iOrtho: Expansion

Expansion has been part of orthopedic and orthodontic treatment for over 100 years. (Figs. 0a and 0b) In the last twenty-five years, more than five thousand articles have been published on maxillary expansion. In 2004, Daniel Turpin, editor of the AJODO reported that there was no clear consensus in the literature on the most efficient, effective, and stable methods to correct crossbite. The journal articles agreed basically, on one item – that is that some relapse is likely after maxillary expansion.

In this article, we will review some of the possible impacts of expansion on a child’s life. We will ponder timing of expansion treatment and its implications, and we will consider expansion’s role and timing in occlusal development, future occlusal harmony, and occlusal dysfunction. Maxillary (skeletal) expansion is typically accomplished using forces on teeth to transmit forces to the two lateral halves of the maxilla, although the literature gives us information about manual expansion directly to the bones (maxillae) of newborns, using the fingers or thumbs to accomplish maxillary suture widening just after birth. Because passage through the birth canal narrows the entire head transversely, just as the sutures of the cranium can “mold”, or slide over each other to safely narrow the skull during birth, so can the maxillary bones also be moved together. And when this happens, it is akin to squishing a beach ball together at the sides, transversely, which causes the beach ball’s shape to be pushed out in the sagittal, or front-back dimension, as well as to the vertical, or up-down dimension. When this happens to the cephalus head – during birth, it narrows the maxilla, making it more vertical and more deep sagitally. In the healthiest of situations, the function and ensuing development of the maxilla and head over the first few months of life widen the maxilla out transversely, undoing the narrowing of the birth process. Because the septum is connected to the maxilla superiorly and inferiorly, the septum is elongated and straightened by the widening of the maxillary growth and development, in the next few months and years.