Midpalatal suture opening: a normative study.

This study of the average response to midpalatal suture opening revealed the following significant results: 1. Maxillary expansion was effected in all fifty-six cases, but the older patients with more rigid skeletal components experienced little orthopedic change. 2. The maxilla always moves downward and moves varying degrees, from slightly backward to sometimes significantly forward during suture opening. Full recovery usually occurs during stabilization. 3. Maxillary skeletal width can be expanded with no relapse in younger patients. However, older patients often lose much of the width increase that is achieved through palatal expansion. 4. In younger patients, the mandible permanently rotates open less than 1 degree.