Birdi Hardeep, Schulte John, Kovacs Alejandro, Weed Meghan, Chuang Sung-Kiang
University of Minnesota School of Dentistry, Minneapolis, MN, USA.
J Oral Implantol. 2010;36(6):425-33. doi: 10.1563/AAID-JOI-D-09-00071. Epub 2010 Jun 14.
Excessive crown-implant ratios have been cited in the literature as being detrimental to long-term implant survival. However, unfavorable crown-implant ratios have not yet been established. The primary aim of this study was to determine the crown-implant ratios of single-tooth implant-supported restorations on short-length implants in a clinical practice, and to evaluate the health of these implants via mesial and distal first bone-to-implant contact levels. Additionally, the relationship between crown-implant ratios and proximal first bone-to-implant contact levels will be evaluated. In this retrospective cohort study, the cohort was composed of 194 patients who possessed at least 1 single 5.7 mm or 6 mm length plateau design implant-supported restoration that had been surgically placed between February 1997 and December 2005. A chart review was performed to acquire the most recent radiographs in which both the entire crown and the implant were visible. The length of the crown and implant was measured directly from the radiographs using consistent magnification to calculate the crown-implant ratio. Mesial and distal first bone-to-implant contact levels were measured using 3 times magnification and were mathematically corrected for distortion. The last available radiograph was used to measure bone levels. Follow-up time was calculated from the day of implant placement to the date of the last available radiograph. Statistical analyses with analysis of variance mixed models were used. Data from 309 single implant-supported fixed restorations were tabulated and included in the study. The mean (SD) follow-up time was 20.9 (23.2) months, with a range of 15.6 to 122.8 months. The mean crown length (SD) was 13.4 (2.6) mm, with a range of 6.2 to 21.7 mm. The mean (SD) crown-implant ratio was 2.0 (0.4) and ranged from 0.9 to 3.2. The average mesial and distal first bone-to-implant contact levels (SD) measured from the radiographs were -0.2 (0.7) mm and -0.2 (0.9) mm, respectively. No statistically significant relationship was observed between increasing crown-implant ratios and decreasing mesial and distal first bone-to-implant contact levels around the implant with P values of .94 and .57, respectively. In this investigation, mesial and distal first bone-to-implant contact levels on short-length implants fall within the established guidelines for success. Also, there are no associations between crown-implant ratios and first bone-to-implant contact levels.
文献中提到，牙冠 - 种植体比例过高对种植体的长期存活不利。然而，目前尚未明确不利的牙冠 - 种植体比例范围。本研究的主要目的是确定临床实践中短种植体单牙种植支持修复体的牙冠 - 种植体比例，并通过近中及远中第一个骨 - 种植体接触水平评估这些种植体的健康状况。此外，还将评估牙冠 - 种植体比例与近中第一个骨 - 种植体接触水平之间的关系。在这项回顾性队列研究中，队列由194例患者组成，这些患者至少有1颗长度为5.7毫米或6毫米的单颗平台设计种植支持修复体，于1997年2月至2005年12月期间手术植入。通过查阅病历获取最新的X光片，片中需能清晰看到整个牙冠和种植体。使用一致的放大倍数直接从X光片中测量牙冠和种植体的长度，以计算牙冠 - 种植体比例。使用3倍放大倍数测量近中及远中第一个骨 - 种植体接触水平，并对图像失真进行数学校正。使用最后一张可用的X光片测量骨水平。随访时间从种植体植入日计算至最后一张可用X光片的日期。采用方差分析混合模型进行统计分析。对309个单种植体支持的固定修复体的数据进行列表并纳入研究。平均（标准差）随访时间为20.9（23.2）个月，范围为15.6至122.8个月。平均牙冠长度（标准差）为13.4（2.6）毫米，范围为6.2至21.7毫米。平均（标准差）牙冠 - 种植体比例为2.0（0.4），范围为0.9至3.2。从X光片中测量的平均近中及远中第一个骨 - 种植体接触水平（标准差）分别为 -0.2（0.7）毫米和 -0.2（0.9）毫米。牙冠 - 种植体比例增加与种植体周围近中及远中第一个骨 - 种植体接触水平降低之间未观察到统计学上的显著关系，P值分别为0.94和0.57。在本研究中，短种植体的近中及远中第一个骨 - 种植体接触水平符合已确立的成功标准。此外，牙冠 - 种植体比例与第一个骨 - 种植体接触水平之间没有关联。
