Abstract: BACKGROUND: Customized titanium plates are used to heal maxillofacial fractures, reducing surgical time and improving patient satisfaction. However, there is still a lack of systematic research on the optimal shape design of personalized titanium plates and their effects on fracture healing.
OBJECTIVE: To optimize the design of personalized titanium plates for median mandibular fractures using finite element analysis.
METHODS: The initial titanium plate and jaw model were imported into the software for static analysis, and topological optimization was performed based on the results of static analysis. The basic shape of the personalized titanium plate was designed based on the topological optimization results. Finite element analysis was performed on the personalized titanium plate, parallel double-plate titanium plate, and vertical double-plate titanium plate under three working conditions: bilateral incisor occlusion (working condition 1), right molar occlusion (working condition 2), and right incisor occlusion (working condition 3), respectively, to select the titanium plate with the best mechanical properties in the fixation of median mandibular fractures. According to the analysis results, the personalized titanium plate was further optimized and designed into three forms: straight, upward curved, and downward curved. The optimal form was selected through finite element analysis. Based on the 1 mm thick upward curved personalized titanium plate, the titanium plates with beams (cross beams and inclined beams) of 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mm width were designed. The appropriate beam width was determined by finite element analysis to complete the optimization design of the personalized titanium plate.
RESULTS AND CONCLUSION: (1) According to the topology optimization results, an “8” shaped individual titanium plate was designed. The finite element analysis showed that in working condition 1, the maximum equivalent stress of the titanium plate in the parallel double-plate titanium plate group was the smallest, and the maximum displacement of the bone end in the vertical double-plate titanium plate group was the smallest. In working conditions 2 and 3, the maximum equivalent stress of the titanium plate and the maximum displacement of the bone end in the personalized titanium plate group were the smallest, and the mechanical properties were better. (2) Under the three working conditions, the maximum equivalent stress of the titanium plate and the maximum displacement of the bone end of the linear personalized titanium plate group, the upward curved personalized titanium plate group, and the downward curved personalized titanium plate group were slightly different, but the stress distribution of the titanium plate in the upward curved personalized titanium plate group was more uniform. (3) For the 1 mm thick upward curved personalized titanium plate, when the beam width was ≥ 1.6 mm, the maximum equivalent stress of the titanium plate and the maximum displacement of the bone end were relatively stable. When the beam width was < 1 mm, the maximum displacement of the bone end exceeded the range of initial fracture healing, which was not conducive to healing. (4) In the finite element analysis of mandibular median fracture, the “8”-shaped personalized titanium plate has the advantages of more uniform stress distribution and more stable fixation than the plate shaped like a straight line (“—”). Finally, it is determined that the 1 mm beam width and 1 mm thick upward curved personalized titanium plate is the optimal design scheme for the personalized titanium plate of mandibular median fracture.

Key words: personalized, titanium plate, optimizing, chin, mandibular, fracture, fixation, finite element analysis