Department of Prosthodontics, University of Berne, Berne, SwitzerlandDepartment of Oral Surgery, University of Witten/Herdecke, Witten, GermanyDepartment of Prosthetic Dentistry, Propaedeutics and Material Science, University of Bonn, Bonn, GermanyDepartment of Periodontology, Operative and Preventive Dentistry, University of Bonn, Bonn, Germany.
Clin Oral Implants Res. 2011 Oct;22(10):1185-1192. doi: 10.1111/j.1600-0501.2010.02090.x. Epub 2011 Feb 15.
The concept of platform switching has been introduced to implant dentistry based on observations of reduced peri-implant bone loss. However, randomized clinical trials are still lacking. This study aimed to test the hypothesis that platform switching has a positive impact on crestal bone-level changes.
Two implants with diameters of 4 mm were inserted epicrestally into one side of the posterior mandibles of 25 subjects. After 3 months of submerged healing, the reentry surgery was performed. On the randomly placed test implant, an abutment 3.3 mm in diameter was mounted, resulting in a horizontal circular step of 0.35 mm (platform switching). The control implant was straight, with an abutment 4 mm in diameter. Single-tooth crowns were cemented provisionally. All patients were monitored at short intervals over the course of 1 year. Standardized radiographs and microbiological samples from the implants' inner spaces were obtained at baseline (implant surgery), and after 3, 4, and 12 months.
After 1 year, the mean radiographic vertical bone loss at the test implants was 0.53±0.35 mm and at the control implants, it was 0.58±0.55 mm. The mean intraindividual difference was 0.05±0.56 mm, which is significantly <0.35 mm (P=0.0093, post hoc power 79.9%). The crestal bone-level changes depended on time (P<0.001), but not on platform switching (P=0.4). The implants' internal spaces were contaminated by bacteria, with no significant differences in the total counts between the test and the control at any time point (P=0.98).
The present randomized clinical trial could not confirm the hypothesis of a reduced peri-implant bone loss at implants restored according to the concept of platform switching.
基于观察到的种植体周围骨量减少，平台转换的概念已被引入种植体牙科。然而，仍缺乏随机临床试验。本研究旨在检验以下假设，即平台转换对种植体边缘骨水平变化有积极影响。
将 25 名受试者下颌后牙一侧的 2 个直径为 4 毫米的种植体牙骨顶植入。经过 3 个月的淹没愈合，进行再入手术。在随机放置的测试植入物上，安装直径为 3.3 毫米的基台，形成 0.35 毫米的水平圆形台阶（平台转换）。对照植入物为直型，直径为 4 毫米的基台。单冠临时粘固。所有患者在 1 年内进行短期监测。在基线（种植手术）、植入后 3、4 和 12 个月时，从种植体内部空间获得标准化的 X 光片和微生物样本。
1 年后，测试植入物的平均放射学垂直骨损失为 0.53±0.35 毫米，对照植入物为 0.58±0.55 毫米。个体内平均差异为 0.05±0.56 毫米，显著<0.35 毫米（P=0.0093，事后功率 79.9%）。边缘骨水平的变化取决于时间（P<0.001），但与平台转换无关（P=0.4）。种植体内部空间被细菌污染，在任何时间点，测试组和对照组的总计数均无显著差异（P=0.98）。
本随机临床试验不能证实根据平台转换概念修复的种植体周围骨量减少的假设。
