Comparative Finite Element Analysis of the Biomechanical Stability of 2.0 Fixation Plates in Atrophic Mandibular Fractures
ABSTRACT The objective of the present study was to conduct a computational, laboratory-based comparison of the biomechanical stability of 2.0 fixation locking plates with different profiles in Class III atrophic mandibular fractures using 3-dimensional finite element analysis.
Three-dimensional finite element models simulating Class III atrophic mandibular fractures were constructed. The models were divided into 4 groups according to plate thickness (1.0, 1.5, 2.0, and 2.5 mm). Fractures were simulated in left mandibular bodies, and 3 locking screws were used on each side of each fracture for fixation. Bite forces of approximately 63 N were simulated in the incisor and molar regions of the mandibles in finite element models.
The level of compressive strain on the bone around the screw was within the physiological limit. No significant difference was observed in the displacement of bone segments in the fracture region. Von Mises stress was higher during simulated bites in the molar region for plates with thicknesses of 1.0 mm. Plate tension values were below the level required for permanent deformation or fracture in all models. The 2.5-mm-thick plate presented better biomechanical performance than all other plates. The 2.0-mm-thick plate also showed satisfactory results and adequate safety limits.
Large-profile (2.0-mm-thick) locking plates showed better biomechanical performance than did 1.0- and 1.5-mm-thick plates and can be considered an alternative reconstruction plate for the treatment of Class III atrophic mandibular fractures.
- SourceAvailable from: George K Sándor
[Show abstract] [Hide abstract]
- "A search of the prevalent literature did not provide information regarding muscle forces in mandible post-resection. To circumvent this lack of information, standard muscle forces (Korioth et al., 1992; Vajgel et al., 2013) were applied to determine the reaction force in the molars and then designated as chewing force. Subsequently, the boundary conditions were changed from muscle forces to zero displacement in all directions and molar chewing force applied. "
ABSTRACT: Large mandibular continuity defects pose a significant challenge in oral maxillofacial surgery. One solution to this problem is to use computer-guided surgical planning and additive manufacturing technology to produce patient-specific reconstruction plates. However, when designing customized plates, it is important to assess potential biomechanical responses that may vary substantially depending on the size and geometry of the defect. The aim of this study was to assess the design of two customized plates using finite element method (FEM). These plates were designed for the reconstruction of the lower left mandibles of two ameloblastoma cases (patient 1/plate 1 and patient 2/plate 2) with large bone resections differing in both geometry and size. Simulations revealed maximum von Mises stresses of 63MPa and 108MPa in plates 1 and 2, and 65MPa and 190MPa in the fixation screws of patients 1 and 2. The equivalent strain induced in the bone at the screw-bone interface reached maximum values of 2739 micro-strain for patient 1 and 19,575 micro-strain for patient 2. The results demonstrate the influence of design on the stresses induced in the plate and screw bodies. Of particular note, however, are the differences in the induced strains. Unphysiologically high strains in bone adjacent to screws can cause micro-damage leading to bone resorption. This can adversely affect the anchoring capabilities of the screws. Thus, while custom plates offer optimal anatomical fit, attention should be paid to the expected physiological forces on the plates and the induced stresses and strains in the plate-screw-bone assembly.Journal of Biomechanics 11/2013; 47(1). DOI:10.1016/j.jbiomech.2013.11.016 · 2.75 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The aim of the presented work is compare a two different way of prescribing muscles and chewing force boundary condition. First variant of boundary condition consider muscle forces and their direction taken from literatures. Second variant of boundary condition consider muscles modeled as finite elements connecting lower jaw and skull together. At second variant a muscles material characteristic of Young ́s modulus was changed in range from 1e4 MPa to 2,1e5 MPa. Models of living tissues were created on base of CT images and modeled in 3D CAD software SolidWorks. Calculations were computed in the finite element software ANSYS. Material models were considered as homogenous, isotropic and linearly elastic for all parts. First, both variants of boundary condition were analyzed separately and after that, selected variables (as muscle forces and muscle direction scale factors) from both variant were compared together.Applied Mechanics and Materials 09/2013; 436:225-264. DOI:10.4028/www.scientific.net/AMM.436.255 · 0.15 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: As fractures of the supraorbital region are far less common than midfacial or orbital fractures, a study was initiated to investigate whether fist blows could lead to fractures similar to those often seen in the midface. A detailed skull model and an impactor resembling a fist were created and a fist blow to the supraorbital region was simulated. A transient finite element analysis was carried out to calculate von Mises stresses, peak force, and impact time. Within the contact zone of skull and impactor critical stress values could be seen which lay at the lower yield border for potential fractures. A second much lower stress zone was depicted in the anterior-medial orbital roof. In this simulation a fist punch, which could generate distinct fractures in the midface and naso-ethmoid-orbital region, would only reach the limits of a small fracture in the supraorbital region. The reason is seen in the strong bony architecture. Much higher forces are needed to create severe trauma in the upper face which is supported by clinical findings. Finite element analysis is the method of choice to investigate the impact of trauma on the human skeleton.Head & Face Medicine 04/2014; 10(1):13. DOI:10.1186/1746-160X-10-13 · 0.87 Impact Factor