Finite element method comparison of murine mandibular form differences.

The differences of adult female murine mandibular form between two inbred strains of mice (BALB/cBy and C57BL/6By) were analyzed by use of the finite element method (FEM). In the present instance, this method overcomes the conceptual and methodologic constraints of both craniometry and roentgenographic cephalometry by providing two-dimensional, reference-frame-invariant, independent comparisons of the size, shape, and location of the point continua enclosed within the boundaries for each local, finite element into which the mandible was discretized. At the present scale of observation, it is suggested that the FEM kinematic descriptions of form comparisons can be correlated with dynamic interpretations offered by the functional matrix hypothesis, i.e., that certain discrete, causal relationships exist between the continuum form of single elements and the form, or function, of anatomic structures associated with these elements. It is concluded that, in addition to its previously demonstrated use in the analysis of growth, the finite element method seems well suited for comparisons of form.