Heritability of Caries Scores, Trajectories and Disease Subtypes

Previous studies report that dental caries is partially heritable but there is uncertainty in the magnitude of genetic effects and little understanding of how genetic factors might influence caries progression or caries subtypes. This study aimed to estimate the relative importance of genetic and environmental factors in the aetiology of different caries outcomes using a twin-based design.
Analysis included up to 41,678 twins in the Swedish Twin Register aged between 7 and 97 years and dental data were obtained from pre-existing dental records. The outcome measures were a) summary indices of caries experience b) parameters representing trajectory in caries progression derived from longitudinal modelling and c) caries scores in groups of biologically similar tooth surfaces derived from hierarchical clustering of tooth surfaces (termed ‘caries clusters’).
Additive genetic factors explained between 49.1% and 62.7% of variation in caries scores, and between 50.0% and 60.5% of variation in caries trajectories. Seven caries clusters were identified which had estimates of heritability lying between 41.9% and 54.3%. Shared environmental factors were only important for some of these clusters and explained 16% of variation in fissure caries in molar teeth, but little variation in other clusters of caries presentation. The genetic factors influencing these clusters were only partially overlapping, suggesting that different biological processes are important in different groups of tooth surfaces, and that innate liability to some patterns of caries presentation may partially explain why groups of tooth surfaces form clusters within the mouth.
These results provide improved quantification of genetic factors in the aetiology of caries, provide new data about the role of genetics longitudinal changes in caries status and specific patterns of disease presentation and may help lay the foundations for personalized interventions in the future.