Biomechanical interactions of different mini-plate fixations and maxilla advancements in the Le Fort I Osteotomy: a finite element analysis

Abstract

This study investigates the biomechanical interaction of different mini-plate fixation types (shapes/sizes and patterns) with segmental advancement levels on the Le Fort I osteotomy using the non-linear finite element (FE) approach. Nine models were generated under a standard 1-piece LeFort I osteotomy for advancement with 3, 6 and 9 mm distances and four mini-plates with three fixation patterns including LL, LI, and II patterns placed on the maxillae models by integrating computed tomography images and computer-aided design system. The axial and oblique occlusal forces were 250 N applied to each premolar/molar and 125 N applied at 30° inclination to the tooth long axis and from palatal to buccal, respectively. The relative micro-movement values between the two maxillary bone segments and maximum mini-plate stress increased obviously with maxilla advancement increment and the increasing trend can be fitted by exponential curve. The corresponding values in II mini-plate fixation presented apparently high values in all simulated cases. The mini-plate stress concentration locations were found at the bending regions to increase high fracture risk. The mini-plate yield strength can be mapped to a critical (limited) advancement for three types of fixations for safe consideration. This study concluded that L-shaped mini-plates with lateral fixation are recommended to provide better stability. The risk for mini-plate fracture and bone relapse increases when maxillary advancement is larger than a critical value of 5 mm in the Le Fort I osteotomy.

Efficacy and morbidity of biodegradable versus titanium osteosyntheses in orthognathic surgery: A systematic review with meta‐analysis and trial sequential analysis

“…Therefore, future research should have at least a 1-year follow-up and should distinguish osteosyntheses with plates and screws vs. only screws to assess the symptomatic device removal rate appropriately. The mandible is exposed to considerably higher biomechanical forces compared to the maxilla [70,71]. Higher forces acting on the mandible may lead to loosening of screws and, thereafter, to inflammation especially in osteotomies because, unlike fractures, there is no interfragmentary stability [2].…”

“…The mandible is exposed to considerably higher biomechanical forces compared to the maxilla [ 70 , 71 ]. Higher forces acting on the mandible may lead to loosening of screws and, thereafter, to inflammation especially in osteotomies because, unlike fractures, there is no interfragmentary stability [ 2 ].…”

Titanium or Biodegradable Osteosynthesis in Maxillofacial Surgery? In Vitro and In Vivo Performances

“…The masticatory forces after mandibular reconstructions ranged from 28 to 186 N [ 166 ]. However, the mechanical stress surrounding osteosynthesis systems is multi-factorial and is affected by the location of the fracture [ 1 ], differences in interfragmentary stability [ 1 ], mandibular height [ 1 ], degree and direction of movement [ 167 ], and preoperative masticatory forces [ 159 , 168 , 169 ]. Load-sharing osteosynthesis allows sharing of the load between bone segments and the osteosynthesis system (e.g., fractures with interfragmentary stability) whereas in load-bearing osteosynthesis, the complete load at the fracture site is carried by the osteosynthesis system without interfragmentary stability [ 1 , 170 ].…”

Biomechanical evaluation of Chinese customized three-dimensional printed titanium miniplate in the Lefort I osteotomy: A finite element analysis

“…Huang et al found that L-shaped mini-plates with lateral fixation provide better stability. However, the risk for mini-plate fracture increases when maxillary advancement is larger than 5 mm [ 9 ]. As the traditional titanium mini-plates demand contouring to fit maxillary geometry profiles for each individual patient, it may affect the accuracy of placement [ 10 ].…”