The impacted lower third molar and its relationship to tooth size and arch form. Eur J Orthod

SUMMARY The Reflex Metrograph was used to make measurements of tooth size and arch dimensions on lower casts of adult subjects with intact lower arches and no history of orthodontic treatment who had (a) bilaterally impacted lower third molars, and (b) bilaterally erupted lower third molars. Analysis showed the 'impacted ' group to have generally larger teeth and a greater degree of crowding than the 'erupted ' group. Differences in arch dimensions between the two groups were small but the impacted group tended to have longer arches with greater circumference, particularly in females