Davide Apicella, Raffaella Aversa, Marco Tatullo, Michele Simeone, Syed Jamaluddin, Massimo Marrelli, Marco Ferrari, Antonio Apicella
Calabrodental Clinic, Tecnologica Research Institute, Crotone, Italy.
Advanced Materials Lab, Department of Architecture and Industrial Design, Second University of Naples, Naples, Italy.
Dent Mater. 2015 Dec;31(12):e289-305. doi: 10.1016/j.dental.2015.09.016. Epub 2015 Oct 28.
To quantify the influence of fracture geometry and restorative materials rigidity on the stress intensity and distribution of restored fractured central maxillary incisors (CMI) with particular investigation of the adhesive interfaces. Ancillary objectives are to present an innovative technology to measure the in vivo strain state of sound maxillary incisors and to present the collected data.
A validation experimental biomechanics approach has been associated to finite element analysis. FEA models consisted of CMI, periodontal ligament and the corresponding alveolar bone process. Three models were created representing different orientation of the fracture planes. Three different angulations of the fracture plane in buccal-palatal direction were modeled: the fracture plane perpendicular to the long axis in the buccal-palatal direction (0°); the fracture plane inclined bucco-palatally in apical-coronal direction (-30°); the fracture plane inclined palatal-buccally in apical-coronal direction (+30°). First set of computing runs was performed for in vivo FE-model validation purposes. In the second part, a 50N force was applied on the buccal aspect of the CMI models. Ten patients were selected and subjected to the strain measurement of CMI under controlled loading conditions.
The main differences were noticed in the middle and incisal thirds of incisors crowns, due to the presence of the incisal portion restoration. The stress intensity in -30° models is increased in the enamel structure close to the restoration, due to a thinning of the remaining natural tissues. The rigidity of the restoring material slightly reduces such phenomenon. -30° model exhibits the higher interfacial stress in the adhesive layer with respect to +30° and 0° models. The lower stress intensity was noticed in the 0° models, restoration material rigidity did not influenced the interfacial stress state in 0° models. On the contrary, material rigidity influenced the interfacial stress state in +30° and -30° models, higher rigidity restoring materials exhibits lower interfacial stress with respect to low rigidity materials.
Fracture planes inclined palatal-buccally in apical-coronal direction (+30°) reduce the interfacial stress intensity and natural tissues stress intensity with respect to the other tested configurations.
量化骨折几何形状和修复材料刚度对上颌中切牙（CMI）骨折修复后的应力强度及分布的影响，尤其对粘结界面进行研究。辅助目标是展示一种测量健康上颌中切牙体内应变状态的创新技术，并呈现所收集的数据。
已将验证性实验生物力学方法与有限元分析相结合。有限元分析模型包括上颌中切牙、牙周韧带及相应的牙槽骨。创建了三个模型，分别代表不同的骨折平面方向。模拟了颊腭方向骨折平面的三种不同角度：骨折平面在颊腭方向垂直于长轴（0°）；骨折平面在根尖 - 冠方方向颊腭向倾斜（-30°）；骨折平面在根尖 - 冠方方向腭颊向倾斜（+30°）。第一组计算运行是为了进行体内有限元模型验证。在第二部分中，对CMI模型的颊侧施加50N的力。选择了10名患者，并在受控加载条件下对其CMI进行应变测量。
由于切端部分修复的存在，在上颌中切牙牙冠的中部和切端三分之一处发现了主要差异。在-30°模型中，靠近修复体的牙釉质结构中的应力强度增加，这是由于剩余天然组织变薄所致。修复材料的刚度略微减轻了这种现象。与+30°和0°模型相比，-30°模型在粘结层中表现出更高的界面应力。在0°模型中观察到较低的应力强度，修复材料刚度对0°模型中的界面应力状态没有影响。相反，材料刚度影响了+30°和-30°模型中的界面应力状态，相对于低刚度材料，高刚度修复材料表现出较低的界面应力。
相对于其他测试构型，在根尖 - 冠方方向腭颊向倾斜（+30°）的骨折平面降低了界面应力强度和天然组织应力强度。
