Applying four anterior implants placed vertically or tilted in the mandible is considered to provide clinically reasonable results in the treatment of mandibular posterior edentulism. It is also reported that a combination of four anterior and two short posterior implants can be an alternative approach for the rehabilitation of severe atrophy cases. In this study, we aimed to evaluate the biomechanical responses of three different implant placement configurations, which represent the clinical options for the treatment of mandibular edentulism. Three-dimensional models of the mandible, prosthetic bar, dental implant, abutment, and screw were created. Finite element models of the three implant configurations (Protocol 1: Four anterior implants, Protocol 2: Four anterior and two short posterior implants, Protocol 3: Two anterior and two tilted posterior implants: All-on-4™ concept) were generated for 10 patients and analyzed under different loading conditions including chewing, biting, and impact forces. Protocol 2 led to the lowest stress concentrations over the mandible among the three protocols (p < 0.016). Protocol 2 resulted in significantly lower stresses than Protocol 3 and Protocol 1 over prosthetic bars under chewing forces (p < 0.016). None of the implant placement protocols consistently exhibited the lowest stress distribution over abutments. The lowest stresses over dental implants under the chewing, biting, and impact forces were obtained in Protocol 1, Protocol 2, and Protocol 3, respectively (p < 0.016). Protocol 3 was the best option to obtain the lowest stress values over the screws under all types of loading conditions (p < 0.016). In conclusion, Protocol 2 was biomechanically more ideal than Protocol 1 and Protocol 3 to manage the posterior edentulism.

在下颌骨中应用垂直或倾斜放置的四个前牙种植体被认为可以在治疗下颌后牙缺失时提供临床上合理的结果。据报道，四个前牙种植体和两个短后牙种植体的组合可以成为严重萎缩病例康复的替代方法。在本研究中，我们旨在评估三种不同种植体放置配置的生物力学响应，这些配置代表了治疗下颌牙缺失症的临床选择。创建了下颌骨、假肢杆、牙种植体、基台和螺钉的 3D 模型。三种种植体配置的有限元模型（协议 1：四个前牙种植体，协议 2：四个前牙和两个短后牙种植体，协议 3：为 10 名患者生成了两个前牙种植体和两个倾斜后牙种植体：All-on-4™ 概念，并在咀嚼、咬合和冲击力等不同负载条件下进行了分析。方案 2 导致三个方案中下颌骨的应力集中最低（p < 0.016)。在咀嚼力作用下，方案 2 比方案 3 和方案 1 对假肢棒产生显着更低的压力 ( p < 0.016)。没有一个种植体植入方案始终表现出基台上的最低应力分布。在咀嚼、咬合和冲击力下，牙种植体的最低应力分别在方案 1、方案 2 和方案 3 中获得 ( p < 0.016)。方案 3 是在所有类型的负载条件下获得最低螺钉应力值的最佳选择 ( p < 0.016)。总之，方案 2 在生物力学上比方案 1 和方案 3 更适合治疗后牙缺失。