Three-Dimensional Finite Element Analysis of Different Plating Techniques for Unfavorable Mandibular Angle Fractures

Finite Element Analysis of New Modified Three-dimensional Strut Miniplate versus Conventional Plating in Mandibular Symphysis and Angle Fractures - An In vitro Study

Introduction

Mandibular fractures are common injuries during maxillofacial trauma, and currently, open reduction and internal fixation are considered gold-standard treatments. There is a wide discussion about which plates give the best outcomes. Hence, we are conducting a biomechanical comparison of two plates for mandibular symphysis and angle fracture with finite element analysis (FEA). The aim of this study was to do a comparative study of FEA between the conventional and our new modified three-dimensional (3D) strut miniplate in mandibular fractures at symphysis and angle regions.

Materials and Methods

Finite element models of symphyseal and angle fractures of the mandible were developed. Each fracture model was then realigned and fixed by the conventional method 2.0 mm system, and our modified 3D strut plating method 2.0 mm system followed by the analysis of various stresses developed in plates and mandibular fracture area after application of load was observed in the study.

Results

The modified 3D strut plating system with 2.0 mm miniplates is significantly better in preventing displacement of fracture segments by better distribution of forces compared to the conventional plating system. Rest of the parameters were within the permitted limits.

Discussion

Modified 3D strut plating method was reasonably effective and superior in managing force-displacement compared to the conventional method of fixation for comminuted and unfavourable mandibular symphyseal fracture and angle fracture.

Experimental validation of finite element simulation of a new custom-designed fixation plate to treat mandibular angle fracture

BACKGROUND

The objective of the study was to validate biomechanical characteristics of a 3D-printed, novel-designated fixation plate for treating mandibular angle fracture, and compare it with two commonly used fixation plates by finite element (FE) simulations and experimental testing.

METHODS

A 3D virtual mandible was created from a patient's CT images as the master model. A custom-designed plate and two commonly used fixation plates were reconstructed onto the master model for FE simulations. Modeling of angle fracture, simulation of muscles of mastication, and defining of boundary conditions were integrated into the theoretical model. Strain levels during different loading conditions were analyzed using a finite element method (FEM). For mechanical test design, samples of the virtual mandible with angle fracture and the custom-designed fixation plates were printed using selective laser sintering (SLS) and selective laser melting (SLM) printing methods. Experimental data were collected from a testing platform with attached strain gauges to the mandible and the plates at different 10 locations during mechanical tests. Simulation of muscle forces and temporomandibular joint conditions were built into the physical models to improve the accuracy of clinical conditions. The experimental vs the theoretical data collected at the 10 locations were compared, and the correlation coefficient was calculated.

RESULTS

The results show that use of the novel-designated fixation plate has significant mechanical advantages compared to the two commonly used fixation plates. The results of measured strains at each location show a very high correlation between the physical model and the virtual mandible of their biomechanical behaviors under simulated occlusal loading conditions when treating angle fracture of the mandible.

CONCLUSIONS

Based on the results from our study, we validate the accuracy of our computational model which allows us to use it for future clinical applications under more sophisticated biomechanical simulations and testing.

Biomechanical comparison of the All-on-4, M-4, and V-4 techniques in an atrophic maxilla: A 3D finite element analysis

BACKGROUND

Patients with severely atrophied jaws can be challenging in implantology. The All-on-4 treatment concept eliminates advanced augmentation procedures in highly resorbed ridges by preserving the relevant anatomic structures. In addition, the inclination of the distal implants enables the placement of longer implants. Hence, tilting the anterior implants allows longer implant placement, in line with the distal implants of the All-on-4 concept. This study compared the biomechanical aspects of the standard All-on-4 treatment concept with the M-4 and V-4 techniques.

METHODS

A three-dimensional model of an edentulous maxilla was created to perform three-dimensional finite element analysis. Three different configurations (All-on-4, M-4, and V-4) were modeled by changing the tilt angle of the anterior implants. In each model, to simulate a foodstuff, a solid spherical material was placed on the midline of the incisors and the right first molar region, separately applying an occlusal load of 100 Newtons. The maximum principal stress and minimum principal stress values were acquired for cortical bone, and von Mises stress values were obtained for ductile materials.

RESULTS

According to the present study's findings, although there were no considerable differences among the models, in general, the All-on-4 group demonstrated slightly higher stresses and the M-4 and V-4 group showed lower stresses.

CONCLUSION

M-4 or V-4 configurations may be used in cases of severely atrophied anterior maxillae to achieve better primary stabilization.

[Biomechanical study of cystic lesions of the mandible based on a three-dimensional finite element model]

OBJECTIVE

To analyze the biomechanics of cystic lesions in the mandibular body in a three-dimensional (3D) finite element model.

METHODS

A 3D finite element model of cystic lesion of the mandibular body was constructed based on the CT images of the mandible of a healthy adult female volunteer with normal occlusion. The size of the cyst and the residual bone wall were analyzed when the lesion area approached the stress peak under certain constraints and loading conditions.

RESULTS

When the size of the cyst reached 37.63 mm×11.32 mm×21.45 mm, the maximal von Mises stress in the lesion area reached 77.295 MPa, close to the yield strength of the mandible with a risk of pathological fracture. At this point, the remaining bone thickness of the buccal and lingual sides and the lower margin of the mandible in the lesion area was 1.52 mm, 0.76 mm and 1.04 mm, respectively.

CONCLUSIONS

Residual bone mass is an important factor to affect the risk of pathological fracture after curettage of cystic lesions. A thickness as low as 1 mm of the residual bone cortex in the cystic lesion area of the mandibular body can be used as the threshold for a clinical decision on one-stage windowing decompression combined with two- stage curettage.