Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, NY, USA.
Clin Oral Implants Res. 2014 Feb;25(2):e22-9. doi: 10.1111/clr.12037. Epub 2012 Oct 1.
The purpose of this study was to assess the effect of inter-implant distance on interproximal bone utilizing platform switching. Analysis of interproximal bone usually depends on traditional two-dimensional radiographic assessment. Although there has been increased reliability of current techniques, there has been an inability to track bone level changes over time and in three dimensions. Micro-CT has provided three-dimensional imaging that can be used in conjunction with traditional two-dimensional radiographic techniques.
This study was performed on 24 female minipigs. Twelve animals received three implants with an inter-implant distance of 3 mm on one side of the mandible and another three implants on the contra-lateral side, where the implants were placed 2 mm apart creating a split mouth design. Twelve other animals received three implants with an inter-implant distance of 3 mm on one side of the mandible and another three implants on the contra-lateral side, where the implants were placed 4 mm apart creating a split mouth design too. The quantitative evaluation was performed comparatively on radiographs taken at t 0 (immediately after implantation) and at t 8 weeks (after termination). The samples were scanned by micro-computed tomography (μCT) to quantify the first bone to implant contact (fBIC) and bone volume/total volume (BV/TV). Mixed model regressions using the nonparametric Brunner-Langer method were used to determine the effect of inter-implant distance on the measured outcomes.
The change in bone level was determined using radiography and its mean was 0.05 mm for an inter-implant distance of 3 and 0.00 mm for a 2 mm distance (P = 0.7268). The mean of this outcome was 0.18 mm for the 3 mm and for 4 mm inter-implant distance (P = 0.9500). Micro-computed tomography showed that the fBIC was always located above the reference, 0.27 and 0.20 mm for the comparison of 2-3 mm (P = 0.4622) and 0.49 and 0.34 mm for the inter-implant distance of 3 and 4 mm (P = 0.1699). BV/TV inside the defined parallelepipedic masks reached 82.38% for the 2 mm inter-implant distance and 85.00% for 3 mm, P = 0.8432. For the comparison of the 3-4 mm inter-implant distance, the means were 84.69% and 84.38%, respectively, P = 0.8401. Non-inferiority tests for the smaller inter-implant distances for both comparisons showed similar differences and similar tolerance ranges.
The effect of a smaller interproximal distances between implants on bone level, fBIC and BV/TV assessed by two convergent investigation methods, radiology and μCT, was similar to that of larger distances. Implants can potentially be placed 2 mm apart instead of 3 mm and 3 mm apart instead of 4 mm when platform switching is utilized. Further research with a conventional platform is warranted.
本研究旨在评估使用平台转换技术时种植体之间的距离对近中骨的影响。对近中骨的分析通常依赖于传统的二维放射评估。尽管目前的技术具有更高的可靠性，但仍然无法跟踪随时间和三维空间的骨水平变化。微计算机断层扫描（micro-CT）提供了可与传统二维放射技术结合使用的三维成像。
本研究在 24 只雌性小型猪中进行。12 只动物在一侧下颌骨上植入三个种植体，种植体之间的距离为 3mm，在对侧下颌骨上植入另外三个种植体，种植体之间的距离为 2mm，形成分裂口设计。另外 12 只动物在一侧下颌骨上植入三个种植体，种植体之间的距离为 3mm，在对侧下颌骨上植入另外三个种植体，种植体之间的距离为 4mm，也形成分裂口设计。在 t0（植入后立即）和 t8 周（终止时）拍摄的放射影像上进行定量评估。使用微计算机断层扫描（micro-CT）对样本进行扫描，以定量测量第一骨与种植体接触（fBIC）和骨体积/总体积（BV/TV）。使用非参数 Brunner-Langer 方法的混合模型回归来确定种植体之间的距离对测量结果的影响。
使用放射学确定骨水平的变化，种植体之间的距离为 3mm 时平均为 0.05mm，距离为 2mm 时平均为 0.00mm（P=0.7268）。种植体之间的距离为 3mm 和 4mm 时，该结果的平均值分别为 0.18mm（P=0.9500）。微计算机断层扫描显示，fBIC 始终位于参考值上方，2mm-3mm 比较时为 0.27mm 和 0.20mm（P=0.4622），3mm-4mm 比较时为 0.49mm 和 0.34mm（P=0.1699）。在定义的平行六面体掩模内的 BV/TV 达到 2mm 种植体之间的距离为 82.38%，3mm 时为 85.00%，P=0.8432。3mm-4mm 种植体之间的距离比较时，平均值分别为 84.69%和 84.38%，P=0.8401。对于两种比较的较小种植体之间距离的非劣效性检验显示出相似的差异和相似的容差范围。
使用两种收敛性调查方法（放射学和 micro-CT）评估种植体之间较小的近中距离对骨水平、fBIC 和 BV/TV 的影响与较大距离相似。当使用平台转换技术时，种植体之间可以潜在地放置 2mm 而不是 3mm，放置 3mm 而不是 4mm。需要进一步进行使用传统平台的研究。
