The contribution of genetics to dental caries, oral habits and occlusal traits in Turkish twins: A comparative study

OBJECTIVE: The aims of this study were to investigate and compare the prevalence of dental caries and the frequency of oral habits, molar relationships and occlusal traits between children of multiple births, and singletons, and to determine the relative contributions of genetics and environmental factors to these parameters by using twin study design. METHODS: The study group consisted of 345 multiple births (34 monozygotic and 122 dizygotic twin pairs, 11 sets of triplets) and 345 singletons between the ages of 2 and 17. The prevalence of dental caries, and the frequency of tooth brushing, the children’s oral habits, molar relationships, and occlusal traits were recorded. RESULTS: The percentage of children who brushed their teeth more than twice daily was statistically significantly higher in multiple births than in singletons. Higher correlation coefficients were found in dental caries index, except for decayed, filled (df) (2–5 age group) and filled (f) (6–11 age group), in the monozygotic twin pairs compared to those in the dizygotic twin pairs. In children between the ages of 6 and 11 years, mouth breathing, bruxism, lip biting, and pencil biting were higher in singletons than in children of multiple births. There were statistically significant differences between children of multiple births and singletons, with increased overjet in the 2–5 year age group being observed. CONCLUSION: When analyzing these parameters, environmental factors must also be investigated. Due to the low incidence of twin births, longitudinal follow-up studies with more twin pairs are necessary to determine whether these results are generalizable.