The Relationship Between Neonatal and Maternal Factors and the Timing of Primary Tooth Eruption in Preterm Infants: An Observational Study in Iran.

BACKGROUND AND AIMS: Preterm birth is known to be associated with delayed primary tooth eruption, yet data on the factors influencing this delay in premature infants remain sparse. This study aims to investigate neonatal and maternal factors affecting the timing of the first primary tooth eruption. METHODS: In this retrospective-prospective cohort study, medical records of 145 preterm neonates (85 males) admitted to the neonatal intensive care unit at a tertiary center in Iran (January-June 2024) were reviewed. Comprehensive data were collected on maternal comorbidities, birth details, and neonatal status. Weekly follow-up interviews assessed tooth eruption and feeding status. Linear regression analysis examined variables against eruption timing for both chronological and corrected age, with a significance level set at p < 0.05. RESULTS: Median chronological eruption age was 8.0 [7.0, 10.0] months; mean corrected age was 6.5 ± 2.1 months. For chronological age, male sex (p = 0.015), higher gestational age (p = 0.001), and larger head circumference (p = 0.025) predicted earlier eruption, while higher magnesium delayed it (p = 0.045). For corrected age, lower gestational age at birth (p < 0.001), birthweight (p = 0.001), and head circumference (p = 0.002) were predictors of earlier eruption. Multivariate analysis showed that higher breastfeeding predicted earlier chronological eruption (p = 0.043), while lower gestational age at birth (p < 0.001), birthweight (p = 0.012), and head circumference at birth (p = 0.010) predicted earlier corrected eruption. CONCLUSION: Feeding status and anthropometric indices at birth emerged as independent predictors of tooth eruption. Exclusive breastfeeding associated with earlier chronological eruption, while earlier corrected-age eruption in more premature infants may reflect compensatory accelerated growth.