Index for Measurement of Lower Labial Segment Crowding

Abstract

A technique has been developed to measure crowding of the lower labial segment which involves measurement of photographic enlargements produced from models of the lower arch. The width of the individual six anterior teeth was measured following specific criteria and the space available in the labial segment was measured with a flexible ruler. The index was expressed as the ratio of the sum of the individual tooth widths to the space available. The index was found to be reproducible both within and between examiners with a standard deviation of 0·015 to 0·02 when the index was between 0·89 and 1·24. The index was also found to have a high degree of correlation when compared with subjective ranking.