THE EDITOR'S CORNER

In my experience, labially impacted upper cuspids were less responsive to movement than palatally impacted cuspids and I could never figure out why. A reasonable explanation is given in the current installment of the Bio-Progressive Therapy series.

I was always trying to move labially impacted upper cuspids downward and forward. I should have realized that I was trying perhaps the most difficult of all movement--to move a tooth continually through the length of the labial cortical plate. To compound the error, as the tooth failed to move, I applied more pressure assuring that it would not move through the dense, avascular, cortical bone.

In contrast to this, palatally impacted upper cuspids usually responded favorably and quickly. Undoubtedly, the reason was that the necessary movement usually carried these teeth through less dense, vascular, trabecular bone.

We have tended to ascribe failure with impacted cuspids to ankylosis and this may occasionally have been the cause. However, the nature of bone looks like a more logical culprit. Intractable palatally impacted cuspids are probably impeded by teeth and/or by the palatal cortical plate.

In either case, labial or lingual, if the orthodontist were present at the surgical uncovering of the tooth, he could make valuable suggestions about channeling of cortical bone and valuable decisions about the direction of pull; and if one must move through substantial cortical bone, he must be prepared to use much less force and more time.