Two versus three magnesium screws for osteosynthesis of mandibular condylar head fractures: a finite element analysis.

Objectives: Previous finite element analyses (FEA) have shown promising results for using two titanium screws in treating mandibular condylar head fractures but limited mechanical stability of a two-screw osteosynthesis with magnesium screws. Given the potential benefits of magnesium screws in terms of biocompatibility and resorption, this study aimed to compare two- and three-screw osteosynthesis solutions for a right condylar head fracture (AO CMF type p) with magnesium screws with a FEA.

Materials and methods: A previously validated finite element model simulating a 350 N bite on the contralateral molars was used to analyze von Mises stress within the screws, fragment deformation, and fracture displacement. All screws were modeled with uniform geometric specifications mirroring the design of Medartis MODUS^® Mandible Hexadrive cortical screws.

Results: The three-screw configuration demonstrated lower values for all three parameters compared to the two-screw scenario. There was a 30% reduction in maximum von Mises stress for the top screw and a 46% reduction for the bottom screw.

Conclusions: Fracture treatment with three magnesium screws could be a valuable and sufficiently stable alternative to the established treatment with titanium screws. Further studies on screw geometry could help improve material stability under mechanical loading, enhancing the performance of magnesium screws in clinical applications.

Clinical relevance: The use of magnesium screws for osteosynthesis of mandibular condylar head fractures offers the benefit of reducing the need for second surgery for hardware removal. Clinical data is needed to determine whether the advantages of resorbable screw materials outweigh potential drawbacks in condylar head fracture treatment.