An examination of proportional root lengths of the mandibular canine and premolars near the time of eruption

Abstract

To make treatments more efficient, orthodontists require a more precise means of estimating tooth eruption. The purpose of this article was to extend the information derived from dental staging techniques by incorporating direct measurements of root lengths for 3 mandibular teeth: the canine and the 2 premolars. The full sample consists of 227 panoramic films from 77 female patients and 229 films from 74 male patients treated at a practice in Texas. A subsample of paired preeruption and posteruption films was examined in greater detail (46 subjects for the canine, 42 for the first premolar, and 46 for the second premolar). Canines will most likely have root length ([root length/total tooth length] × 100) of approximately 70% and premolars will have approximately 65% near the time of alveolar eruption. In addition, the walls of the root canal will probably approach a parallel configuration at the time of eruption. The percentage of root length, along with root canal parallelism, should allow improved prediction of eruption timing.