To digitize the models, 14 points, each representing the
midpoint of the bracket or tube on the tooth, were recorded
on each arch. To mark the upper anatomical y-axis, two points
on the midpalatal raphe were captured (Ferrario et al., 1997;
BeGole, 1980). Several MATLAB computer programs were
created and used to capture landmarks. To eliminate the effect
of tooth irregularities in the dental arches, the 14 landmark
points representing the teeth were fitted with a mathematical
descriptor that produces a smooth and representative curve.
Fourth- and sixth-order polynomials were sufficiently flexible
to approximate the dental arch form. These mathematical
functions are monotonic in nature, produce a regular curve,
and distribute the error evenly around the arch