalence was 55.7%, with a mean dmft score of 2.25 ± 2.63, and the mean total ECOHIS score was 18.4. Maternal age was inversely associated with both dental caries experience and children's OHRQoL impairment (both p < 0.001). Dental caries experience was strongly associated with poorer children's OHRQoL, explaining 85.5% of the variability in ECOHIS scores (p < 0.001). Mediation analysis indicated that dental caries represented an important pathway linking maternal age to children's OHRQoL, accounting for 57.8% of the total association. The negative indirect effect (p < 0.001) was consistent with a protective pathway whereby increasing maternal age was associated with better children's OHRQoL through reduced dental caries experience. CONCLUSION: The mediation analysis suggested that dental caries constituted an important component of the association between maternal age and children's OHRQoL. The analysis of maternal age as a continuum provided a more comprehensive understanding of inequalities in early childhood oral health and reinforced its interpretation as a marker of broader social and contextual conditions influencing children's oral health. These findings support life-course and equity-oriented strategies for improving children's oral health and reducing oral health inequalities.