Abstract：
BACKGROUND: With periodontal disease having an increasing incidence, mandibular free-end edentulism caused by periodontitis is clinically more common. Finite element analysis and clinical case reports were used to evaluate the influence of different designs on the load distribution of implant prosthesis in mandibular posterior free-end edentulism.
METHODS: A finite element model of a mandible with posterior free-end edentulism was established. Considering the implant position and selection of single crown repair or splint repair, four designs were conducted including model A: 3435 × 37(four-unit fixed bridge supported by three implants, implant positions were 34, 35, 37); model B: 34,35 × 37, (34: a single implant crown) (35 ×37: three-unit fixed bridge supported by two implants, implant positions were 35, 37); model C: 34 × 3637(four-unit fixed bridge supported by three implants, implant positions were 34, 36, 37); and model D: 34 × 36, 37(37: a single implant crown)(34 ×36: three-unit fixed bridge supported by two implants, implant positions were 34, 36). Stress distribution and the Von Mises stress value of the implants, the crown and the bone around the implants were analyzed at vertical and 45° inclined load.
RESULTS: Stress in the cortical bone was mainly concentrated around the implant neck, and maximum Von Mises stress (MVMS) of the four models was 11.6-16.1 MPa at vertical load and 61.74-96.49 MPa at 45° inclined load. Stress in the cancellous bone was concentrated around the implant base, and MVMS of four models was 3.075-3.899 MPa at vertical load and 5.021-6.165 MPa at 45° inclined load. Stress of the restoration crowns was mainly concentrated in the connector of the bridge, and MVMS of four models was 23.38-26.28 MPa at vertical load and 53.14-56.35 MPa at 45° inclined load. Stress of the implant interface was mainly concentrated on the surface of the smaller implants near the bridge, and MVMS of four models was 21.12-33.25 MPa at vertical load and 83.73-138.7 MPa at 45° inclined load.
CONCLUSIONS: There was favorable stress distribution of the four models at vertical load and 45° inclined load. Design of a three-unit fixed bridge combined with a partial crown may be an available option for devising patient treatment plans with mandibular free-end edentulism.
METHODS: A finite element model of a mandible with posterior free-end edentulism was established. Considering the implant position and selection of single crown repair or splint repair, four designs were conducted including model A: 3435 × 37(four-unit fixed bridge supported by three implants, implant positions were 34, 35, 37); model B: 34,35 × 37, (34: a single implant crown) (35 ×37: three-unit fixed bridge supported by two implants, implant positions were 35, 37); model C: 34 × 3637(four-unit fixed bridge supported by three implants, implant positions were 34, 36, 37); and model D: 34 × 36, 37(37: a single implant crown)(34 ×36: three-unit fixed bridge supported by two implants, implant positions were 34, 36). Stress distribution and the Von Mises stress value of the implants, the crown and the bone around the implants were analyzed at vertical and 45° inclined load.
RESULTS: Stress in the cortical bone was mainly concentrated around the implant neck, and maximum Von Mises stress (MVMS) of the four models was 11.6-16.1 MPa at vertical load and 61.74-96.49 MPa at 45° inclined load. Stress in the cancellous bone was concentrated around the implant base, and MVMS of four models was 3.075-3.899 MPa at vertical load and 5.021-6.165 MPa at 45° inclined load. Stress of the restoration crowns was mainly concentrated in the connector of the bridge, and MVMS of four models was 23.38-26.28 MPa at vertical load and 53.14-56.35 MPa at 45° inclined load. Stress of the implant interface was mainly concentrated on the surface of the smaller implants near the bridge, and MVMS of four models was 21.12-33.25 MPa at vertical load and 83.73-138.7 MPa at 45° inclined load.
CONCLUSIONS: There was favorable stress distribution of the four models at vertical load and 45° inclined load. Design of a three-unit fixed bridge combined with a partial crown may be an available option for devising patient treatment plans with mandibular free-end edentulism.
摘要：
背景：随着牙周病发病率的增加，牙周炎引起的下颌骨游离端水肿在临床上较为常见。通过有限元分析和临床病例报告，评估了不同设计对下颌后端自由端无牙种植假体载荷分布的影响。
方法：建立了下颌骨后端自由端无食性的有限元模型。考虑到种植位置和选择单冠修复或夹板修复，进行了四次设计，包括模型A：3435×37（由三个植入物支撑的四单元固定桥，植入物位置为34、35、37）；模型B：34,35×37，（34：单个植入物冠）（35×37：由两个植入物支撑的三单元固定桥，植入物位置为35，37）；模型C：34×3637（由三个植入物支撑的四单元固定桥，植入物位置为34、36、37）；模型D：34×36，37（37：单个植入物冠）（34×36：由两个植入物支撑的三单元固定桥，植入位置为34，36）。植入物的应力分布和VonMises应力值，在垂直和45°倾斜载荷下分析牙冠和植入物周围的骨骼。
结果：皮质骨中的应力主要集中在种植体颈部周围，四个模型的最大VonMises应力（MVMS）在垂直载荷下为11.6-16.1MPa，在45°倾斜载荷下为61.74-96.49MPa。松质骨中的应力集中在植入物基部周围，四个模型的MVMS在垂直载荷下为3.075-3.899MPa，在45°倾斜载荷下为5.021-6.165MPa。修复冠的应力主要集中在桥梁的连接件上，四个模型的MVMS在垂直载荷下为23.38-26.28MPa，在45°倾斜载荷下为53.14-56.35MPa。种植体界面的应力主要集中在桥附近较小的种植体表面,四个模型的MVMS在垂直载荷下为21.12-33.25MPa，在45°倾斜载荷下为83.73-138.7MPa。
结论：在垂直载荷和45°倾斜载荷下，四种模型的应力分布良好。结合部分牙冠的三单元固定桥的设计可能是设计下颌自由端无牙症患者治疗计划的可用选择。
方法：建立了下颌骨后端自由端无食性的有限元模型。考虑到种植位置和选择单冠修复或夹板修复，进行了四次设计，包括模型A：3435×37（由三个植入物支撑的四单元固定桥，植入物位置为34、35、37）；模型B：34,35×37，（34：单个植入物冠）（35×37：由两个植入物支撑的三单元固定桥，植入物位置为35，37）；模型C：34×3637（由三个植入物支撑的四单元固定桥，植入物位置为34、36、37）；模型D：34×36，37（37：单个植入物冠）（34×36：由两个植入物支撑的三单元固定桥，植入位置为34，36）。植入物的应力分布和VonMises应力值，在垂直和45°倾斜载荷下分析牙冠和植入物周围的骨骼。
结果：皮质骨中的应力主要集中在种植体颈部周围，四个模型的最大VonMises应力（MVMS）在垂直载荷下为11.6-16.1MPa，在45°倾斜载荷下为61.74-96.49MPa。松质骨中的应力集中在植入物基部周围，四个模型的MVMS在垂直载荷下为3.075-3.899MPa，在45°倾斜载荷下为5.021-6.165MPa。修复冠的应力主要集中在桥梁的连接件上，四个模型的MVMS在垂直载荷下为23.38-26.28MPa，在45°倾斜载荷下为53.14-56.35MPa。种植体界面的应力主要集中在桥附近较小的种植体表面,四个模型的MVMS在垂直载荷下为21.12-33.25MPa，在45°倾斜载荷下为83.73-138.7MPa。
结论：在垂直载荷和45°倾斜载荷下，四种模型的应力分布良好。结合部分牙冠的三单元固定桥的设计可能是设计下颌自由端无牙症患者治疗计划的可用选择。
