Baron Monika, Haas Robert, Baron Werner, Mailath-Pokorny Georg
Department of Oral Surgery, Dental School, University of Vienna, Austria.
Int J Prosthodont. 2005 Sep-Oct;18(5):427-33.
In a retrospective study, the radiographs of 39 patients with Applegate-Kennedy Class I or II in the posterior mandible who had been treated with screw-anchored fixed partial dentures supported by IMZ implants and natural teeth were examined for the presence of radiologically detectable peri-implant bone loss. Furthermore, the results were correlated with a mathematical model.
The radiographs of the implants were digitized, and the areas of bone atrophy mesial and distal to the implants were determined semi-automatically. The data obtained were correlated with the distance between the implant and the abutment tooth. The connection between the tooth-supported crown and the implant-supported denture was made with a vertical screw-lock precision attachment. In a mathematical analysis it was assumed that the fixed partial prosthesis was a rigid beam with 3 elastically embedded supports.
The mean distance between the tooth and the first implant was 11.02 mm (SD: 4.24), and between the tooth and the second implant was 20.25 mm (SD: 5.16). Peri-implant bone loss significantly followed a rational function (mesial implant: P = .03, distal implant: P = .02), meaning that, as the tooth-implant distance increased, the area of atrophy became rapidly larger and then diminished gradually. Distances of 8 to 14 mm between the tooth and the first implant and of 17 to 21 mm between the tooth and the second implant were associated with a more pronounced bone loss. These results were also confirmed mathematically.
A tooth-implant distance of 8 to 14 mm for the first implant and 17 to 21 mm for the second implant should be avoided for implant placement if prosthetic rehabilitation is planned using a fixed partial denture supported by a premolar and 2 IMZ implants in the mandible. Although this investigation was done on IMZ implants only, the results were confirmed by a mathematical model, which indicated that the observed bone loss may be the same in other types of implants placed in the same positions.
在一项回顾性研究中，对39例下颌后部采用IMZ种植体和天然牙支持的螺丝固位固定局部义齿治疗的阿普尔盖特-肯尼迪I类或II类患者的X线片进行检查，以确定是否存在放射学上可检测到的种植体周围骨丢失。此外，将结果与一个数学模型进行关联分析。
将种植体的X线片数字化，半自动确定种植体近中和远中骨萎缩区域。将获得的数据与种植体和基牙之间的距离进行关联分析。牙支持冠与种植体支持义齿之间的连接采用垂直螺丝锁精密附着体。在数学分析中，假定固定局部义齿是一个具有3个弹性嵌入支撑的刚性梁。
牙齿与第一颗种植体之间的平均距离为11.02mm（标准差：4.24），与第二颗种植体之间的平均距离为20.25mm（标准差：5.16）。种植体周围骨丢失明显呈有理函数关系（近中种植体：P = 0.03，远中种植体：P = 0.02），这意味着，随着牙-种植体距离增加，萎缩面积迅速增大，然后逐渐减小。牙齿与第一颗种植体之间距离为8至14mm以及与第二颗种植体之间距离为17至21mm时，骨丢失更为明显。这些结果在数学上也得到了证实。
如果计划使用下颌前磨牙和2颗IMZ种植体支持的固定局部义齿进行修复，种植体植入时应避免第一颗种植体的牙-种植体距离为8至14mm，第二颗种植体为17至21mm。尽管本研究仅针对IMZ种植体进行，但数学模型证实了结果，表明在相同位置植入的其他类型种植体中观察到的骨丢失情况可能相同。
