BACKGROUND Lengthening the maxillary dental arch as a treatment approach for patients with maxillary deficiency and dental crowding is seldom reported. The purpose of this study was to assess dental and skeletal changes in the maxilla in the correction of maxillary deficiency associated with a retruded maxillary arch using a surgically assisted rapid maxillary anterior-posterior expansion appliance. METHODS Predistraction and postraction lateral cephalometric and periapical radiographs and maxillary dental casts of six young adolescents (four boys, two girls, mean age 11 years, 2 months) were examined. These patients received a maxillary anterior segmental osteotomy and distraction osteogenesis with an anteroposteriorly oriented Hyrax expansion appliance based on the biological principles of bone distraction. RESULTS The retruded dental arch and dental crowding were successfully corrected. Significant forward movement of the point anterior nasal spine, point A, central incisors and first premolars was noted. The maxillary dental arch depth increased an average of 4.2 mm while the arch width remained unchanged. In total, 11.5 mm of dental space was created in the maxillary arch which was sufficient to resolve dental crowding. New bone formation along the distraction site was observed three months after distraction. CONCLUSIONS The use of maxillary anterior segmental osteotomy combined with a Hyrax expansion distraction appliance was effective in arch lengthening and creation of dental space. An overcorrection in this interdental distraction osteogenesis could be a good treatment option for children with maxillary deficiency combined with crowded maxillary dentition.