This systematic review evaluates long-term dental arch changes after rapid maxillary expansion treatment on orthodontic patients with constricted arches. Clinical trials that assessed dental arch changes through measurements on dental casts or cephalometric radiographs were selected. No patients with surgical or other simultaneous treatment during the active expansion period were accepted. Electronic databases were searched with the help of a senior Health Sciences librarian. Original articles were retrieved from the selected abstracts, and their references were also scanned for possible missing articles. Forty-one articles met the initial inclusion criteria, but 35 were later rejected because they lacked a control group or only evaluated dental changes or used a semirapid technique. Some of them also lacked a reported measurement error. From the remaining articles, two did not report a long-term evaluation. From the final four articles, two measured changes through dental casts and two assessed changes through radiographs (one through lateral cephalometric radiographs and one through posteroanterior radiographs). Similar maxillary molar and cuspid expansion could be found in adolescents and young adults. Significantly less indirect mandibular molar and cuspid expansion was attained in young adults compared with adolescents. A significant overall gain in the maxillary and inandibular arch perimeter was found in adolescents. More transverse dental arch changes were found after puberty as compared with before, but the difference may not be clinically significant. No anteroposterior dental changes were found on lateral cephalometric radiographs.