The center of resistance of anterior teeth during intrusion using the laser reflection technique and holographic interferometry

The aim of this investigation was to define the location of the center of resistance of various consolidated units of the maxillary anterior dentition using a dry human skull when subject to intrusive forces. The laser reflection technique and the holographic interferometric technique were employed to measure the displacement of the dentition to the applied forces. The units studied consisted of (a) two central incisors, (b) four incisors, and (c) six anterior teeth. The incorporation of the lateral incisors into the upper incisor segment resulted in a small distal shift of the center of resistance (±2 mm). However, when the canines were included into this unit, the center of resistance shifted distally by a significantly larger amount (±7 mm). Increasing the magnitude of intrusive forces applied to the various units appeared to have no effect on the location of the center of resistance.