Finite-Element Biomechanical-Simulated Analysis of the Nasolabial Fold.

[BACKGROUND] Nasolabial fold (NLF) is an important anatomic sign of facial aging. However, the dynamic biomechanical relationships between the facial mimetic muscles (FMMs) and the NLF remain unclear.

[OBJECTIVE] This study aimed to investigate the dynamic biomechanical relationships between the FMM and various NLF by finite-element analysis (FEA).

[METHODS] The 3-dimentional computer-aided design (3D CAD) model of the skin-muscle-maxillofacial bone in the NLF was established by using the engineering design module of the Computer-Aided 3-dimensional Interactive Application (CATIA) software. This CAD model was then imported into the Hypermesh software to set element type, mesh, and material properties. Finally, the 3D FEA model of the skin-muscle-maxillofacial bone in the NLF was generated, and then exported and uploaded into the Abaqus software with HM format for mechanical force loading and biomechanical analysis.

[RESULTS] A 3D FEA model of the skin-muscle-maxillofacial bone in the NLF was successfully established by using the Mimics, Geomagic Studio, CATIA, Hypermesh, and Abaqus softwares. This FEA model had a good geometrical resemblance and good biomechanical properties. This provided an ideal biomechanical model for the study of deformation and the biomechanics of soft tissues, such as the NLF. The FEA was applied to the biomechanical simulation of the NLF. We established five effective FEA models to study the dynamic biomechanical relationships between the NLF and the FMM. The dynamic biomechanical relationships between the NLF and the FMM were preliminarily determined by computer simulating different types of mechanical force loadings.

[CONCLUSION] The FEA is an effective method to simulate the dynamic biomechanical relationships between the NLF and the FMM. Through the FEA simulation described in this study, we could preliminarily conclude that the formation of different types of NLF is mainly due to the coordinated contraction of various FMM. Moreover, not all FMM are involved in all types of NLF. According to the results of the FEA simulations in this study, it is worthwhile considering investigating the role of botulinum toxin in improving the morphology of the NLF in the near future.