Tom Kobe^1,*; Aleš Fidler^2,3; Marko Kuralt²; Rok Gašperšič^1,4

¹Department of Oral Medicine and Periodontology; ²Department of Restorative Dentistry and Endodontics, University Medical Centre Ljubljana; ³Department of Endodontics and Operative Dentistry; ⁴Department of Oral Medicine and Periodontology, Faculty of Medicine, Ljubljana, Slovenia

Background: 3D position of the implant became more predictable with static computer-aided implant surgery. However, the errors are accumulating during surgical template fabrication and implant surgery, resulting in a considerable deviation between the implant's virtually planned and actual position. Offset is widely used in a surgical guide design, to allow placement on remaining teeth. However, it also enables micro-movements during guided implant placement, thus representing a potential source of error.

Aim/Hypothesis: The present study aims to assess the stability of a novel tooth-supported implant surgical guide design – snap-FIT guide (SF) in a pre-clinical setup (Figure 1). It is inspired by the removable dentures clasp principle, with strategically placed retention surfaces.

Material and Methods: Four patients with a single missing tooth underwent CBCT and intra-oral optical scan. Scans were superimposed and implants virtually placed in implant planning software (BlueSkyBio, USA). Two implant surgical guides for each clinical situation were designed: classical guide (CG) with the default software settings: offset 0.2 mm, guide thickness 3 mm, and no undercuts, and a novel SF. 3D printing and post-processing of templates were done by the manufacturer instructions (Formlabs, USA). Dental models and surgical guides were positioned on the custom 3D printed testing stand and the metal handle (Straumann, CH) inserted into the guide (Figure 2). Surgical guide displacement during surgery was simulated by applying pressing or pulling force of 0.1 and 5N on the metal handle with a digital force gauge. After each force application, the guide position was captured with an intraoral scanner. Scans were imported into analysis software (GOM Inspect, Germany) and implants virtually placed.

Results: Source files of dental models and surgical guides were superimposed to the scanned data, using local best-fit, with an alignment error of 0.12 ± 0.03 mm in CG and 0.11 ± 0.03 mm in the SF group (p = 0.37) (Figure 3). Both surgical guides fitted well on the dental model, with a vertical discrepancy of 0.76 ± 0.49 mm (CG) and 0.60 ± 0.4 mm (SF); p = 0.41. With an applied force of 0.1N, SF guide significantly better resisted vertical displacement than CG (0.68 ± 0.54 mm vs 1.49 ± 1.69 mm, p < 0.05). Implant placement error at the entry point was 0.76 ± 0.43 mm vs 1.79 ± 1.15 mm (p < 0.05), at the apex 1.13 ± 0.59 mm vs 3.37 ± 2.32 mm (p < 0.05) and the angle deviation of 3.11 ± 2.05° vs 10.79 ± 8.38° (p < 0.05) for SF and CG, respectively. With an applied force of 5N, all CG dislodged from the dental model, precluding the displacement measurements. Vertical displacement of SF guide was 1.44 ± 1.29 mm, with projected implant placement error of 1.59 ± 0.75 mm at the entry point, 2.62 ± 1.42 mm at apex, and 7.33 ± 4.69° angle deviation.

Conclusion and Clinical implications: The novel SF surgical guide design demonstrates a potential for a considerable increase of implant placement accuracy. At a clinically important level, a 2-3 fold decrease in implant deviation parameters were found. The proposed approach is achievable with a simple modification of surgical guide design, without requiring additional materials, devices or procedures. Clinical trials are needed to verify the results of present study and assess SF's clinical feasibility in implant dentistry.

Disclosure of Interest: None Declared

Keywords: accuracy, dental implants, guided implant surgery

汤姆科比^1,* ; 阿莱什·菲德勒^2,3 ; 马尔科·库拉特² ; Rok Gašperšič ^1,4

¹口腔医学与牙周病学系；²卢布尔雅那大学医学中心修复牙科和牙髓病学系；³牙髓病学和牙科手术科；⁴斯洛文尼亚卢布尔雅那医学院口腔医学和牙周病学系

背景：通过静态计算机辅助植入手术，植入物的 3D 位置变得更加可预测。然而，在手术模板制造和植入手术过程中误差会不断累积，导致植入物的虚拟计划位置与实际位置之间存在相当大的偏差。偏置广泛用于手术导板设计，以允许放置在剩余牙齿上。然而，它也会在引导种植体植入过程中实现微动，因此代表了潜在的错误来源。

目的/假设：本研究旨在评估一种新型牙齿支撑种植体手术导板设计——咬合式导板 (SF) 在临床前设置中的稳定性（图 1）。它的灵感来自可拆卸假牙扣原理，具有战略性放置的保持表面。

材料与方法：四名缺牙的患者接受了 CBCT 和口腔内光学扫描。扫描叠加，种植体虚拟放置在种植体规划软件（BlueSkyBio，美国）中。针对每种临床情况设计了两种种植体手术导板：经典导板 (CG)，默认软件设置：偏移 0.2 毫米，导板厚度 3 毫米，无咬边，以及新型 SF。模板的 3D 打印和后处理由制造商说明（Formlabs，美国）完成。牙科模型和手术导板放置在定制的 3D 打印测试台上，金属手柄 (Straumann, CH) 插入导板（图 2）。通过使用数字测力计在金属手柄上施加 0.1 和 5N 的压力或拉力来模拟手术过程中的手术导板位移。每次施力后，引导位置是用口腔内扫描仪捕获的。将扫描结果导入分析软件（GOM Inspect，德国）并虚拟放置植入物。

结果：牙科模型和手术导板的源文件被叠加到扫描数据上，使用局部最佳拟合，CG 对齐误差为 0.12 ± 0.03 mm，SF 组对齐误差为 0.11 ± 0.03 mm（p = 0.37）（图3）。两个手术导板都非常适合牙科模型，垂直偏差为 0.76 ± 0.49 mm (CG) 和 0.60 ± 0.4 mm (SF)；p = 0.41。施加 0.1N 的力时，SF 导轨明显比 CG 更好地抵抗垂直位移（0.68 ± 0.54 mm 与 1.49 ± 1.69 mm，p < 0.05）。入口点的种植体放置误差为 0.76 ± 0.43 mm 与 1.79 ± 1.15 mm ( p < 0.05)，顶点为 1.13 ± 0.59 mm 与 3.37 ± 2.32 mm ( p< 0.05) 和 3.11 ± 2.05° 与 10.79 ± 8.38° ( p < 0.05) 的 SF 和 CG的角度偏差，分别。在施加 5N 的力时，所有 CG 从牙科模型上脱落，排除了位移测量。SF 导向器的垂直位移为 1.44 ± 1.29 mm，植入点的预计种植体放置误差为 1.59 ± 0.75 mm，顶点为 2.62 ± 1.42 mm，角度偏差为 7.33 ± 4.69°。

结论和临床意义：新型 SF 手术导板设计显示出显着提高种植体放置精度的潜力。在临床上重要的水平上，发现种植体偏差参数降低了 2-3 倍。所提出的方法可以通过对手术导板设计的简单修改来实现，而不需要额外的材料、设备或程序。需要临床试验来验证本研究的结果并评估 SF 在种植牙学中的临床可行性。

利益披露：无申报

关键词: 准确性, 种植牙, 引导种植手术