IADR Abstract Archives
Exploring the aetiology of Hypomineralised Second Primary Molars: A longitudinal twin study
Objectives: To use a longitudinal twin study to investigate the relative contribution of genes and environment to the aetiology of Hypomineralised Second Primary Molars (HSPM) and to identify potential environmental risk factors for HSPM.
Methods: Twin pregnancies were recruited antenatally from three Melbourne hospitals between 2007 and 2009. Detailed demographic, health and phenotypic data were collected at recruitment, 24 and 36-weeks gestation and from the twin offspring at birth and 18-months of age. Maternal 25-Hydroxyvitamin D was quantified at 28-weeks gestation and offspring 25-Hydroxyvitamin D at birth. Dental examinations were conducted on the twins at six years of age to determine the presence, severity and extent of HSPM, using standardised criteria. Twin-twin concordance was calculated for monozygotic (MZ) and dizygotic (DZ) pairs. To investigate associations between environmental risk factors and HSPM, multiple logistic regression models were fitted using generalised estimating equations to adjust for twin correlation.
Results: 250 twin pregnancies were recruited and 344 twins underwent the 6-year old dental assessment. HSPM occurred in 68 (19.8%). Overall concordance for HSPM was 0.46 (95% CI 031-0.61) and there was weak evidence of higher concordance in MZ twins (0.59, 95% CI 0.31-0.86) than DZ twins (0.42, 95% CI 0.24–0.59) . After adjusting for potential confounders, maternal smoking in the 3rd trimester, dizygosity, infantile eczema, and higher socio-economic status were significantly associated with HSPM. Risk factors such as low birth-weight and acute childhood illness previously implicated in retrospective studies were not associated with HSPM.
Conclusions: These findings suggest that shared genetic and environmental factors, and unshared early life factors are important in the aetiology of HSPM. Maternal smoking during the third trimester and infantile eczema showed the strongest evidence of association with HSPM. Interventions to reduce smoking in pregnancy and further research into causes of eczema and potential shared biological pathways may have benefits for later dental health.
Methods: Twin pregnancies were recruited antenatally from three Melbourne hospitals between 2007 and 2009. Detailed demographic, health and phenotypic data were collected at recruitment, 24 and 36-weeks gestation and from the twin offspring at birth and 18-months of age. Maternal 25-Hydroxyvitamin D was quantified at 28-weeks gestation and offspring 25-Hydroxyvitamin D at birth. Dental examinations were conducted on the twins at six years of age to determine the presence, severity and extent of HSPM, using standardised criteria. Twin-twin concordance was calculated for monozygotic (MZ) and dizygotic (DZ) pairs. To investigate associations between environmental risk factors and HSPM, multiple logistic regression models were fitted using generalised estimating equations to adjust for twin correlation.
Results: 250 twin pregnancies were recruited and 344 twins underwent the 6-year old dental assessment. HSPM occurred in 68 (19.8%). Overall concordance for HSPM was 0.46 (95% CI 031-0.61) and there was weak evidence of higher concordance in MZ twins (0.59, 95% CI 0.31-0.86) than DZ twins (0.42, 95% CI 0.24–0.59) . After adjusting for potential confounders, maternal smoking in the 3rd trimester, dizygosity, infantile eczema, and higher socio-economic status were significantly associated with HSPM. Risk factors such as low birth-weight and acute childhood illness previously implicated in retrospective studies were not associated with HSPM.
Conclusions: These findings suggest that shared genetic and environmental factors, and unshared early life factors are important in the aetiology of HSPM. Maternal smoking during the third trimester and infantile eczema showed the strongest evidence of association with HSPM. Interventions to reduce smoking in pregnancy and further research into causes of eczema and potential shared biological pathways may have benefits for later dental health.