State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, PR China.
BMC Oral Health. 2024 Sep 27;24(1):1128. doi: 10.1186/s12903-024-04890-7.
Failure to restore missing teeth in time can easily lead to the mesial tilting of the distal abutment teeth. However, a fixed partial denture (FPD) can improve stress conduction and distribution and prevent periodontal injuries. In these more complex cases, it is necessary to consider various factors comprehensively to improve conventional treatment planning and achieve better results.
We selected a patient with a missing first molar and a mesial inclination of the second molar, leaving inadequate space or bone mass for implant denture restoration, necessitating an FPD for restoration. Three-dimensional finite element analysis (3D-FEA) combined with photoelastic analysis were used to explore how the inclination angle (0 ‒ 30°) and different dental restoration materials (zirconia, lithium disilicate, polymer-infiltrated ceramic network, and resin composite) affect the biomechanical behaviour of FPD‒abutments‒periodontal tissue complex.
The stress was easily concentrated in the FPD connectors, enamel shoulder collar, periapical area, and root bifurcation. The stress on FPD and the periodontal ligament (PDL) of the second premolar increased with an increase in the elastic modulus of FPD, with an opposite trend in the abutments, the alveolar bone, and the PDL of the second molar. The stress on the FPD and alveolar bone increased with increased inclination angle of the distal abutment. The stress on two abutments and their PDL were positively correlated with the inclination angle in two stages; however, when the inclination angle > 12°, the second premolar and its PDL showed a negative correlation.
FPDs can be used for restoration within 24° of distal abutment inclination, but protecting the abutments (< 12° especially) and the periodontal tissue (> 12° especially) must be taken seriously. For this purpose, an FPD material with higher strength is recommended.
未能及时修复缺失的牙齿，容易导致邻牙向缺牙区倾斜。然而，固定局部义齿（FPD）可以改善应力传导和分布，防止牙周损伤。在这些更为复杂的情况下，需要综合考虑各种因素，以改进常规治疗计划并获得更好的效果。
我们选择了一位缺失第一磨牙且第二磨牙向近中倾斜的患者，缺牙区牙槽骨量或间隙不足，无法进行种植义齿修复，需要采用 FPD 修复。我们采用三维有限元分析（3D-FEA）结合光弹分析，研究了倾斜角度（0-30°）和不同牙体修复材料（氧化锆、锂硅二酸盐、聚合体渗透陶瓷网络和树脂复合材料）对 FPD-基牙-牙周组织复合体生物力学行为的影响。
FPD 连接体、牙釉质肩台、根尖区和根分叉处的应力容易集中。随着 FPD 弹性模量的增加，FPD 和第二前磨牙牙周膜（PDL）的受力增加，而基牙、牙槽骨和第二磨牙的 PDL 则相反。随着远中基牙倾斜角度的增加，FPD 的受力和牙槽骨的受力也随之增加。两个基牙及其 PDL 的受力与倾斜角度呈正相关，分两个阶段；然而，当倾斜角度>12°时，第二前磨牙及其 PDL 呈负相关。
在远中基牙倾斜 24°以内的情况下，可以使用 FPD 进行修复，但必须认真保护基牙（特别是<12°）和牙周组织（特别是>12°）。为此，建议使用强度更高的 FPD 材料。
