Effects of intergenerational parent-child separation on early eruption of permanent molar and telomere length: a cross-sectional study among Chinese children aged 3–6 years

Parent-child separation is a risk factor for children’s physical and mental problems, limited literature has explored the impact on children’s development across generations. Here, we examine the effects of intergenerational parent-child separation on accelerating biological aging in preschool children, as indicated by the accelerated eruption of the first permanent molar (M1) and oral epithelial cell telomere length (TL). This study draws on data from a child growth cohort established in rural areas of Anhui Province, China, which included 2,367 children aged 3–6 years. Researchers collected data on parent-child separation experiences and demographic characteristics of both parents and offspring, followed by comprehensive physical and oral examination. Parent-child separation during the parents’ childhood and their children’s separation experiences were recognized as distinct generational exposures, while intergenerational continuity of parent-child separation was defined as both generations experiencing separation. During dental examinations, M1 eruption was classified as accelerated if occurring before 6.1 years in girls or 6.3 years in boys. A follow-up oral examination was conducted six months later, with oral epithelial samples collected for TL measurement. Children with missing data, deciduous dentition or undetermined M1 eruption status were excluded, yielding a final sample of 895 children (mean [SD] age: 6.01 [0.14] years). Among these, 179 (20%) experienced intergenerational continuity of parent-child separation. The included children with a mean (SD) age of 6.01 (0.14) years. The overall prevalence of accelerated M1 eruption was 28.7% (257/895). Children exposed to intergenerational continuity of parent-child separation showed a 2.03-times increased risk of accelerated M1 eruption (95% CI: 1.24–3.33, p = 0.005), and 23% shorter telomeres (95% CI: -0.32 to -0.14, p < 0.001) compared to unexposed children. Sensitivity analyses revealed that both paternal and maternal transmission contributed to accelerated biological aging in the oral cavity, though paternal transmission showed stronger effects. Our findings demonstrate that intergenerational parent-child separation adversely impacts biological aging in the oral cavity of preschool children. These results underscore the critical need to break the intergenerational cycle of parent-child separation in children’s oral health and overall health.