Department of Oral and Maxillofacial Surgery, University Medical Center, Freiburg, Germany.
Department of Restorative Dentistry Hamdan bin Mohammed College of Dental Medicine Mohammed bin Rashid University for Health and Medical Sciences, Dubai, UAE.
J Prosthodont. 2017 Jan;26(1):34-41. doi: 10.1111/jopr.12362. Epub 2015 Oct 14.
Optical transfer is realized with system-specific transfer posts (scan bodies) mounted on dental implants or on implant analogs. This study presents a novel algorithm for creation of geometry on the surface of dental implant scan bodies and examines the precision of the optical acquisition of scan bodies and the precision of the position of the screw-tightened scan bodies on dental implant analogs.
Scan bodies of two different implant manufacturers (S1, S2), one with a horizontal and two with different conical implant-abutment geometries were screw tightened to implant analogs in stone casts with a 10 Ncm torque. The stone casts were scanned ten times with a dental lab scanner. Each scan body was removed and positioned ten times; after each repositioning, a scan was performed. The cylinder axis of every scan body and the occlusal horizontal scan body surface was virtually reconstructed. At the intersection of the cylinder axis and the horizontal plane a point was marked. The mean deviation of this point in consecutive scans and the angle between the scan body axes in the virtual models were measured, and the standard deviation was calculated. Statistical significance of the results was tested with a Kruskal-Wallis Test and Mann-Whitney U-test for pairwise comparison (p < 0.05).
The mean deviation of the angle between two scan bodies was 0.05° (SD 0.04°) (S1) and 0.14° (SD 0.08°) (S2). After detachment and repositioning of the scan bodies the mean deviation was 0.05° (SD 0.03°) (S1) and 0.16° (SD 0.08°) (S2). The mean deviation of the central point was 5.7 μm (SD 3.4 μm) without detachment and 4.9 μm (SD 2.6 μm) after detachment and repositioning (S1). For system S2 the mean deviation of the central point was 13.4 μm (SD 7.2 μm) after repeated scanning and 15 μm (SD 5 μm) after detachment, repositioning, and repeated scanning.
The precision of extraoral scanning of scan bodies is dependent on the scan body surface design and geometry. The precision of scanning with an extraoral model scanner differed between the scan body geometries and inter-scan body distances. The precision of dental implant scan body scanning was not significantly influenced by detachment and repositioning of the scan body.
光学传递是通过安装在牙科种植体或种植体模拟体上的特定系统传输柱（扫描体）来实现的。本研究提出了一种在牙科种植体扫描体表面创建几何形状的新算法，并检验了扫描体的光学采集精度和螺丝拧紧的扫描体在种植体模拟体上的位置精度。
将两种不同种植体制造商（S1、S2）的扫描体分别拧紧到带有 10 Ncm 扭矩的石铸模型中的种植体模拟体上。将石铸模型用牙科实验室扫描仪扫描 10 次。每次扫描后都将扫描体取下并重新定位 10 次，然后再次进行扫描。每个扫描体的圆柱轴和咬合水平扫描体表面都被虚拟重建。在圆柱轴和水平平面的交点处标记一个点。测量连续扫描中该点的平均偏差和虚拟模型中扫描体轴之间的角度，并计算标准差。用 Kruskal-Wallis 检验和 Mann-Whitney U 检验（p<0.05）对结果进行统计学显著性检验。
两个扫描体之间的角度的平均偏差为 0.05°（SD 0.04°）（S1）和 0.14°（SD 0.08°）（S2）。扫描体分离和重新定位后，平均偏差为 0.05°（SD 0.03°）（S1）和 0.16°（SD 0.08°）（S2）。未分离时中心点的平均偏差为 5.7μm（SD 3.4μm），分离和重新定位后为 4.9μm（SD 2.6μm）（S1）。对于系统 S2，重复扫描后中心点的平均偏差为 13.4μm（SD 7.2μm），分离、重新定位和重复扫描后为 15μm（SD 5μm）。
扫描体的口腔外扫描精度取决于扫描体表面设计和几何形状。不同扫描体几何形状和扫描体之间的距离对外置模型扫描仪的扫描精度有影响。扫描体的分离和重新定位对牙科种植体扫描体的扫描精度没有显著影响。
