Morphogenetic fields within the human dentition: A new, clinically relevant synthesis of an old concept

Abstract

This paper reviews the concept of morphogenetic fields within the dentition that was first proposed by Butler (Butler PM. Studies of the mammalian dentition. Differentiation of the post-canine dentition. Proc Zool Soc Lond B 1939;109:1–36), then adapted for the human dentition by Dahlberg (Dahlberg AA. The changing dentition of man. J Am Dent Assoc 1945;32:676–90; Dahlberg AA. The dentition of the American Indian. In: Laughlin WS, editor. The Physical Anthropology of the American Indian. New York: Viking Fund Inc.; 1951. p. 138–76). The clone theory of dental development, proposed by Osborn (Osborn JW. Morphogenetic gradients: fields versus clones. In: Butler PM, Joysey KA, editors Development, function and evolution of teeth. London: Academic Press, 1978. p. 171–201), is then considered before these two important concepts are interpreted in the light of recent findings from molecular, cellular, genetic and theoretical and anthropological investigation. Sharpe (Sharpe PT. Homeobox genes and orofacial development. Connect Tissue Res 1995;32:17–25) put forward the concept of an odontogenic homeobox code to explain how different tooth classes are initiated in different parts of the oral cavity in response to molecular cues and the expression of specific groups of homeobox genes. Recently, Mitsiadis and Smith (Mitsiadis TA, Smith MM. How do genes make teeth to order through development? J Exp Zool (Mol Dev Evol) 2006; 306B:177–82.) proposed that the field, clone and homeobox code models could all be incorporated into a single model to explain dental patterning. We agree that these three models should be viewed as complementary rather than contradictory and propose that this unifying view can be extended into the clinical setting using findings on dental patterning in individuals with missing and extra teeth. The proposals are compatible with the unifying aetiological model developed by Brook (Brook AH. A unifying aetiological explanation for anomalies of tooth number and size. Archs Oral Biol 1984;29:373–78) based on human epidemiological and clinical findings. Indeed, this new synthesis can provide a sound foundation for clinical diagnosis, counselling and management of patients with various anomalies of dental development as well as suggesting hypotheses for future studies.

Morphological variation of the maxillary lateral incisor

“…Butler [28] was a pioneer in describing the concept of morphogenetic fields to account for the gradients in size and shape of teeth evident in the dentitions of different species (reviewed by Townsend et al [29]). Dahlberg [30,31] adapted Butler's concepts to the human dentition and proposed that there was a field of influence operating on each of the tooth classes.…”

Elucidating the evolution of hominid dentition in the age of phenomics, modularity, and quantitative genetics

“…While the field and clone models of tooth development have a rich academic history, including recent updates by Townsend et al (2009a), these models were derived from patterns of phenotypic data that are hard to reconcile specifically with our current understanding of developmental genetics. Therefore, it is perhaps worthwhile to set these historical frameworks aside and focus on evidence generated from quantitative genetic analyses.…”

Expression of cytokeratin 8, vimentin, syndecan-1 and Ki-67 during human tooth development

“…Morphogenesis of different teeth is a consequence of spatio-temporal appearance of cell proliferation, apoptosis and cell differentiation, as well as cell-to-cell and cell-matrix interactions Townsend et al 2009). Firstly observed developmental process during odontogenesis is cell proliferation, which is usually visualized by the Ki-67 nuclear antigen.…”