Zhang Rongxiu, Zhang Lin, Wang Zeyu, Wu Zhigang
Rongxiu Zhang Department of Stomatology, The First Affiliated Hospital of Bengbu Medical University, Bengbu, Anhui,233004, P.R. China.
Lin Zhang Department of Stomatology, The First Affiliated Hospital of Bengbu Medical University, Bengbu, Anhui,233004, P.R. China.
Pak J Med Sci. 2025 Aug;41(8):2279-2284. doi: 10.12669/pjms.41.8.11943.
This study investigates the influence of varying periodontal ligament (PDL) heights on maxillary molar distalization using clear aligners (CAs). The analysis emphasizes the biomechanical impacts of PDL height reduction on stress distribution, tooth displacement, and anchorage control across two distalization modes: sequential and simultaneous.
This study is a retrospective single-case finite element analysis conducted at the First Affiliated Hospital of Bengbu Medical College. Data was obtained from a 26 years old male patient with Angle Class II malocclusion who presented at the hospital on March 19, 2024. Data collection was completed on the same day, and finite element modeling and biomechanical analysis were performed from March 20, 2024 to December 29, 2024. A finite element (FE) model was developed to evaluate molar movement in both sequential mode (where the second molar moved 3.00 mm prior to the first molar's 0.25 mm movement) and simultaneous mode (where both molars moved 0.25 mm concurrently). Simulations were conducted under three PDL conditions: full height (1.0-control group), moderate reduction (0.67), and severe reduction (0.33). Key biomechanical responses, including stress distribution within the PDL and initial displacement of molars and anterior teeth along three axes (X, Y, Z), were analyzed.
Reduced PDL height significantly amplified stress concentration near the cervical margin of molars and anterior teeth, with uneven stress patterns becoming pronounced under severe PDL reduction (0.33). This led to increased molar tipping and heightened anterior anchorage loss in both modes. Although sequential distalization minimized these adverse effects due to more controlled stress distribution, reduced PDL height remained a critical factor driving greater inefficiency and mechanical instability.
PDL height variations fundamentally influence molar distalization mechanics and anchorage stability, overshadowing the effects of distalization modes. Reduced PDL height intensifies stress imbalances and risks periodontal damage, underscoring the importance of personalized force management strategies in patients with compromised periodontal conditions.
本研究调查不同牙周膜（PDL）高度对使用透明矫治器（CA）进行上颌磨牙远移的影响。该分析强调了在两种远移模式（顺序式和同步式）下，PDL高度降低对应力分布、牙齿移动和支抗控制的生物力学影响。
本研究是在蚌埠医学院第一附属医院进行的一项回顾性单病例有限元分析。数据来自一名26岁的安氏II类错牙合男性患者，该患者于2024年3月19日就诊于该院。数据收集于同一天完成，有限元建模和生物力学分析于2024年3月20日至2024年12月29日进行。开发了一个有限元（FE）模型，以评估顺序模式（第二磨牙先移动3.00 mm，然后第一磨牙移动0.25 mm）和同步模式（两颗磨牙同时移动0.25 mm）下的磨牙移动情况。在三种PDL条件下进行模拟：全高度（1.0-对照组）、中度降低（0.67）和重度降低（0.33）。分析了关键的生物力学反应，包括PDL内的应力分布以及磨牙和前牙沿三个轴（X、Y、Z）的初始位移。
PDL高度降低显著放大了磨牙和前牙颈部边缘附近的应力集中，在严重PDL降低（0.33）时，应力分布不均匀变得更加明显。这导致两种模式下磨牙倾斜增加和前牙支抗丧失加剧。尽管顺序远移由于应力分布更可控而将这些不利影响降至最低，但PDL高度降低仍然是导致效率降低和机械不稳定加剧的关键因素。
PDL高度变化从根本上影响磨牙远移动力学和支抗稳定性，超过了远移模式的影响。PDL高度降低加剧了应力失衡并增加了牙周损伤的风险，凸显了在牙周状况受损的患者中采用个性化力管理策略的重要性。
