Stability and dynamics of the fractured zygomaticomaxillary complex fixed using non-resorbable and resorbable 2- and 3-point miniplates, under physiological and maximal occlusal loads: a finite element analysis

Introduction: Given that zygoma fractures are the second most common facial trauma, knowledge of their treatments is of clinical value. Among these are fixations methods, which despite their importance are neglected in many aspects. Therefore, for the first time in the literature, the present finite element analysis evaluated displacements and dynamics of the zygoma fixed using four 2- and 3-point resorbable and four non-resorbable plates under normal and maximal mastication loads. Methods: A maxillofacial CT scan of a man with linear fractures without severe displacements was used to model the zygoma and its adjacent bones. Seven combinations of resorbable and seven combinations of non-resorbable mini-plates 2mm thick were fixed on the zygoma (orbital rim, zygomaticomaxillary buttress [ZMB], and frontozygomatic [FZ]) using 6mm miniscrews. ZMB was fixed using an L-shaped 4-hole plate. The infraorbital rim was fixed with a curved 5-hole miniplate. The FZ suture area was fixed with a 4-hole miniplate. The model underwent 150N and 750N loads. Minimum and maximum displacements, rotational displacements, stresses, and strains of the zygoma models were calculated. Results: Non-resorbable fixation methods can yield much smaller stresses, strains, and displacements compared to resorbable fixations. Also the parameters were much smaller under the 150N load compared to the 750N load. The worst results belonged to the fixation of Rim and ZMB and the best results belonged to the fixation of ZMB-Rim, and especially FZ-ZMB, Rim-FZ, and FZ-ZMB-Rim. Conclusions: In patients with heavy masticatory forces, it is not recommended to use resorbable plates.