Physiologic Tooth Migration

¹ Forsyth Dental Center, Harvard School of Dental Medicine, Boston, Massachusetts

Mesial tooth migration of permanent first molars, as well as the permanent and deciduous canines, has been studied in its projection on the midsagittal plane by means of the Korkhaus symmetrograph.

From a total of 184 individuals, serial dental casts of only 20 (7 males and 13 females) met the requirements of optimal dental health and qualitative excellence.

With reference to the rugae, the migration of the permanent first molar after its emergence up to eighteen years of age reached a mean value of 4.0 mm. mesial drift of the deciduous and permanent canines (five to eighteen years) averaged 3.1 mm.

Mesial movement of the permanent first molar occurred mainly during the eruption of the posterior or cheek teeth but continued after the second molar was present (mean 1.37 mm.).

The migration of the deciduous canine was also generally in mesial direction, except that slight (0.5-2.0 mm.) distal drift was observed in 4 out of 13 individuals during the eruption of the permanent lateral incisor. Following the eruption of the permanent canine, the greatest movement was noted. It continued after all permanent teeth were present (excepting M₃).

The findings pertain only to maxillary teeth, and they constitute an attempt to initiate mesial tooth migration. The data should be accepted within the limitations of the method used and with the small number of serial casts suitable for study.