Department of Dental Sciences, University of Bologna, Bologna, Italy.
Int J Prosthodont. 2012 May-Jun;25(3):279-89.
The aim of this study was to prospectively evaluate clinical and radiographic outcomes of ultrashort implants (4-mm diameter, 6-mm length) supporting fixed partial dentures in severely atrophic posterior mandibles.
Twenty-five patients with posterior edentulous mandibular spans and 7- to 8-mm residual bone heights above the mandibular canal were enrolled. In total, 61 submerged implants were placed and loaded 5 to 6 months later. Patients were followed for 2 years after prosthesis connection with clinical, radiographic, and resonance frequency analysis (RFA) examinations.
Two implants failed in one patient before loading; all other implants showed favorable clinical and radiographic findings throughout the observation period (2-year survival and success rate: 96.8%). Postoperative pain and swelling were negligible. Mean changes in marginal bone levels were stable (0.40 ± 0.23, 0.51 ± 0.38, and 0.60 ± 0.13 mm after 6 months and 1 and 2 years, respectively) and were unaffected by measured crown-to-implant ratios (range: 1.31 to 3.12). Mean RFA values increased significantly from implant placement (67.35 ± 6.67) to 2 years (72.91 ± 5.07, P < .0001). Prosthetic complications included two prosthesis decementations, three ceramic veneer chippings, and one prosthesis screw loosening.
Within the limitations of the short follow-up period, the use of 6-mm-long implants was a predictable treatment method for patients with atrophic posterior mandibles and increased crown-to-implant ratios.
本研究旨在前瞻性评估超短种植体（直径 4mm，长 6mm）在严重萎缩的下颌后牙区支持固定局部义齿的临床和影像学效果。
共纳入 25 名下颌后牙区缺失且下颌管上方剩余骨高度为 7-8mm 的患者。共植入 61 枚植入物并于 5-6 个月后负载。在修复体连接后，患者接受了 2 年的随访，包括临床、影像学和共振频率分析（RFA）检查。
在负载前，1 名患者的 2 枚种植体失败；所有其他种植体在整个观察期（2 年生存率和成功率：96.8%）均表现出良好的临床和影像学表现。术后疼痛和肿胀轻微。边缘骨水平的平均变化稳定（负载后 6 个月、1 年和 2 年分别为 0.40 ± 0.23、0.51 ± 0.38 和 0.60 ± 0.13mm），且不受测量的冠根比（范围：1.31-3.12）的影响。RFA 值从植入时（67.35 ± 6.67）显著增加至 2 年时（72.91 ± 5.07，P<.0001）。修复体并发症包括 2 例修复体脱落、3 例陶瓷贴面崩瓷和 1 例修复体螺丝松动。
在随访时间较短的限制内，对于后牙区严重萎缩且冠根比增加的患者，使用 6mm 长的种植体是一种可预测的治疗方法。
