Evaluation of Stress in the Maxillary Complex of a Unilateral Cleft Lip and Palate on Simulated Occlusal Loading Using Finite Element Analysis.

BACKGROUND

In individuals with a unilateral cleft lip and palate, there routinely exists an abnormality of the facial skeleton in all three planes transverse, sagittal and coronal. Skeletal and facial asymmetry is pronounced in the anterior part of the maxilla with a smaller maxillary width and height on the cleft side. As a mechanical stimulant, occlusal forces and the resulting stress and strain distribution within the skeletal components lead to strain-induced bone remodeling. This study was done to observe the stress distribution pattern and displacement within the maxillary complex in a complete unilateral cleft lip and palate individual when subjected to simulated occlusal forces, using a three-dimensional finite element analysis.

MATERIAL AND METHODS

A three-dimensional finite element model of the maxillary complex of a unilateral cleft lip and palate individual was developed from sequential computed tomography scan images processed at 1-mm intervals. ANSYS™ 14.0 and MIMICS™ software were used for the same. Masseter forces of 300 N were applied at the zygomatic arch bilaterally, and occlusal loads of 100 N were applied vertically onto the framework surface at different locations to simulate occlusal loading. The displacement and von Mises stresses in different planes were studied on different nodes at various anatomical points within the maxillary complex.

RESULTS

The unilateral cleft lip and palate led to a non-uniform, asymmetric stress distribution pattern within the maxillary complex: intensified on the non-cleft side and weakened on the cleft side. An asymmetric displacement pattern was noted between the cleft and non-cleft sides.

CONCLUSIONS

The results implied that an individual born with a complete unilateral cleft lip and palate would be expected to have an asymmetric facial development between the non-cleft and cleft sides as a result of an asymmetric occlusal loading pattern.