Dental and Alveolar Inclination after Asymmetric Rapid Maxillary Expansion in True Unilateral Posterior Crossbite Cases


  • Zehra İleri
  • Faruk Ayhan Başçiftçi

Received Date: 15.07.2010 Accepted Date: 20.08.2010 Turk J Orthod 2010;23(3):226-240


The objective of the present study was to evaluate maxillary dental and dentoalveolar changes in true unilateral posterior crossbite cases treated with asymmetric rapid maxillary expansion.

Subjects and Methods:

The study group comprised 38 patients in the permanent dentition divided into two groups as treatment (experimental) and control. In treatment group, for asymmetric rapid maxillary expansion, an acrylic bonded appliance was used. Orthodontic study models were obtained before RME (T1), after expansion (T2), and after retention period (T3) in treatment group and at the beginning of control and at the end of control in control group. A line of barium sulphate solution was drawn between the upper first molars on the models, and radiographs were taken. Buccal tipping of the molar crowns and alveolar processes were evaluated on the radiographic images of the models.


In the treatment group, there were statistically significant increases both after expansion (11.22°) and retention (9.65°) periods in the alveolar inclination angle (β) (p<0,001). There was an statistically significant increase (3.71°) only after expansion in the tipping angle of the first molar of non-crossbite side (Gα) (p<0,05), while there was no significant change in the tipping angle of the first molar of crossbite side (Dα) after the RME treatment (p>0,05).


The asymmetric rapid maxillary expansion with a bonded RME appliance with full occlusal coverage of all upper teeth was found to be effective in correcting true unilateral posterior crossbites. The tipping of the first molars can be relatively decreased by this appliance.

Keywords: Asymmetric expansion, Dentoalveolar inclination, Bonded RME appliance