Finite element analysis of temporomandibular joint stress distribution during treatment with novel digital composite plates and invisible aligners.

Abstract

<h4>Background</h4>Skeletal Class II malocclusion is frequently occurred in patients with orthodontics. Improper treatment may lead to double occlusion, joint pain, snapping and other symptoms. This study aims to investigate the biomechanical effects of a novel digital composite invisible appliance in treating Class II malocclusion with flexible pre-disc displacement.<h4>Methods</h4>A 3D finite element model (FEM) of the temporomandibular joint (TMJ) was constructed and simulated for three treatment stages: pre-correction, mid-correction, and post-correction. Stress distribution and gap variations were quantified at each stage using dynamic mechanical simulations. Key biomechanical parameters, including stress on the condyles, joint discs, and joint sockets, were analyzed. Statistical tests were used to assess significant differences in stress values and their spatial distribution.<h4>Results</h4>The maximum stress on the articular disc in the closed-mouth state was 5.68 MPa in the pre-orthodontic phase, 4.16 MPa in the orthodontic phase, and 1.92 MPa in the post-orthodontic phase. The differences in stress across these phases were statistically significant (P < 0.001). In the open-mouth condition, the maximum stress values were 5.45 MPa during the pre-corrective and mid-corrective stages, decreasing to 3.55 MPa in the post-corrective stage. The stress differences between these stages were also statistically significant (P < 0.001). Regarding joint space measurements, before correction, the anterior, superior, and posterior gaps were 2.87 mm, 2.53 mm, and 1.53 mm, respectively. During correction, the anterior and posterior gaps measured 2.80 mm and 2.93 mm, respectively. After correction, the anterior, superior, and posterior gaps were 2.08 mm, 2.69 mm, and 2.26 mm, respectively, indicating a more uniform distribution of joint spaces.<h4>Conclusion</h4>The novel digital composite invisible appliance significantly improves the biomechanical environment of the TMJ. It reduces stress concentrations on the joint disc, promotes uniform stress distribution, and optimizes the joint's mechanical environment, thereby lowering the risk of joint injury during treatment.