In this paper, we assess the pressure between the overdenture located in the mandible and supported by a bar retained on two implants and the prosthodontic area. For testing, a model of an edentulous mandible was created using a mold by FRASACO with two implants and a “rider” bar inserted. A complete mandibular denture with polypropylene matrices was made. Three types of matrices of various stiffness were applied. The mandible and overdenture geometry was mapped using a digital image obtained with a Steinbichler Comet L3D 3D scanner. Finite element method calculations were performed in the Abaqus FEA software. The results demonstrate that the maximum contact pressure is observed when the loads are associated with canines. A critical case for the lower posterior is chewing performed by the molars. The pressure zone is the largest for POM-1 with Young’s modulus of 1.5 GPa and is reduced by 5.0% and 7.8% for POM-2 (E = 2.5 GPa) and POM-3 (E = 3.5 GPa), respectively. The stress distribution under the prosthesis mostly depends on the region loaded onto it. The applied load produces a slight contact pressure between the denture and the prosthodontic area in the anterior zone. A change in polypropylene matrix stiffness does not affect contact pressures.

中文翻译：

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下颌覆盖义齿与修复区之间的接触压力评估

在本文中，我们评估了位于下颌骨中的覆盖义齿和由保留在两个植入物上的牙棒支撑的义齿与义齿区域之间的压力。为了进行测试，使用FRASACO的模具创建了一个无牙颌的模型，该模具带有两个植入物和一个插入的“鞍形”杆。制成具有聚丙烯基体的完整的下颌假牙。应用了三种类型的各种刚度的矩阵。使用通过Steinbichler Comet L3D 3D扫描仪获得的数字图像来绘制下颌和覆盖义齿的几何图形。有限元方法计算是在Abaqus FEA软件中进行的。结果表明，当负载与犬齿相关时，观察到最大接触压力。下后牙的关键情况是磨牙进行咀嚼。对于杨氏模量为1.5 GPa的POM-1，压力区最大，而对于POM-2（E = 2.5 GPa）和POM-3（E = 3.5 GPa），压力区分别减小了5.0％和7.8％。假体下的应力分布主要取决于负载在其上的区域。施加的载荷在义齿和前区的义齿区域之间产生轻微的接触压力。聚丙烯基质刚度的变化不会影响接触压力。