Odontogenic polarity and Butler's field theory

Tooth shape potential resides in those ectomesenchymal cells that colonise the presumptive jaws prior to the commencement of odontogenesis. Support for Butler's field theory as applied to the human dentition hinges on the observation that distal teeth within each morphogenic class are the most variable. This variability, it has been argued, reflects a decrease in the concentration of field substance with increased distance from the polar teeth. In contrast to the above, it is suggested here that tooth size variability should be related to the length of time spent in the soft tissue stage prior to calcification. It is argued that a long soft tissue stage will result in a variable phenotype and vice versa. Odontometric variability of distal teeth is thus unrelated to morphogenetic field concentrations and hence fails to support Butler's field theory.