Abstract
Introduction: Although cleft palate repair during early childhood improves facial appearance and functional development, it may cause maxillary deficiency. Maxillary protraction with the expansion is recommended to treat this deficiency where both the amount and direction of forces have an influence on the displacement of craniofacial structures. Finite Element analysis is a computer-based simulation to analyze stress and deformation induced by forces at any point or direction. Studies using FEM to analyze the effect of maxillary protraction reported that different directions and points of application of protraction forces influence the distribution of stress and pattern of displacement. The aim of this study was to simulate the different magnitudes of protraction forces with and without expansion at variable angulations in a UCLP model to analyze stress and displacement.
Materials and Methods: Ethical clearance was obtained from the ethics committee of our university to carry out the study. The DICOM files of CT scan of a patient with UCLP with a cleft on the left side were imported into MIMICS software version 18 (Materialise NV, Leuven, Belgium) for construction of FE model. The finite element model consisting of 1,85,620 tetrahedral shaped elements and 49,807 nodes was created. Two types of protraction forces (P1= 300 g/side and P2= 600 g/side) were applied from the middle of the clinical crown on the buccal side of the first premolars at +20°, 0°, and -20° angulation to the occlusal plane. The Expansion force was applied to the middle of the crown length on the palatal side of the first premolars and the first molars with the following distribution of forces - 50% on the premolar region and 50% on the molar region.
Twelve clinical situations consisting of protraction only [P1, +20°, P1, 0°, P1, -20°, P2, +20°, P2, 0°, and P2, -20°, (n=6)] and protraction with expansion [P1, E, +20°, P1, E, 0°, P1, E, -20°, P2, E, +20°, P2, E2, 0°, and P2, E2, -20°, (n=6)] were simulated using. 23 marker nodes.
Results: Initial displacement and von Mises stress for only protraction, and protraction with expansion were analyzed Canonsburg. along X-axis (transverse plane), Y-axis (sagittal plane), and Z-axis (vertical plane). using ANSYS 19, Inc.
Initial displacement and stress increased with an increase in protraction forces and were more for protraction with expansion as compared to protraction only
- An asymmetric pattern of protraction with symmetric forces
- +20° protraction force produced maximum displacement and stress as compared to 0°, or -20°
- In the transverse plane, protraction with expansion produced more displacement than protraction only
- In the sagittal plane, the length of PP increased more with protraction only as compared to protraction with expansion
- In the vertical plane, protraction with expansion and downward angulation, and less protraction force reduced CCW rotation
- The craniofacial structures articulated with other bones exhibited more stress than on the extremities
Conclusions: An asymmetric pattern of displacement is more on the cleft than noncleft side and stress is more on the noncleft than the cleft side of UCLP