ELsyad Moustafa Abdou, El Ghany Kabil Ahmed Abd, El Mekawy Nesreen
1 Department of Removable Prosthodontic, Faculty of Dentistry, Mansoura University, Eldakahlia, Egypt.
2 Faculty of Dentistry, University of Mansoura, Eldakahlia, Egypt.
J Oral Implantol. 2017 Apr;43(2):100-106. doi: 10.1563/aaid-joi-D-16-00075. Epub 2017 Jan 3.
The aim of this in vitro study was to evaluate the effect of implant position and edentulous span length on stresses around implants assisting claspless distal extension partial overdentures. Four bilateral mandibular distal extension acrylic models were constructed. Two implants were inserted in the distal extension ridges parallel to each other and perpendicular to the ridges. Based on the implant position, models were categorized into two groups: Group I, mesial implants position and Group II, distal implant position. Each group was subdivided into 2 subgroups according to the length of edentulous span: Subgroup a, long span and Subgroup b, short span. Four claspless partial overdentures were fabricated on the models and retained to the implants with ball-and-socket attachments. Three strain gauges were cemented to the acrylic resin at buccal, lingual, and distal sides of each implant. Static unilateral vertical load of 60N was applied in the central fossae of the first molar, and peri-implant stresses were measured on loading and nonloading sides. Distal implant placements recorded significantly higher peri-implant stresses than did mesial implant placements. Long saddle recorded significantly higher stresses than did short saddle. The greatest peri-implant stresses were recorded with distal placement and long saddle at the loading side. At loading and nonloading sides, the mesial placement with a short saddle recorded the lowest strain. For mandibular distal extension partial overdentures, a mesially placed implant combined with short saddle may be preferable to a distally placed implant combined with long saddle, as the former was associated with reduced peri-implant stresses.
本体外研究的目的是评估种植体位置和无牙区跨度长度对辅助无卡环远中游离端覆盖义齿的种植体周围应力的影响。构建了四个双侧下颌远中游离端丙烯酸树脂模型。在远中游离端牙槽嵴上相互平行且垂直于牙槽嵴插入两颗种植体。根据种植体位置，模型分为两组：I组，种植体近中位置；II组，种植体远中位置。每组根据无牙区跨度长度再细分为两个亚组：a亚组，长跨度；b亚组，短跨度。在模型上制作四个无卡环覆盖义齿，并用球帽附着体与种植体相连。在每个种植体的颊侧、舌侧和远中侧的丙烯酸树脂上粘结三个应变片。在第一磨牙中央窝施加60N的静态单侧垂直载荷，并在加载侧和非加载侧测量种植体周围应力。远中种植体位置记录的种植体周围应力显著高于近中种植体位置。长跨度记录的应力显著高于短跨度。加载侧远中种植体位置和长跨度记录的种植体周围应力最大。在加载侧和非加载侧，近中种植体位置和短跨度记录的应变最低。对于下颌远中游离端覆盖义齿，近中种植体位置与短跨度相结合可能比远中种植体位置与长跨度相结合更可取，因为前者与种植体周围应力降低相关。
