Lower incisor space analysis: a contrast of methods.

Two current methods to assess spacing-crowding among lower anterior teeth are described and contrasted. These are the anterior space analysis of Merrifield and the irregularity index of Little. There is only a modest correlation between these methods (rs = +0.53) because they provide complementary information; space analysis is more attuned to tooth displacements while the irregularity index is susceptible to axiversions. Cases illustrating major divergences between the two methods are illustrated.