Parameter optimization in a finite element mandibular fracture fixation model using the design of experiments approach

Simulation of a Custom-Made Temporomandibular Joint-An Academic View on an Industrial Workflow

Temporomandibular joint replacement is a critical intervention for severe temporomandibular joint disorders, enhancing pain levels, jaw function and overall quality of life. In this study, we compare two finite element method-based simulation workflows from both academic and industrial perspectives, focusing on a patient-specific case involving a custom-made temporomandibular joint prosthesis. Using computed tomography data and computer-aided design data, we generated different 3D models and performed mechanical testing, including wear and static compression tests. Our results indicate that the academic workflow, which is retrospective, purely image-based and applied post-operatively, produced peak stress values within 9-20% of those obtained from the industrial workflow. The industrial workflow is prospective, pre-operative, computer-aided design-based and guided by stringent regulatory standards and approval protocols. Observed differences between workflows were attributed primarily to distinct modelling assumptions, simplifications and constraints inherent in each method. To explicitly quantify these differences, multiple additional models were generated within the academic workflow using partial data from the industrial process, revealing specific sources of variation in stress distribution and implant performance. The findings underscore the potential of patient-specific simulations not only to refine temporomandibular joint prosthesis design and enhance patient outcomes, but also to highlight the interplay between academic research methodologies and industrial standards in the development of medical devices.

Finite element analysis of mandibular fracture fixation authenticated by 3D printed mandible mechanical testing

Finite element analysis (FEA) for mandibular fracture fixation in craniomaxillofacial surgery remains promising but has been restricted due to the absence of an authenticated FEA model. This study aims to create an authenticated FEA model. This model was verified through a series of 3D printed mandible mechanical testing (3D-MMT) in a universal tensile machine using an indistinguishable set-up. Non-comminuted mandibular symphysis, parasymphysis, and angle fracture fixation stability were evaluated using a 2.0 mm 4-hole miniplate in three different plate configurations. Both FEA and 3D-MMT outcomes were reproducible and in agreement with the present understanding of stable mandibular fracture treatment. The results show favourable fracture stability with the dual plating, followed by the superior border, with the least stability observed in the inferior border plating. Furthermore, the FEA and the 3D-MMT outcomes were consistently similar, with a systematic 0.56 ± 0.12 mm total displacement difference (standard deviation). An excellent interclass relation coefficient (0.93, 95% confidence interval: 0.80-0.96) was found between the FEA model and the 3D-MMT mechanical test, indicating that both results were consistent with each other. The authenticated FEA can accurately study the recognised biomechanical behaviour of non-comminuted mandibular fractures and shows a potential application for complex fracture fixation analysis.

Comparison between 2- and 4-plate fixation in Le Fort I osteotomy: a mixed methods systematic review

OBJECTIVE

Achieving postsurgical skeletal stability is crucial for successful outcomes and patient satisfaction. Precision maxillofacial surgery, which integrates precision techniques with minimally invasive approaches, is increasingly recognized for its potential to enhance long-term stability and reduce surgical risks and complications. This study aimed to comprehensively evaluate the impact of fixation techniques (2 vs 4 plates) during Le Fort I osteotomy in orthognathic surgery on skeletal stability. The main focus was to compare the stability achieved and potential risks of relapse between these two fixation methods.

MATERIAL AND METHODS

A mixed-methods approach was employed, combining a systematic review, in silico analysis, and in vitro studies. The systematic review adhered to Joanna Briggs Institute methodology and Good Reporting of A Mixed Methods Study guidelines, focusing on comparative studies that evaluated skeletal stability as the primary outcome measure. In silico and in vitro analyses were conducted to assess the biomechanical principles and relapse risks associated with maxillary advancement using different fixation techniques.

RESULTS

The systematic review included three clinical trials, four finite element analysis studies, and two in vitro analyses. The meta-analysis revealed no significant difference in skeletal stability between the 2- and 4-plate fixation methods. However, biomechanical analysis showed an atypical increase in relapse risk with 2-plate fixation at 3 mm maxillary advancement, compared to a 10 mm advancement for 4-plate fixation.

CONCLUSIONS

While both 2- and 4-plate fixation methods are viable, the findings suggest that 4-plate fixation offers superior stability, particularly in cases of significant maxillary advancement, where 2-plate fixation showed an increased risk of relapse. Future research with larger sample sizes and addressing the biases identified in this study is needed to validate these findings and effectively guide clinical practice.

Biomechanical assessment of mandibular fracture fixation using finite element analysis validated by polymeric mandible mechanical testing

The clinical finite element analysis (FEA) application in maxillofacial surgery for mandibular fracture is limited due to the lack of a validated FEA model. Therefore, this study aims to develop a validated FEA model for mandibular fracture treatment, by assessing non-comminuted mandibular fracture fixation. FEA models were created for mandibles with single simple symphysis, parasymphysis, and angle fractures; fixated with 2.0 mm 4-hole titanium miniplates located at three different configurations with clinically known differences in stability, namely: superior border, inferior border, and two plate combinations. The FEA models were validated with series of Synbone polymeric mandible mechanical testing (PMMT) using a mechanical test bench with an identical test set-up. The first outcome was that the current understanding of stable simple mandibular fracture fixation was reproducible in both the FEA and PMMT. Optimal fracture stability was achieved with the two plate combination, followed by superior border, and then inferior border plating. Second, the FEA and the PMMT findings were consistent and comparable (a total displacement difference of 1.13 mm). In conclusion, the FEA and the PMMT outcomes were similar, and hence suitable for simple mandibular fracture treatment analyses. The FEA model can possibly be applied for non-routine complex mandibular fracture management.

The butterfly effect in oral and maxillofacial surgery: Understanding and applying chaos theory and complex systems principles

The present paper provides a historical context for chaos theory, originating in the 1960s with Edward Norton Lorenz's efforts to predict weather patterns. It introduces chaos theory, fractal geometry, nonlinear dynamics, and the butterfly effect, highlighting their exploration of complex systems. The authors aim to bridge the gap between chaos theory and oral and maxillofacial surgery (OMFS) through a literature review, exploring its applications and emphasizing the prevention of minor deviations in OMFS to avoid significant consequences. A comprehensive literature review was conducted on PubMed, Web of Science, and Google Scholar databases. The selection process adhered to the PRISMA-ScR guidelines and Leiden Manifesto principles. Articles focusing on chaos theory principles in health sciences, published in the last two decades, were included. The review encompassed 37 articles after screening 386 works. It revealed applications in outcome variation, surgical planning, simulations, decision-making, and emerging technologies. Potential applications include predicting infections, malignancies, dental fractures, and improving decision-making through disease prediction systems. Emerging technologies, despite criticisms, indicate advancements in AI integration, contributing to enhanced diagnostic accuracy and personalized treatment strategies. Chaos theory, a distinct scientific framework, holds potential to revolutionize OMFS. Its integration with advanced techniques promises personalized, less traumatic surgeries and improved patient care. The interdisciplinary synergy of chaos theory and emerging technologies presents a future in which OMFS practices become more efficient, less traumatic, and achieve a level of precision never seen before.