The majority of rapid maxillary expansion studies have reported the us
e of appliances with metal bands attached to the posterior teeth. Toot
h extrusion, dental tipping, and an increase in the vertical dimension
are often encountered, which may not coincide with treatment objectiv
es. Bonded appliances using interocclusal acrylic may control the vert
ical dimension and expand the maxillary halves in a more bodily and sy
mmetrical fashion. The purpose of this clinical trial was to determine
, by radiographic analysis, the differences between a conventional ban
ded expander (Hyrax) and a bonded acrylic expander. Fourteen patients
who exhibited a need for expansion were enrolled in the study. The res
ults suggest that the increase in the vertical dimension often seen wi
th the more conventional Hyrax appliance may be minimized or negated w
ith the bonded appliance. However, there appeared to be no significant
difference between the amount of dental tipping or symmetrical expans
ion between the two appliances, as previously theorized.