...there is a method to model a parametric jawbone in FreeCAD by sweeping
several crosssections made by Sketcher-BSplines along a 3D-curve also made of Sketcher-Bsplines.
There are even more complex BSpline sections possible, to get a natural model.
The Sweepcurve is made of the Intersection of a horizontel and a vertical projection of the jaw geometry.
Essential is the controlled positioning of the crossections by Placement-operation to avoid twists.
The usage of Lattice2WB delivers a reliable Sweeppath. (thanks to freecad-heini).