Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlândia, Uberlândia, Brazil.
Department of Periodontology and Implantology, Dental School, Federal University of Uberlândia, Uberlândia, Brazil.
Dent Traumatol. 2022 Dec;38(6):495-504. doi: 10.1111/edt.12777. Epub 2022 Jul 31.
BACKGROUND/AIMS: Dental traumatic injuries are common in children during the mixed dentition stage. These injuries usually require splinting for stabilization, which is complicated by the various stages of the permanent tooth development and primary tooth exfoliation. The aim of this study was to evaluate the effect on mobility of splint materials and extensions for an avulsed central incisor, stabilized with and without the adjacent incisor under intrusive and extrusive loading with different periodontal ligament (PDL) conditions.
Seventeen 3D model variations were created from a CBCT scan of a 7-year-old patient without erupted permanent upper lateral incisors. A 1000 N palatal load on the right central incisor simulated the avulsion injury and created an increased alveolus and bone deformation, resulting in an increased PDL thickness of 0.45 mm. Wire-resin composite splints with 0.9 mm cross-section (WCS) or 1.0 mm diameter nylon-resin composite splints (NCS) were created. The models simulated conditions with and without the adjacent upper central incisor. Two PDL conditions were investigated, simulating detached PDL or PDL with polyether impression material-like properties. Mobility was calculated under simulated biting loads in horizontal and vertical (intrusive and extrusive) directions.
The NCS allowed greater tooth mobility of the avulsed incisor than the WCS, irrespective of splint extension, PDL condition, or load application. During horizontal loading, polyether-like properties for the PDL allowed around 0.2 mm mobility of the avulsed tooth with the WCS, similar to the intact tooth, whereas a simulated detached PDL allowed 25% more mobility with a WCS than with a NCS.
Based on the FEA analysis, a 1.0 mm NCS may be suitable for splinting avulsion injuries during the mixed dentition stage compared to the considerably more rigid WCS. The NCS models provided flexibility for PDL healing while maintaining stability, even when missing adjacent teeth increased span widths. Extensions beyond directly adjacent teeth did not alter the mobility with the NCS but should still be considered an extra protection in case of bond failure or exfoliation.
背景/目的：儿童混合牙列期常见牙外伤。这些损伤通常需要夹板固定，这在恒压发育和乳压脱落的各个阶段都很复杂。本研究旨在评估不同牙周膜（PDL）条件下，带或不带邻牙的脱位中切牙在牙槽突增加和骨变形的情况下，用夹板材料和延长体固定后，对其动度的影响。
从一名 7 岁未萌出恒侧上中切牙的 CBCT 扫描中创建了 17 个 3D 模型变体。右侧中切牙施加 1000N 的腭向力模拟脱位损伤，导致牙槽突增加和骨变形，PDL 厚度增加 0.45mm。用 0.9mm 横截面的金属丝-树脂复合夹板（WCS）或 1.0mm 直径的尼龙-树脂复合夹板（NCS）制作夹板。模型模拟了有或没有邻牙的情况。研究了两种 PDL 条件，模拟分离的 PDL 或具有聚醚印模材料样性质的 PDL。在模拟的咬合载荷下，计算了水平和垂直方向（内向和外向）的动度。
NCS 允许脱位中切牙的动度大于 WCS，无论夹板延长、PDL 状况或载荷应用如何。在水平加载下，WCS 中 PDL 具有类似聚醚的性质时，允许脱位牙有大约 0.2mm 的动度，类似于完整的牙齿，而模拟分离的 PDL 时，WCS 的动度比 NCS 多 25%。
根据有限元分析，与相当刚性的 WCS 相比，1.0mm 的 NCS 可能更适合混合牙列期的牙脱位夹板固定。NCS 模型在保持稳定性的同时为 PDL 愈合提供了灵活性，即使缺失邻牙增加了跨度宽度。超出直接邻牙的延长体不会改变 NCS 的动度，但在粘结失败或脱落的情况下，仍应被视为额外的保护。
