Peak von Mises stress in micro-implants (MPa).

Asymmetric dentoskeletal expansion is one of the common complications associated with rapid palatal expansion (RPE), often leading to functional and aesthetic concerns. This study investigates the biomechanical performance of ATOZ™ expander using finite element method, with a focus on addressing asymmetrical expansion through expander design modifications. A 3D skull model incorporating teeth and sutures were reconstructed, and two scenarios were analyzed. Model I featured symmetrical suture maturation (stage B), and Model II with asymmetrical suture maturation, particularly more mature zygomatic sutures on the right side (Stage C). Five expander configurations were evaluated in each model. A 0.3 mm total displacement (0.15 mm per side) was applied parallel to the midpalatal suture. Results showed that in Model I, configurations 1, 2, and 3 resulted in relatively symmetrical expansion, while configurations 4 and 5 introduced asymmetry. In Model II, all configurations except configuration 4 demonstrated significant asymmetrical expansion toward the less mature left side. Configuration 4, which included one-sided dental support on the left, was found to redistribute forces and minimize asymmetry. The number of micro-implants had minimal impact on expansion outcomes, while dental support substantially influenced force distribution. These findings suggest that the ATOZ™ expander, especially when configured with one-sided dental support, offers a non-surgical solution to compensate for asymmetrical sutural resistance. This approach may improve clinical outcomes in patients exhibiting unilateral suture maturity and could help reduce the need for surgical intervention such as SARPE.

不对称牙颌面扩展是快速腭扩展（rapid palatal expansion, RPE）常见并发症之一，常引发功能与美观方面的问题。本研究采用有限元法探究ATOZ™扩弓器的生物力学性能，重点通过调整扩弓器设计来解决不对称扩展问题。研究重建了包含牙齿与骨缝的三维颅骨模型，并分析了两种场景：模型I模拟对称骨缝成熟状态（B期），模型II则为不对称骨缝成熟状态，其中右侧颧缝成熟度更高（C期）。两种模型均分别评估了5种扩弓器配置方案。沿腭中缝方向施加总位移为0.3mm（单侧0.15mm）的载荷。结果显示，在模型I中，配置1、2、3可实现相对对称的扩展，而配置4、5则会引发不对称扩展。在模型II中，除配置4外，其余所有配置均会导致扩展向成熟度更低的左侧发生显著偏移。其中配置4采用左侧单侧牙支持结构，可实现力的重新分布，将不对称程度降至最低。微种植体数量对扩展效果的影响极小，而牙支持结构则对力的分布影响显著。本研究结果表明，ATOZ™扩弓器（尤其是采用单侧牙支持配置时）可提供非手术方案，用以代偿不对称的骨缝阻力。该方案可改善单侧骨缝成熟患者的临床治疗效果，同时有助于降低手术辅助快速腭扩展（surgical assisted rapid palatal expansion, SARPE）等手术干预的需求。