Orthodontic and orthopedic expansion of the transverse dimension: A four decade perspective

Abstract

This paper describes four decades of research carried out at the University of Michigan that has investigated the clinical alteration of the transverse dimension of the face, with specific attention given to orthodontic and orthopedic treatment of patients in the early mixed dentition. The results of a series of clinical studies beginning in the late 1970s are described that consider the etiology of dental crowding as well as treatment effects produced by expansion in the late mixed/early permanent dentition and the early mixed dentition. A treatment protocol for early treatment is described that includes the lower Schwarz appliance, a bonded acrylic splint expander and the placement of anterior brackets. A series of retrospective and prospective studies are presented, including a study investigating the spontaneous improvement of Class II malocclusion following increases in the transverse dimension. The effect of maintaining or increasing anterior arch length on subsequent mandibular second molar eruption is evaluated. The ideal timing for rapid maxillary expansion is before puberty. An individual assessment of the midpalatal suture using cone-beam computed tomography (CBCT) images can be useful when making a clinical decision between conventional and surgically assisted RME, especially for adolescent and young adult patients.