Genetic, Epigenetic and Environmental Influences on Human Tooth Size, Shape and Number

Abstract

Studies of twins are helping to unravel the roles of genetic, epigenetic and environmental influences on human tooth size, shape and number. There is a relatively strong genetic contribution to variation in these dental phenotypes but comparisons between monozygotic cotwins are also highlighting the roles of environmental and epigenetic factors. Furthermore, by viewing the dentition as a complex adaptive system, with multiple interacting components, a clearer picture is emerging of how common dental anomalies develop and are associated with one another. This article concentrates on providing a synthesis of relevant findings and concepts about variation in the human dentition at a phenotypic level. We focus on patterning within the dentition and dental asymmetry, as well as emphasising the importance of assessing the magnitude of errors when measuring or scoring dental features. We also provide links to several articles published in the Encyclopedia of Life Sciences that cover the molecular aspects of dental development. Key Concepts: There are distinct patterns of variation within the human dentition that conform to ‘morphogenetic fields’. Patterns of phenotypic variation correspond with the relative amount of time that each tooth germ spends in the soft tissue phase before mineralisation. A unifying aetiological model, incorporating thresholds, serves to explain the relationships between tooth size, shape and number in males and females. Tooth size variation shows a relatively strong genetic component but epigenetic and environmental factors can also contribute to phenotypic variation. Interrelationships exist between dental crown size and morphological dental features, such as the Carabelli trait. Discordance in the expression of missing or extra teeth between monozygotic cotwins indicates involvement of epigenetic influences on dental development. Studies of dizygotic opposite sex twins indicate that hormonal influences in utero can influence dental development. The magnitude of fluctuating dental asymmetry reflects the effects of epigenetic and environmental influences during development. Dental development is a multilevel process involving interacting genetic, epigenetic and environmental factors over an extended period. The dentition fulfils the characteristics of a complex adaptive system.

Impact of genetics on third molar agenesis

“…Townsend et al . proposed that they could reflect different responses of odontogenic cells to minor variations in the spatial and temporal expression of local signalling molecules passing between cells during development and can lead to quite major differences in the final appearance of the dentitions 36 .…”

Genetic, Epigenetic, and Environmental Influences on Dentofacial Structures and Oral Health: Ongoing Studies of Australian Twins and Their Families

“…Apart from using the traditional twin approach, involving comparisons of MZ twin pairs and DZ twin pairs, we have also used the MZ co-twin design to investigate genetic and environmental influences on dental traits where one twin shows a feature and the other shows different expression or does not display the trait at all (Townsend & Brook, 2008). We have also looked at tooth size in twin pairs and found evidence for a possible male hormonal influence on dental development of females in utero (Ribeiro et al, 2012).…”

“…Teeth, faces, and fingerprints are particularly suitable for studies of symmetry and asymmetry, and we have been particularly interested in studying the fascinating feature of mirror-imaging of dentition or different expression (Mihailidis et al, 2012, in press; Townsend & Brook, 2008; Townsend & Martin, 1992; Townsend et al, 1986).…”

Frequency and variability of five non metric dental crown traits in the permanent maxillary dentitions of a racially mixed population from Bengaluru, Karnataka

“…Bioarchaeology is the contextual study of the biology, culture and evolution of human populations using skeletal remains interpreted within archaeological, historical, and contemporary problem orientations. [1,2] Bioarchaeology has close connections with skeletal biology and forensic science and emerged as a popular field during the 1970s in the light of the New Archaeology. [3,4] One of the disciplines within bioarchaeology is dental anthropology.…”