Clinic of Conservative and Preventive Dentistry, Center of Dental Medicine, Zurich, Switzerland.
Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, Zurich, Switzerland.
Clin Oral Implants Res. 2020 May;31(5):488-494. doi: 10.1111/clr.13584. Epub 2020 Feb 12.
To follow-up the radiographic changes in peri-implant bone of short (6 mm, test group) and long (10 mm, control group) single-unit implants five years after loading.
Forty-three implants of the test and 44 implants of the control group could be reassessed from 96 originally included implants. Standardized areas of interest (AOI) were defined in the peri-implant bone at pre-defined locations at mid-length on both sides of the implants, and at the apex. An arbitrary mean grey scale value (GSV) was calculated for the AOI after brightness calibration of the radiographs. Changes for GSV were calculated and tested for possible inter- and intra-group differences using the Mann-Whitney and Wilcoxon tests.
The calculated intra-group differences between baseline and 5 years in the test group accounted for 2.4 ± 19.6 (i.e. slight brightening) and -6.2 ± 20.2 for the control group (i.e. slight shading), which resulted in a statistically significant difference in GSV change (p < .05). Crown-to-implant ratio was the only parameter showing an effect on GSV change (p = .001).
Assessing conventional radiographs, longer implants showed a slightly stronger change of radiopacity of the peri-implant bone (slight loss of density) than short ones (slightly enhanced density) after five years of loading.
随访种植体负荷 5 年后短（6mm，试验组）和长（10mm，对照组）单颗种植体周围骨的影像学变化。
96 颗初始纳入种植体中，有 43 颗试验组和 44 颗对照组种植体可重新评估。在种植体两侧中间长度和根尖的预设位置，定义了标准化感兴趣区（AOI）。对 X 光片进行亮度校准后，计算 AOI 的任意平均灰度值（GSV）。使用 Mann-Whitney 和 Wilcoxon 检验测试组和对照组的 GSV 变化是否存在组间和组内差异。
试验组的组内差异在基线和 5 年时计算为 2.4±19.6（即轻度变亮），对照组为-6.2±20.2（即轻度变深），导致 GSV 变化存在统计学显著差异（p<0.05）。冠根比是唯一对 GSV 变化有影响的参数（p=0.001）。
评估常规 X 光片，负荷 5 年后，长种植体周围骨的放射性密度（密度略有丧失）变化略强于短种植体（密度略有增强）。
