Biomedical Engineering Department, Faculty of Engineering, Helwan University, Cairo, Egypt.
BMC Oral Health. 2024 Aug 15;24(1):946. doi: 10.1186/s12903-024-04681-0.
Restorative treatment options for edentulous patients range from traditional dentures to fixed restorations. The proper selection of materials greatly influences the longevity and stability of fixed restorations. Most prosthetic parts are frequently fabricated from titanium. Ceramics (e.g. zirconia) and polymers (e.g. PEEK and BIOHPP) have recently been included in these fabrications. The mandibular movement produces complex patterns of stress and strain. Mandibular fractures may result from these stresses and strains exceeding the critical limits because of the impact force from falls or accidents. Therefore, it is necessary to evaluate the biomechanical behavior of the edentulous mandible with different restorations under different loading situations.
This study analyzes the biomechanical behavior of mandibles after four prosthetic restorations for rehabilitation under normal and impact loading scenarios.
The mandibular model was constructed with a fixed restoration, which was simulated using various materials (e.g. Titanium, Zirconia & BIOHPP), under frontal bite force, maximum intercuspation, and chin impact force. From the extraction of tensile and compressive stresses and strains, as well as the total deformation of mandible segments, the biomechanical behavior and clinical situations were studied.
Under frontal bite, the anterior body exhibited the highest tensile (60.34 MPa) and compressive (108.81 MPa) stresses using restoration 4, while the condyles and angles had the lowest tensile (7.12 MPa) and compressive (12.67 MPa) stresses using restoration 3. Under maximum intercuspation, the highest tensile (40.02 MPa) and compressive (98.87 MPa) stresses were generated on the anterior body of the cortical bone using restoration 4. Additionally, the lowest tensile (7.7 MPa) and compressive (10.08 MPa) stresses were generated on the condyles and angles, respectively, using restoration 3. Under chin impact, the highest tensile (374.57 MPa) and compressive (387.3 MPa) stresses were generated on the anterior body using restoration 4. Additionally, the lowest tensile (0.65 MPa) and compressive (0.57 MPa) stresses were generated on the coronoid processes using restoration 3. For all loading scenarios, the anterior body of the mandible had the highest stress and strain values compared with the other segments. Compared to the traditional titanium restoration.2, restoration.1(zirconia) increases the tensile and compressive stresses and strains on the mandibular segments, in contrast to restoration.3 (BIOHPP). In addition, zirconia implants exhibited higher displacements than the other implants.
In the normal loading scenario, the tensile and compressive stresses and strains on the mandible were within the allowable limits when all restorations were used. Under the chin impact loading scenario, the anterior body of the mandible was damaged by restorations 1 and 4.
无牙颌患者的修复治疗选择范围从传统义齿到固定修复体。材料的正确选择对固定修复体的寿命和稳定性有很大的影响。大多数修复体部件通常由钛制成。陶瓷（如氧化锆）和聚合物（如 PEEK 和 BIOHPP）最近也被用于这些制造中。下颌运动产生复杂的应力和应变模式。下颌骨折可能是由于下颌的这些应力和应变超过了临界极限，因为跌倒或事故产生的冲击力。因此，有必要在不同的加载情况下评估不同修复体的无牙颌的生物力学行为。
本研究分析了四种修复体在正常和冲击载荷下对下颌骨进行修复后的生物力学行为。
使用各种材料（如钛、氧化锆和 BIOHPP）模拟下颌模型的固定修复体，在额状咬合力、最大牙尖交错位和颏部撞击力下进行模拟。从拉伸和压缩应力和应变的提取，以及下颌骨段的总变形，研究生物力学行为和临床情况。
在额状咬合力下，第 4 种修复体的前体产生的拉伸（60.34 MPa）和压缩（108.81 MPa）应力最高，而第 3 种修复体的髁突和角产生的拉伸（7.12 MPa）和压缩（12.67 MPa）应力最低。在最大牙尖交错位时，第 4 种修复体的皮质骨前体产生的拉伸（40.02 MPa）和压缩（98.87 MPa）应力最高。此外，第 3 种修复体的髁突和角产生的拉伸（7.7 MPa）和压缩（10.08 MPa）应力最低。在颏部撞击力下，第 4 种修复体的前体产生的拉伸（374.57 MPa）和压缩（387.3 MPa）应力最高。此外，第 3 种修复体的喙突产生的拉伸（0.65 MPa）和压缩（0.57 MPa）应力最低。在所有加载情况下，下颌骨的前体与其他部位相比，具有最高的应力和应变值。与传统的钛修复体相比，修复体 1（氧化锆）增加了下颌骨各节段的拉伸和压缩应力和应变，而修复体 3（BIOHPP）则相反。此外，氧化锆种植体的位移比其他种植体高。
在正常加载情况下，使用所有修复体时，下颌骨的拉伸和压缩应力和应变都在允许范围内。在颏部撞击力下，下颌骨的前体受到修复体 1 和 4 的损伤。
