Biomechanical analysis of rapid maxillary expansion in the UCLP patient.

This study was designed to investigate the biomechanical effects of rapid maxillary expansion (RME) in the patient with unilateral cleft lip and palate (UCLP). A finite element model of a patient's craniofacial complex with UCLP was created using data from spiral computed tomographic (CT) scanning. A transversal displacement with a magnitude of 5mm was applied on the maxillary premolar and first permanent molar crown of the model simulating the clinical situation. The stress and deformation within the craniofacial complex were then calculated and analyzed during 0.25- and 5-mm expansions. The corresponding orthodontic forces on each loaded tooth were also calculated. Obtained results revealed the biomechanical performance of the craniofacial complex with UCLP undergoing RME, including the distribution pattern of the stress and displacement, the transmission and dissipation of the orthodontic force, the stress level and the magnitude of the orthodontic force. All these findings could help us better comprehend the biomechanical mechanism of RME in the UCLP patient and provided theoretic data for optimizing surgical assisted RME in clinic.