Maxillary displacement due to scar tissue influence on quad-helix expansion treatment in unilateral cleft lip and palate patients: Finite element analysis

Introduction
Scar tissue may influence the outcomes of quad-helix expansion in unilateral cleft lip and palate (UCLP) patients, affecting the process of expansion and treatment efficacy.

Objectives
The study aimed to analyze the displacement of maxilla in UCLP patients due to the influence of forces from quad-helix, scar tissue, and upper lip using finite element analysis (FEA). Material and methods: A 3D model of maxilla obtained from cone beam computed tomography scans of UCLP patients, and a 3D model of quad-helix were developed and simulated using FEA software. First simulation was conducted by applying quad-helix expansion forces. Second simulation involved applying expansion forces from quad-helix, scar tissue, and upper lip tension. Maxillary displacements were observed in transverse, vertical, and sagittal directions. Data were analyzed descriptively.

Results
When quad-helix expansion force was applied, the major segment displacement in the transversal and sagittal directions was smaller than that of the minor segment. Conversely, when the force from the scar tissue and upper lip was applied, the minor segment displacement in the sagittal direction was greater than that of the major segment.

Conclusions
The greatest hindrance to maxillary displacement due to the influence of scar tissue and upper lip tension in quad-helix treatment for UCLP patients is found in the anterior region of the minor segment.