The Genetic and Environmental Contributions to Variation in the Permanent Dental Arch Form: A Twin Study

Abstract

Objective- The objective of this study was to assess the relative contribution of genes to shape variation in the permanent dental arches.

Material and methods- Twin records and dental casts from 64 monozygotic and 38 dizygotic twins were evaluated. A three-dimensional scanner was used to scan dental casts, and markings were positioned on the cusp tips and incisal edges of molars, premolars, and canines. Shape variation was examined using main components analysis and Procrustes superimposition. The spherical form covariation between arches was evaluated using two-block partial least-squares approach. Using the standard assumptions of the twin model, structural equation modelling was used to break down observed shape variation into hereditary and environmental components.

Results- Within shape space, most of the variation in maxillary and mandibular arches exhibited moderate to high heritability (h2 = 0.61-0.74). Maxillary and mandibular dental arches had strong and significant shape covariation, with high heritability in their reciprocal influences on shape (h2 = 0.72-0.74; rpls coefficient = 0.87; P <0.05).

Conclusion- In this cohort, dental arch shape variation was predominantly influenced by genetic factors. High covariation and heritability were observed between the maxillary and mandibular dental arches.