Biomechanical analysis of skeletal open bite treatment methods: a comparative finite element study

The biomechanical effects of zygomatic anchorage plates, vertical chin-caps, and occipital headgear on dentofacial structures in patients with skeletal anterior open bite malocclusion were compared using three-dimensional finite element analysis.

Three-dimensional finite element models were constructed based on computed tomography data obtained from a patient with skeletal anterior open bite. Simulation models representing zygomatic anchorage-supported intrusion, vertical chin-cap, and occipital headgear were generated under fixed orthodontic conditions. In each scenario, a unilateral force of 200 g (1.96 N) was applied along clinically relevant force vectors. Stress distributions in craniofacial bones, sutural structures, teeth, roots, and temporomandibular joint components, as well as displacement patterns of the teeth and roots, were evaluated. Von Mises stress was used to assess craniofacial and dental structures, whereas minimum principal stress was used to evaluate sutural regions.

The highest von Mises stress within craniofacial structures was observed in the posterior maxilla in the zygomatic anchorage plate scenario, followed by the vertical chin-cap and occipital headgear scenarios. Across all models, compressive stresses in sutural structures were predominantly concentrated in the zygomaticomaxillary suture, with the greatest magnitude observed in the zygomatic anchorage model. Dental and root stress analyses revealed peak von Mises stress at the mesiobuccal root of the maxillary first molar, particularly in the zygomatic anchorage scenario. The greatest tooth and root displacements along the vertical axis, indicative of intrusion, were also observed in this model. Condylar stress was primarily localized in the superior region of the condyle, with higher peak values observed in the vertical chin-cap simulation.

Within the limitations of finite element analysis, zygomatic anchorage-supported intrusion demonstrated greater predicted posterior maxillary intrusion and higher localized stress concentrations than vertical chin-cap and occipital headgear approaches. These findings indicate distinct biomechanical profiles among the appliances, which should be considered when selecting treatment strategies for skeletal anterior open bite.