Evaluation of labial versus labio-inferior lines of osteosynthesis using 3D miniplate for fractures of anterior mandible: A finite element analysis with a pilot clinical trial

PURPOSE: The fractures of anterior mandible are subject to severe torsional forces due to muscles acting in opposite directions. 3D miniplate has been suggested as a good alternative by some researchers. However, finite element model (FEM) studies indicate that labio-inferior positioning of two miniplates perpendicular to each other offers better stability as compared to labial positioning. This study aims at combining the advantages of a single 3D miniplate and labio-inferior positioning of two conventional miniplates, which was assessed by finite element analysis along with a pilot clinical trial. METHODS: Two FEM models were created using CT data of a 24-year-old patient with Angle class I occlusion: control model with labial plating and study model with labio-inferior plating. The models were processed with MIMICS® (materialise, Leuven, Belgium), CATIA® (Dassault Systemes) and finite element analysis softwares. Parameters adopted for analysis were (1) displacement (mm) of fracture fragments during each screw fixation, (2) lingual splay and post fixation stability of fracture fragments with masticatory load, and (3) stress distribution (MPa) across fracture fragments. Moreover, a pilot clinical trial including five patients with anterior mandible fracture was conducted. The fractures were managed by intraoral open reduction and 3D miniplate fixation in labio-inferior position. Intraoperative interfragmentary gap, post fixation lingual splay and radiographic fracture union and complications were assessed clinically. RESULTS: Labio-inferior plating demonstrated less displacement (mm) of fracture fragments during screw fixation (0.059 vs. 0.079) as well as after application of masticatory load (1.805 vs. 1.860). Negligible lingual splay and less stress distribution (MPa) across fracture fragments (1.860 vs. 1.847) were appreciated in the study group as compared to control group. Clinical trial support the favorable outcome related to intraoperative and postoperative assessment parameters. CONCLUSION: FEM analysis and clinical trial reveal better results with labio-inferior positioning of 3D miniplate when compared to labial positioning.