Determining the osteotomy pattern in surgically assisted rapid maxillary expansion in a unilateral palatal cleft: a finite element model approach.

OBJECTIVES: To evaluate the stress pattern in the craniofacial skeleton in a patient with unilateral cleft deformity of the secondary palate and alveolus in response to various techniques of surgically assisted rapid maxillary expansion (SARME).

MATERIALS AND METHODS: Three patient-specific composite skull models were developed for finite element model analysis. The details of the modeling procedure have been described in Part I of this series. The finite element analysis was performed on each model with a specified SARME technique in combination with RME using Abaqus (6.7).

RESULTS: The ideal form of surgery in SARME for patients with unilateral cleft deformity of the secondary palate and alveolus would be complete unilateral LeFort I with pterygoid dysjunction in combination with midpalatal split, followed by isolated midpalatal split and zygomatic buttress osteotomies.

CONCLUSIONS: A more invasive SARME technique can significantly reduce the resultant stresses. However, this benefit should be weighed against the risk of increasing complications associated with more extensive surgeries. When a more conservative surgical technique is selected, it would be preferable to perform a midpalatal split rather than zygomatic buttress osteotomies, as indicated by the stress-strain distribution and displacement pattern associated with different SARME techniques.